The Technical Feasibility of Zero Net Energy Buildings in California. DRAFT Report. Pacific Gas & Electric Company

Transcription

1 On behalf of Southern California Edison San Diego Gas and Electric Company Southern California Gas Company The Technical Feasibility of Zero Net Energy Buildings in California ZNE/ Draft 2 November 20, 2012 Job number Arup North America Ltd 560 Mission Street Suite 700 San Francisco United States of America

2 Document Verification 1 Document title Job number File reference Document ref ZNE/ This is a draft report, with the research underlying the report continuing through the end of With work continuing, the research team did not presently have time to incorporate all elements of the project into this report. Key components of the inputs and outputs are reported here, and details will continue to be expanded in successive drafts through the end of the year. Your feedback on the methodology, design decisions, and reporting metrics will be greatly appreciated. Contents 1 Executive Summary The Value of Universal Applicability A Note on Density 6 2 Purpose The Feasibility of ZNE ZNE Design Strategies Barriers and Opportunities ZNE Scenario Analysis Tool 8 Page ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 1

3 3 Background Coordination Efforts Metrics Representative Buildings Representative Climate Zones Reference Year 14 4 Methodology Efficiency First, Then Renewables Renewable Energy and Combined Heat & Power Key Research Inputs and Assumptions 21 5 Exemplar Prototypes Single Family Residential Multi-Family Low-Rise Medium Office Large Office Secondary School Hospital Warehouse Multifamily Highrise Grocery Strip Mall Lodging Restaurant 62 6 Costs 63 7 ZNE Scenario Analysis Tool Scenario Analysis Tool Methodology 64 8 Impediments and Opportunities LEDs Turning Off Unused Equipment Plug Loads Little Net Reduction in Heating Minimize Systems Working at Cross-Purposes Natural Ventilation Residential Ducts in Conditioned Space Vertical Transportation Photovoltaics 73 ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 2

4 8.10 Federal Preemption 74 9 Reference List 75 ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 3

5 1 Executive Summary California s Zero Net Energy new construction goals (ZNE goals) set forth in the California Long Term Energy Efficiency Strategic Plan (the Strategic Plan) appear to be technically feasible for a large portion of the building stock. There are a few challenging building types, and the dependency of ZNE on solar energy will make some locations challenging. But overall, this research suggests that a wide portion of California s new construction can move to Zero Net Energy by 2020 for homes and 2030 for commercial buildings using energy efficiency measures that are more than likely to be available at that time. This table is a summary of projected 2020 best in class performance data for two climate zones: TDV$/ft 2 (30 yr) Percent of 2020 New Build 15: Palm Springs 12: Sacramento 16: (Sierras) Load: Solar: Net: Load: Solar: Net: Load: Solar: Net: Single Family Home 52% Multifamily Lowrise* 5% Multifamily Highrise* 3% Medium Office 2% Large Office 7% w/ parking PV Strip Mall 7% School (in process) 3% Large Hotel 2% Grocery 2% Sit-down Restaurant 1% Hospital 2% w/ parking PV Warehouse 6% College 2% Other 8% *From Title construction volume forecasts. Current California residential construction is close to 50% multifamily. The term ZNE, when used in this report, defines a building that has high performance energy efficiency features from envelope to mechanical systems to plug load equipment with sufficient photovoltaics installed to offset the remaining load using either a Site-kBtu or TDV metric. While the metric used can affect the amount of PV that needs to be installed, the precise metric often will not affect the ability of a building to reach ZNE. ZNE, in the context of this report, is an energy model based definition. It is not an operational definition. ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 4

6 While this research suggests that ZNE goals should be largely achievable, that does not mean that it will be easy. It remains an aggressive target, requiring vigilance in almost all aspects of equipment engineering, building design, and construction. ZNE design efforts can require the integration of a myriad of optimized subcomponents, all making a small contribution to the overall improvement in building energy use. That said, there are a few design details that stand out in this research as being major contributors to pursuing the ZNE goals: Load Reductions: LED lighting performance moving rapidly forward, to over 200 lumens/watt by Sensor controlled equipment that minimizes just in case usage. Heating of cooled air, and cooling of heated air, needs to be further minimized. Minimizing plug loads will be critical to meeting the ZNE goals. Passive Systems: Much of California has an excellent climate for natural ventilation. Its use should be further encouraged. Active Systems: Move residential ducts out of the unconditioned attic. Hydronic systems will improve the performance of many buildings. Heat recovery, whether from exhaust air or mechanical equipment, can offset a significant portion of heating loads in some buildings. Renewable Energy: The challenge of ZNE is often one of available space for photovoltaics; increasing PV panel efficiency, thereby increasing power density, will help to address this challenge. Bringing parking lot PV installations into the ZNE equation can greatly increase a building s ability to offset remaining load once it has reached its energy efficiency target. 1.1 The Value of Universal Applicability Technologies and design strategies that can be applied both easily and across a high percentage of the built environment will show some of the greatest gains in moving the state toward the ZNE goals. These universal improvements include LED lighting efficiency, equipment integrated auto-off functions, PV panel efficiency improvements (offsetting all loads), and PV panel optimizers (also offsetting all loads). Transformers, whether a part of a commercial building or sitting on the grid to supply smaller buildings, represent another universal point of improvement. Transformers are especially worthy of design optimization in a ZNE context as ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 5

7 high-performance transformers perform notably better when operating at low loads. 1.2 A Note on Density Although not a direct topic of exploration in this research, density plays an important role in both overall energy use generally decreasing per capita energy use and the ability of a building to reach ZNE. This creates an inherent tension. More people in an office requires less lighting per capita. More people in an office results in less envelope gains per capita. However, those higher occupant densities also increase energy use per square foot, which is the standard metric for assessing building performance. Assessed more broadly, dense urban environments have much lower vehicular energy use per capita. At the same time, an on-site ZNE definition is heavily dependent on photovoltaics. Photovoltaics thrive on space. They offset the greatest amount of load when paired with low density occupancies and low density planning. Consistent with the State s loading order, it is probably preferable to foster higher density development that minimizes overall energy use, even at the cost of minimizing ZNE potential. Further policies will need to be developed to facilitate this balancing of objectives between building scale ZNE objectives and the State s broader carbon reduction goals. ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 6

8 2 Purpose The study will provide guidance to California s IOUs and the State in a number of contexts: 2.1 The Feasibility of ZNE This study is a preliminary stress test of the Strategic Plan s Zero Net Energy new construction objectives for 2020 and 2030 on a building-by-building basis. Most of the building types explored pass that test; when looked at in the context of construction volume, the weighted average of buildings that can likely be ZNE is even greater. Most single family residences and lowrise multifamily residences can likely be designed to meet the ZNE goals, and they alone comprise 50% of construction volume on a square foot basis. This is a technical feasibility study, and as such, evaluates what could be considered best-in-class performance. Design decisions were not constrained by cost, although overall constructability was a notable driver in implementing energy efficiency and renewable energy features in the prototypes. Essentially every building component embedded in these models has been specified on building projects in California by the engineering teams leading this research. A continuing goal of California s Investor Owned utilities and the State of California is to move best-in-class building design strategies into the mainstream to achieve the State s long-term energy efficiency goals. 2.2 ZNE Design Strategies A secondary purpose of the research is identifying the specific design strategies and technologies most likely to enable Zero Net Energy buildings in California in the coming decades. Those design strategies are implemented through a series of 12 typical prototypes selected to represent a broad selection of California s building stock. These prototypes, with optimized efficiency and renewable energy features, are known as exemplar prototypes within this research. The report details the design strategies as a series of improvements to the relevant energy models. The process is explained more in the Methodology chapter and Exemplar Prototypes chapter. As the research is ongoing, we are only reporting on seven of the prototypes in this draft. It is also likely that the design details of those prototypes will continue to be improved through the end of the research as strategies and technologies continue to be explored. In identifying design strategies that explore the boundaries of technical feasibility, this research is not necessarily intended to be a design guide for all of the building types explored. It illuminates one possible approach to reach the lowest possible energy use in a building, and its outputs are necessarily constrained by the nature of this prototype driven research. ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 7

9 The research focused on optimizing energy performance, not on optimizing overall cost effectiveness. Costs of the recommended measures will still be reported. 2.3 Barriers and Opportunities Along with the identification of ZNE enabling design strategies, this research also identifies some of the more important technical barriers or challenges in quickly advancing standard construction practices to pursue the ZNE goals. Complimenting that list, a series of notable opportunities are also presented (See Chapter 8). 2.4 ZNE Scenario Analysis Tool A companion output of this research is a Scenario Analysis Tool that will allow the IOUs to explore alternative design and performance combinations than those outlined in our exemplar prototypes. The tool will give an estimate of the relative change in energy performance across a number of metrics, looking at the interactive effects of the building subcomponents. This tool has been alternately described as the what if database, providing technical feasibility answers if, for instance, plug loads increase in volume rather than decrease, or if LED performance only moves to 180 lumens/watt rather than the projected 220 lumens/watt (See Chapter 7). ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 8

10 3 Background This section outlines some of the fundamental parameters of the research, with the Methodology chapter going into greater depth on the design process. The research looks strictly at on-site solutions to achieving Zero Net Energy on a building-bybuilding basis. 3.1 Coordination Efforts This Technical Feasibility Study, along with its parallel study the Road to ZNE, was conducted under the direction of the California Investor Owned Utilities (IOUs) and the California Public Utilities Commission (CPUC). Arup and the Heschong Mahone Group (HMG), the primary team leads on the Technical Feasibility Study and Road to ZNE Study, respectively, collaborated throughout on the key assumptions and focus areas of these corresponding research efforts. A Project Advisory Group (PAG) comprised of industry stakeholders provided insights to both project teams. 3.2 Metrics This research used two primary metrics for assessing the performance of buildings: EUI Metric: Site-kBtu TDV$ Attributes: Units: kbtu/ft 2 /yr This is a site metric and the metric by which the performance many ZNE buildings have historically been evaluated. Units: Dollars, based on 30-Year Net Present Value of Energy Time Dependent Valuation It is a hybrid between the societal valuation of energy costs and a participant valuation of energy costs. It can generally be considered a source metric The subcomponents of this metric are discussed in further detail below Site-kBtu (kbtu/ft 2 /yr) Site-kBtu is the most commonly used metric for ZNE discussions. It does not, however, value the time-of-use element of energy use or take into account the source-to-site energy conversion factors TDV (Time Dependent Valuation) TDV is a far more robust metric, accounting for source energy values, demand reduction values, the emitted carbon in energy production (valued at projected market prices), and a host of other variables. It is an elegant way to optimize building performance across a number of overlapping state objectives using a single metric. ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 9

11 This research has optimized buildings to minimize TDV$ on the energy efficiency side of the ZNE equation An Economic Metric TDV is, ultimately, an economic metric, aggregating costs for fuel, turbines, transmission systems, carbon, etc. Although the metric is sometimes reported as TDV kbtu, this is a policy implementation anomaly rather than TDV s native units. TDV$ is used, where necessary, to designate that it is the fiscal valuation being reported. This study uses exclusively the 30 year values for TDV. These values represent the net present value of energy use for the modeled building over a 30 year period. The 30 year net present values are derived from one year of energy modeling (8760 hours), but they do not represent per year values. The single year of energy modeling is used to extrapolate to 30 years of energy use. Interestingly, the 30 year TDV$ values for building performance are surprisingly close in absolute value terms to the corresponding kbtu/ft 2 /yr values. Buildings with higher levels of on-peak electricity use tend to have a higher TDV$ value as compared to Site-kBtu, whereas buildings with more off-peak usage will tend to have higher kbtu/ft 2 /yr values. This correlation mostly a convenient coincidence means that 30 year TDV$ values can generally be viewed in the same Great / Good / Not quite there lens that design and policy professionals are currently using to evaluate building performance based on a Site-kBtu metric. A few matched sets, by way of example: Metric: Bldg 1 Bldg 2 Bldg 3 Bldg 4 Bldg 5 Bldg 6 Avg. Site-kBtu TDV$ $11.9 $18.9 $66.7 $21.1 $10.3 $40.2 $28.2 One note of caution: the TDV$ values will change over time, with inflation and with evolving projections on the future cost of energy. At least for now, however, the two metrics are closely aligned in terms of their respective scales TDV as a Renewable Energy Metric Because TDV was developed to assess the value of energy efficiency measures, it is not yet clear that it is the best metric, without further modification, to value photovoltaic exports back onto the grid. Consumption and production values are reported in both Site-kBtu and TDV to provide some clarity on the policy implications of using those respective metrics. It is possible that a third, more appropriate metric will emerge for balancing energy consumption with energy exports back to the grid. ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 10

12 3.2.3 The Impact of Metric Choice As can be seen in the Change Logs associated with the Exemplar Prototypes, at least 90% of the time Site-kBtu tracks TDV$ in the level of comparable improvement for an efficiency measure. The few exceptions relate to measures that reduce cooling loads while simultaneously increasing some heating loads, such as window overhangs. More often than not, either metric will point towards the same optimal design decisions. The most notable difference in the metrics is in scaling a building s photovoltaic production to get to ZNE. PV production gets more credit in comparison to a building s energy consumption using the TDV$ metric as compared to a Site-kBtu metric. For buildings that are more consistently off-peak, such as homes, the choice of metric can have a big impact on the amount of PV required. For buildings where loads track more closely to PV production curves such as office buildings using either metric to specify a Zero Net Energy PV system would result in essentially the same size of PV system Time of Use kwh and Therm Energy Consumption The study also documents binned kwh and therm energy use data by summer and winter as well as on-peak and off-peak time periods for analysis from the perspective of utility customers. It is provided in the report for a few representative buildings, such as single family residence and medium office Weather All modeling was conducted using the Title weather files (Huang, 2010). These files make a notable improvement on earlier weather files by correlating the weather that drives building energy use with the weather driving the performance of the overall utility grid. This correlated modeling of both buildings and the utility grid allows for a proper accounting of the monetary impact of energy use during peak summer days. This correlation is further implemented through the Title TDV schedules. The average temperature within the Title weather files is 1 degree warmer than earlier Title 24 weather files Demand Peak demand is generally reported using the 250 Hour Method that calculates the weighted average peak for energy consumption across the 250 hours of the year with the highest overall demand on the grid. This schedule of hours is the same as that used to assign capacity values to the TDV schedules. Because many ZNE buildings can actually be net exporters during those peak events, their Demand valuation is actually negative. The buildings would certainly have a net positive demand at other times, on cloudy days or at night, but those ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 11

13 net positive demand days would not align with the peak grid hours. As such, the 250 hour demand values should not be used for estimating demand charges. Peak solar exports are reported as the single highest hourly value Carbon A driver of the State s ZNE strategies is the reduction of carbon emissions as directed by AB32. Carbon emissions are reported for the exemplar prototypes once PV offsets are applied to the estimated energy consumption. The following values were applied: Electricity Natural Gas MWh 0.30 tonnes Therm tonnes A building that is ZNE using a TDV metric will generally produce more carbon than a building that is ZNE using a site kbtu metric. This difference is more notable for residential buildings than for commercial buildings. The differences are tied to the relative sizes of installed PV systems (kw of capacity) necessary to move a building to ZNE under the different metrics. Notably, although electricity produces about 50% more carbon per site kbtu of energy use than does natural gas, in the situations where the energy sources are fungible such as space and water heating the much higher efficiency of heat pumps (COP = 3.0 = 300%) as compared to even condensing combustion technology (max = 97%) means that electrically driven heating can have a lower carbon footprint than natural gas heating. This somewhat surprising result derives from California s electric supply having a comparatively low carbon/kwh content. This analysis does not mean that heating with electricity will be less expensive in California, only that such heating might result in lower carbon emissions. ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 12

14 3.3 Representative Buildings This research uses 12 prototypes from 3 sources: Building Type: Source: Single Family Residence CEC Prototype adapted for use in EnergyPlus Multifamily Lowrise New model based on common multifamily projects Multifamily Highrise DOE EnergyPlus research prototype ASHRAE Medium Office DOE EnergyPlus research prototype ASHRAE Large Office DOE EnergyPlus research prototype ASHRAE Strip Mall DOE EnergyPlus research prototype ASHRAE Secondary School DOE EnergyPlus research prototype ASHRAE Large Hotel DOE EnergyPlus research prototype ASHRAE Grocery DOE EnergyPlus research prototype ASHRAE Sit-down Restaurant DOE EnergyPlus research prototype ASHRAE Hospital DOE EnergyPlus research prototype ASHRAE Warehouse DOE EnergyPlus research prototype ASHRAE College Energy use estimated via composite of related buildings The DOE research prototypes were chosen as the basis for the commercial research for a number of reasons: Uniformity with other building performance research projects. A high level of energy efficiency as a starting point when structured to meet ASHRAE The models are EnergyPlus files, and EnergyPlus is required to model many of the ZNE design strategies explored in this research. Integrated operational assumptions that are derived from CBECS, covering everything from lighting schedules, to equipment power densities, to occupant entry and exit driven infiltration rates. This standard operational data derived from CBECS is critical to establish normal patterns of building occupancy and operations. The use of the EnergyPlus research prototypes did impose some challenges for the research. EnergyPlus is a very sophisticated platform, though it can be much more laborious to manipulate than other modeling tools. The challenges of changing parameter settings within EnergyPlus, particularly for complex HVAC systems, ultimately limited the overall number of design strategies that could be explored through this research. 3.4 Representative Climate Zones The research will optimize building performance for five distinct climate zones. The research will also use the prototypes optimized for CZ12 and simulate their ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 13

15 energy performance in CZ13. Likewise, the optimized prototypes for CZ10 will be modeled using CZ7 weather. Climate Zones 15 Palm Springs Hottest climate bookend 13 Fresno Central Valley climate with less nighttime cooling 12 Sacramento Starting climate for the research; more nighttime cooling 10 Riverside Warmer inland climate 7 San Diego Mild coastal climate south 3 Oakland Mild coastal climate north 16 Blue Canyon Coldest climate bookend (Sierras) Reference Year 2020 is used as the focal point for the commercial analysis as well as the residential analysis, even though the commercial ZNE target is The use of 2020 as the universal analytical point is due, in large measure, to the challenges of projecting system performance levels and measure costs beyond At the modest pace that the construction industry moves new technologies to market, most of the systems in a market ready ZNE design in 2020 are likely to be in early stages of development and testing today. The research team has used that information to make estimates of performance and price in With the complications that are likely to be involved in moving commercial construction to a ZNE standard, assessing what gains can reasonably be made by 2020 will be an important progress indicator. ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 14

16 4 Methodology The objective of the research was to minimize the overall TDV of the buildings energy usage, focusing primarily on energy efficiency. The research was conducted, largely, in the same manner that the research firms design high performance buildings for standard ZNE or high performance construction projects. In this way, the research borrowed heavily from the experience of the lead engineering firms. Design contributions, modeling methodologies, and assumption validations came from around the world via Arup s internal knowledge sharing network. Davis Energy Group and Sun Light and Power have also worked on a number of Zero Net Energy projects in recent years and have incorporated the lessons from those projects into this research. 4.1 Efficiency First, Then Renewables In designing the ZNE or near ZNE prototypes described in Objective I, the research teams prioritized energy reduction measures as follows: Stage: Design Focus: Example: Step 1 Reduce Loads Triple-silver low-e fenestration Step 2 Passive Systems Natural ventilation Step 3 Active Efficiency Chilled beams Step 4 Energy Recovery Integrated heat pump water heater w/ AC Step 5 Onsite Renewables Roof-top photovoltaics Step 6 Cogeneration Fuel-cells for taller buildings (Note: Many design strategies span multiple categories.) This prioritization of the design process matches the priorities embedded in the State's loading order. That loading order views efficiency as the primary tool for meeting California's energy needs, followed by renewable energy production. Although the Technical Feasibility Study is looking to establish the technical feasibility for ZNE design regardless of cost, this staged design methodology includes the added benefit of focusing design efforts first on those solutions that are likely to have the lowest life-cycle costs. The analysis combined parametric modeling, professional experience, and industry practice derived from case studies to determine the best design strategies. The research also benefited from the input of the IOUs, the Project Advisory Group, and other contributors. While the objective of the research was to minimize energy use without adhering to a strict cost effectiveness test, the research made every effort to implement technologies and design solutions that ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 15

17 already are widely available or could be made widely available with likely future improvements Measures Tested, But Not Implemented The exemplar prototypes outlined in this report represent the final cut of the design process. Far more measures, strategies, adjustments, and schedule assumptions were tested and eventually left behind than were incorporated into the final models. These measures include: Radiant cooling in the Medium Office [VAV outperformed radiant at low sensible loads] Insulated residential roof deck [performance and constructability were found superior with ducts in conditioned space and insulation at ceiling] Lower SHGC levels were tested on the office [found to decrease overall performance when paired with widow shading] Solar thermal was explored [equal or better energy offsets were achieved with PV, while utilizing only one solar renewable system (PV) simplifies constructability] Sawtooth daylighting configurations were investigated for some of the commercial roofs [heating and cooling penalty outweighed the daylighting advantages] Dynamic glazing products [the SHGC to VT balancing properties of high performance low-e windows were thought to come close to matching the performance of dynamic glazing, while presenting fewer constructability and maintenance issues] Measure Costs Measure costs will be reported in the final draft. Because this research is not directly constrained by issues of cost effectiveness, cost estimates were not considered in developing the exemplar models. The cost of many of the measures in the exemplar prototypes are easy to estimate. There are a few measures, however, where the cost can be highly variable depending on the method of implementation. Natural ventilation is likely the most challenging measure to cost due to the diversity of ways to implement a successful natural ventilation strategy and challenges of establishing an appropriate cost comparison baseline. 4.2 Renewable Energy and Combined Heat & Power A range of renewable energy systems are covered in the analysis: rooftop photovoltaics, parking lot photovoltaics, and solar thermal systems. Window overhang photovoltaics were also analyzed. The research looked into the benefits ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 16

18 of combined heat and power systems on buildings that were unlikely to reach ZNE targets using onsite photovoltaics. The window overhang photovoltaics and solar thermal systems both help reduce the overall energy use of the buildings, but the benefits generally do not appear sufficient to recommend universal usage at this time. The solar thermal, in particular, would appear to be best replaced with heat pump water heating systems powered by photovoltaics. Much of the Zero Net Energy residential market is moving in this direction. Alternately, the metrics for netting overall energy use could allow excess PV production to offset the required water heating thermal loads Photovoltaic Systems Photovoltaic systems were analyzed in a number of configurations: 1. Commercial rooftop installations 2. Parking lot installations using a single-axis tracker 3. Building integrated window shading installations 4. Residential installations Our standard assumption across all building types was that 80% of the south facing roof was available for the installation of photovoltaic systems. This number was reduced to accommodate skylights in the models. With creative installation practices and roof design strategies, the research finds that photovoltaic systems will offset the loads of the exemplar ZNE prototypes in most cases. Window overhang PV installations did not prove sufficiently beneficial to include in any of the models at present. There are certainly circumstances in taller buildings where they might prove fruitful in closing the consumption / production gap. Although the residential prototype has a roof with four hips to make it orientation neutral, the PV modeling assumed that the roof had a ridgeline running east to west with two gables. Similarly, the PV modeling assumed that the Multifamily Lowrise building had a flat roof even though the prototype had a sloped roof. Both roof types are seen in California Photovoltaic Performance Assumptions A key challenge of ZNE from the perspective of renewable energy systems is power density. A combination of panel optimizers, panel efficiency, and improved racking will continue to increase the overall production of energy for each square foot of available space. This study considered 80% of a building s total roof space available for PV installations. Panels are sloped at 10% for commercial applications and spaced at ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 17

19 15% (counted as panel space usage when progressing to 80% roof usage). Panels are sloped at 20% for the single family residence without spacing. The modeling used 20% efficient panels, and assumed a further 20% increase (to 24% efficiency) by % of additional production was assumed to come from panel optimizers integrated with the system. The PV production numbers also assume an average degradation of 10% over the system lifetime. These performance adjustments amount to over 58% greater production than is observed with standard, 15% efficient panels generally installed today. The solar reporting by building type indicates the amount of solar that would need to be installed, in kw of capacity, to get to ZNE using a Site-kBtu or a TDV metric. The above noted efficiency improvements do not change the required amount of kw that needs to be installed, but the efficiency improvements do impact the necessary space needed to achieve a given kw target The Future of PV While it is difficult to predict the future for solar PV, there is promise for notable improvements in the technologies production efficiency. The best production modules only operate at 20% efficiency now, leaving significant room for improvement. Most of the efficiency improvements in the last decade were due to relatively small incremental advances. Ten years ago, average module efficiencies were in the 12% range; now they are up to about 15%, which is about a 25% improvement in ten years. If this pace of efficiency improvement is maintained, up to 18% or even 20% average module efficiency may be achieved by Clearly, a breakthrough technology could skew this significantly. Top performing modules, rather than average modules, could easily reach the 24% efficiency levels estimated for this technical feasibility research. The real breakthrough for PV in recent years has been in cost reduction. Price points for crystalline solar PV modules in 2012 are at about half of what they were in 2010 and about a quarter of the prices from Wholesale module prices are now in the range of $0.80/W. Large-scale PV projects in some areas are now under $2.00/W installed. Prices for the systems assessed for this report already range as low as $3.00/W installed for a 500 kw system. The industry has recognized for quite some time that the potential for systems cost savings is shifting from module prices to BOS (Balance of System) costs. Costs for racking, inverters and installation are all dropping annually. Array efficiency is now being improved through the use of module optimizers, thereby increasing the net kwh production of a given array. Average improvements on the order of 10% could be achieved in the next few years from these devices Parking Lot Photovoltaics Parking lots across the state represent a significant opportunity for energy production. PV systems installed over parking spaces can produce behind the ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 18

20 meter energy for their associated building property and provide shading to vehicles (there is even secondary energy savings for a car s A/C system). Parking lots have been utilized on a number of ZNE projects to date, including NREL s Zero Net Energy Research Support Facility. A coarse estimate of parking lot sizes associated with each building type is provided below. The final Site-kBtu and TDV$ production numbers relate parking lot production at 35% overall parking coverage to the square feet of the corresponding prototype building: Solar PV on Parking Lots Total Building Area (ft 2 ) Average Parking Spaces kwh/ bldg-ft 2 Site kbtu/ bldg-ft 2 TDV$/ bldg-ft 2 Grocery 45, $76.42 Hospital 241, $15.64 Large Hotel 122, $12.65 Multifamily Highrise 84, $26.52 Multifamily Lowrise 14, $22.83 Large Office 498, $27.99 Medium Office 53, $61.16 Sit Down Restaurant 5, $ Secondary School 210, $24.78 Strip Mall 22, $ Single Family 2,100 N/A N/A N/A N/A Warehouse 49, $17.81 Notes: kwh/space estimated to average 3800 kwh/yr, with the high level of performance coming through the use of trackers, high efficiency, optimizers, and other performance improvements through Two methods were used to calculate average parking lot sizes. Satellite map views of parking lots in Berkeley, Fresno, and San Diego were collected for each building type. Parking lot sizes for each city varied: the more urban Berkeley and San Diego areas had generally smaller lots than Fresno. Lot sizes (in ft 2 ) across the three cities were averaged to produce an estimated number of spaces available. We referenced a Los Angeles zoning ordinance as the second parking lot data point. These two data sources were surprisingly consistent, and an average of the two was taken to produce the final estimate. Based on these parking space estimates, the building types that offer the most energy production potential include large offices, schools, hospitals, and grocery stores. Note that in more urban areas, buildings often have parking structures and therefore only a portion of the spaces (those on the roof of the garage) would be available for PV installation. Although on a parking structure, something closer to 100% coverage of the top deck might be feasible, as compared to the 35% assumed here for ground level parking ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 19

21 Our modeling assumed tracking PV systems in parking lots, covering approximately 1/3 of the available space. The tracking systems both increase overall yield per installed watt and spread production across a wider range of hours. Tracking systems will help offset loads during evening peaks Parking Lot Net Impacts While it is important to consider the use of parking lots for renewable energy production when working on a ZNE project, parking lots inevitably facilitate transportation via cars, which could make parking lots a net energy consumer, even if covered with a photovoltaic system Solar Thermal Solar thermal systems were analyzed, but PV was generally considered a better strategy in the context of this study for offsetting consumption loads. The energy produced by solar thermal systems on a per square foot basis is comparable to that of PV systems (from a source energy perspective), and consequently many ZNE projects may prefer a solar thermal system for thermal applications over a PV system. Policy decisions on how PV production can offset thermal loads being met by onsite natural gas combustion will have a significant impact on the role of solar thermal systems in meeting the State s ZNE goals Notes on Solar Thermal Simulations Simulations for the solar water heating analysis were performed on PolySun modeling software to determine 8760 data. This program uses TMY3 weather data and simulates hourly loads based on numerous heat loss and gain factors. Typically, attempts are made to understand the domestic hot water heating system as a whole, but in this case, efforts have been made to isolate the delivered energy to the system. The following assumptions were made: 1. On demand back up (aux) water heating with heat losses were subtracted out of the calculation. This way one can assume cleaner delivered energy from solar to the designated hot water heating system loads. 2. For all but the single family simulations, a recirculation system was assumed in place with aquastat control. 3. Efforts were made to provide 70% solar fraction on all simulations (offsetting approximately 70% of the domestic hot water load). 4. Location specific cold water temperatures were utilized. This varies greatly between climate zones and is responsible for a large part of the performance difference between the climate zones. ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 20

22 The Future of Solar Thermal For standard flat plate glazed solar collectors, the conversion rate for solar energy to delivered heat is already at quite a high level and therefore efficiency is not likely to improve greatly. There is however room for improvement through the use of lower-cost materials, primarily plastics and polymers, if temperature resistance and durability issues can be overcome. Today there are more product standards and they are of better quality. It is possible that unglazed collectors will be able to be made more useful in seasonal process heat applications, especially where the heat is mainly needed in the summer months (e.g. food processing). A very low-cost unglazed solar water heating kit is on the market that uses unglazed plastic collectors and ties into the existing water heater Combined Heat and Power Combined heat and power (CHP) systems were assessed for buildings where rooftop PV and parking lot PV could not meet the ZNE performance target. CHP systems were sized to meet the remaining load after PV offsets. The following assumptions were used: CHP Component: Modeling Assumption: Electric efficiency: 40% Thermal efficiency: 60% conversion of waste heat System sizing: 70% of time at full load (sized at 30 th percentile hourly kwh) Load tracking: Electric load CHP is applied to relatively few buildings, and due to the system sizing assumptions, CHP performance affects only a small portion of the load in the applicable buildings. CHP is not renewable energy, since it needs fossil fuels to run. Consequently, even as a CHP system reduces TDV usage (a source energy metric), it increases a building s Site-kBtu. CHP systems might also increase carbon emissions in California compared to grid supplied power and a condensing boiler. Once again, this is a product of California s comparatively low carbon-per-kwh electricity supply. How CHP systems fit into the State s overall ZNE objectives needs further analysis. CHP systems improve overall system efficiencies through the use of otherwise wasted heat from electricity production. They may serve a particularly useful role in urban environments where potential uses for the waste heat are more likely to be proximate to the CHP system. Photovoltaic or solar thermal systems are also more difficult to install at scale in urbanized areas. 4.3 Key Research Inputs and Assumptions The research used the following assumptions and inputs: ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 21

23 Design, purchasing, and installation is optimized to minimize energy use, but occupants will use the buildings in the manner that average occupants use a building. o Occupant densities and behavior patterns affect an energy model through the schedules utilized in the modeling process. These schedules define at what fraction of full power a particular building component is utilized for each hour of the simulation. o This research used the standard schedules provided with the commercial research prototypes by the Department of Energy, which are, in turn, informed by CBECS and other occupant pattern research efforts. The residential schedules are derived from the standard Building America energy modeling assumptions incorporated into BEopt, with is also a product of the Department of Energy. The overall building shape of the research prototypes was kept constant (as developed by DOE or other sources) to facilitate research comparisons. This limitation also acts as a proxy for site and client design restrictions. o Manipulating the form of the buildings, to better facilitate daylighting and natural ventilation, would likely lead to even greater energy efficiency. It could, however, decrease the solar installation potential of a building by increasing the perimeter area of the roof that must be kept clear. Such a decrease in available PV space would have a non-trivial impact on the net energy use of the building. 80% of the non-skylight roof area is available for solar power installations. This will require creative racking systems on roofs with significant mechanical systems. Natural ventilation systems will operate close to optimally. Further initiatives might be required to improve the prospects for such an outcome in the field. Models were optimized for TDV in terms of minimizing direct energy consumption. Cost effectiveness was not a restriction on design decisions, although every effort was made to recommend widely implementable design strategies. A key driver in the selection of design strategies was looking to the technologies and strategies used by the pioneering ZNE buildings being designed and constructed today. Arup, Davis Energy Group, Sun Light and Power, and the New Buildings Institute all have exposure to Zero Net Energy projects or near Zero Net Energy projects, and through that exposure have come to understand many of the most promising mix of measures to reach a ZNE target. ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 22

24 Equipment is often specified with performance levels above federal minimums. Plug loads were adjusted by consulting a number of internal and external sources, with the New Building s Institute providing leadership on the office plug load assumptions. Projected plug load reductions were most significant in building types where the research team thought improvements could be most readily implemented. o The research assumed close to a 50% reduction in office plug loads, with an even greater reduction in nighttime loads through robust auto-off controls. o The research assumed a 20% reduction in residential plug loads through efficiency improvements at the equipment level (offset by minor increases in equipment volume). o The research assumed no improvement in the plug loads for hospitals. It was impossible to project if the increasing efficiency in hospital equipment would offset the growing density of such equipment. Issues of density were not explored. Density strategies can range from better desk space allocation systems to making traditionally interior spaces into exterior spaces, such as covered circulation areas within schools. This reduces the overall conditioned floor area while providing the same functionality. ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 23

25 5 Exemplar Prototypes The results of the research are as follows, presently reported for seven prototypes: 5.1 Single Family Residential Single Family Residential Size: 2,100 ft 2 Number of Floors: kbtu/ft 2 /yr 1 floors Climate Zones Load: Solar: Net: TDV/ft 2 (30yr NPV) Load: $11.85 $9.75 $10.33 Solar: -$ $9.75 -$10.33 Net: $0.00 $0.00 $0.00 The single family model is a 2,100 ft 2 single story detached home with 3 bedrooms and 2 bathrooms. The building is orientation neutral with both walls and windows equally distributed. The model is based on the Prototype C used in the Title Residential Alternative Calculation Methodology Manual. The 2013 Title-24 Package A prescriptive measures were used to define the base case building including envelope, HVAC, & DHW characteristics. Per Package A, in climate zones 10 & 12 nighttime ventilation cooling is a base case measure, in the form of a whole house fan. The exemplar model upgrades this measure to integrated nighttime ventilation with a variable speed fan and automatic operation including temperature sensing and setpoint control. Ventilation cooling can also be beneficial in coastal and mountain climates where minimal cooling loads allow it to replace compressor cooling all together. TDV annual energy savings of better than 45% are achieved through deep reductions in building load both with envelope measures and internal load reductions, and with high efficiency mechanical equipment. An important characteristic of the exemplar single family building is that all ductwork is located within conditioned space. Typically, in homes with vented attics the HVAC equipment and associated ductwork is located in the attic and exposed to extreme temperatures, especially during the summer months, resulting in significant energy penalties due to both conduction losses and air leakage. Re-locating the ductwork inside the home s envelope by itself provides ~30% HVAC site and ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 24

26 TDV energy savings. Another equivalent solution is ductless systems such as distributed fan coils, mini-split heat pumps, and radiant systems. A component of the exemplar specification is a combined hydronic system for space heating and DHW. Available capacities of traditional gas furnaces are not well suited for the low heating loads in the exemplar model in all climate zones. It is noted that the performance target established with the combined hydronic system can be obtained through other strategies inclusive of heat pumps. While substantial reductions were made to the majority of end-uses, considerable uncertainty surrounds miscellaneous electrical use and to what degree annual energy use can be reduced by The difficulty in accurately estimating savings potential is in correctly accounting for continued growth of plug load saturation in homes, codes & standards development and market trends that increase efficiency of electronics & appliances, occupant behavior and advanced control strategies. Based on a literature review, this analysis applies an average plug load annual energy use savings of 20% to the exemplar home. The primary basis of this assumption is that some building level control of non-critical loads is employed. With ideal consumer purchasing and behavior patterns there is potential to reduce this number significantly lower, perhaps beyond 50%. The exemplar lighting package assumes 100% LED fixtures with an improved efficacy above that of current technology. Research by the Department of Energy asserts with relative confidence that by 2020 efficacy of LED fixtures will be greater than 200 lumens/watt; this efficacy was used in the exemplar cases. ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 25

27 Single Family Residential CZ12 Sacramento 1 2 Strategy kbtu/ft2/yr incremental savings TDV/ft2 (30 yr) incremental savings TDV cumulative percent reduction Starting EUI: 30.3 $ % Improved Wall Construction: 2x6 walls, R-21 w/ R-4 rigid ext. sheathing. Advanced framing, 24" o.c $1.12 6% Ceiling Insulation: R-60 blown-in insulation w/ raised heel trusses $0.23 7% 3 Reduced Building Infiltration: 1.8 SLA / 3.15 ACH $0.24 9% 4 Improved Windows: U-Factor=0.25 / SHGC= $ % 5 Cool Roof: Reflectivity=0.40 / Emissivity= $ % 6 Additional Thermal Mass $ % 7 N/A 11% 8 N/A 11% Improved Lighting: High efficacy LED lighting and vacancy 9 controls $ % High Efficiency Appliances: Clothes washer, Dishwasher, Refrigerator $ % Reduced Plug Loads from Improved Equipment Efficiency and Controls $ % 12 Low-Flow Shower & Sinks $ % 13 Ducts in Conditioned Space $ % High Efficiency 2-speed AC, SEER 21 w/ Integrated Ventilation 14 Cooling $ % 15 Condensing Gas Space Heating $ % 16 Condensing Gas Water Heater $ % Improved HW Distribution: Compact Design, Insulated HW 17 Pipes $ % 18 Rooftop photovoltaic $ % Ending EUI: 0.0 $0.00 ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 26

28 Single Family Residential CZ Incremental Reductions by Measure EUI TDV $20 $18 $16 $14 $12 $10 $8 $6 $4 $2 $0 ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 27

29 Single Family Residential CZ15 Palm Springs 1 2 Strategy kbtu/ft2/yr incremental savings TDV/ft2 (30 yr) incremental savings TDV cumulative percent reduction Starting EUI: 27.9 $ % = Improved Wall Construction: 2x6 walls, R-21 w/ R-4 rigid ext. sheathing. Advanced framing, 24" o.c. = $1.51 6% = Ceiling Insulation: R-60 blown-in insulation w/ raised heel trusses = $0.27 7% 3 = Reduced Building Infiltration: 1.8 SLA / 3.15 ACH50 = $0.38 8% 4 = Improved Windows: U-Factor=0.25 / SHGC=0.20 = $0.13 9% 5 = Cool Roof: Reflectivity=0.40 / Emissivity=0.85 = $ % 6 N/A 10% 7 High Reflectivity Walls: Reflectivity=0.70 / Emissivity= $ % 8 N/A 12% = Improved Lighting: High efficacy LED lighting and vacancy controls = $ % = High Efficiency Appliances: Clothes washer, Dishwasher, Refrigerator = $ % = Reduced Plug Loads from Improved Equipment Efficiency and Controls = $ % 12 = Low-Flow Shower & Sinks = $ % 13 = Ducts in Conditioned Space = $ % 14 = High Efficiency 2-speed AC, SEER 21 w/ Integrated Ventilation Cooling = $ % 15 N/A $ % 16 = Condensing Gas Water Heater = $ % = Improved HW Distribution: Compact Design, Insulated HW 17 Pipes = $ % 18 = Rooftop photovoltaic = $ % ( == bracketing indicates same measure as CZ12) Ending EUI: 0.0 $0.00 ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 28

30 Single Family Residential CZ16 Blue Canyon 1 Strategy kbtu/ft2/yr incremental savings TDV/ft2 (30 yr) incremental savings TDV cumulative percent reduction Starting EUI: 42.5 $ % Improved Wall Construction: Double stud walls, R in. depth, 24" o.c $1.44 7% = Ceiling Insulation: R-60 blown-in insulation w/ raised heel 2 trusses = $0.31 9% 3 = Reduced Building Infiltration: 1.8 SLA / 3.15 ACH50 = $ % 4 Improved Windows: Triple Pane U-Factor=0.17. High SHGC on North/South & Low SHGC on East/West $ % 5 N/A 20% 6 N/A 20% 7 N/A 20% 8 R-10 Underslab Insulation $ % 9 10 =Improved Lighting: High efficacy LED lighting and vacancy controls = $ % = High Efficiency Appliances: Clothes washer, Dishwasher, Refrigerator = $ % = Reduced Plug Loads from Improved Equipment Efficiency and 11 Controls = $ % 12 = Low-Flow Shower & Sinks = $ % 13 = Ducts in Conditioned Space = $ % High Efficiency AC, SEER 14, 12 EER per Fed. Efficiency 14 Standards $ % 15 = Condensing Gas Space Heating = $ % 16 = Condensing Gas Water Heater = $ % = Improved HW Distribution: Compact Design, Insulated HW 17 Pipes = $ % 18 = Rooftop photovoltaic = $ % ( == bracketing indicates same measure as CZ12) Ending EUI: 0.0 $0.00 ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 29

31 4 Pacific Gas & Electric Company Building Performance Data Single Family Residential Climate Zones Square feet: 2, Total Building Energy Metrics kwh/ft 2 Minimized Site-kBtu Load kw/bldg (250 hr method) Minimized TDV Load Minimized Site-kBtu Minimized TDV Therms/ft 2 Load Carbon Carbon (lbs/ft 2 ) Minimized Site-kBtu Minimized TDV Solar Capacity Solar PV (kw) Minimized Site-kBtu Minimized TDV Peak Export (kw - bldg) Empty Avail. Roof (ft 2 ) Minimized Site-kBtu Minimized TDV Minimized Site-kBtu Minimized TDV Building Height Analysis Floors at ZNE Floors with Parking PV ZNE w Site Metric ZNE w TDV Metric ZNE w Site Metric ZNE w TDV Metric Park. PV Size (kw) "Site kbtu" = Site kbtu/ft2/yr "Minimized" = As much PV as is necessary to reach ZNE, but not beyond. PV capacity is also capped by available roof Parking PV only considered in final rows. ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 30

32 kwh by Bin Single Family Residential May through October Mon. - Fri. Sat. - Sun. Climate Zones Load Solar Net Load Solar Net Load Solar Net 21:00-6: :00-9: :00-12: :00-15: :00-18: :00-21: :00-6: :00-9: :00-12: :00-15: :00-18: :00-21: Gas Therms November through April Mon. - Fri. Sat. - Sun. 21:00-6: :00-9: :00-12: :00-15: :00-18: :00-21: :00-6: :00-9: :00-12: :00-15: :00-18: :00-21: Gas Therms ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 31

33 5.2 Multi-Family Low-Rise Multi-Family Low-Rise Size: 14,700 ft 2 Number of Floors: 3 floors kbtu/ft 2 /yr Climate Zones Load: Solar: Net: TDV/ft 2 (30yr NPV) Load: $19.42 $14.58 $15.15 Solar: -$ $ $15.15 Net: $0.00 $0.00 $0.00 The multi-family low-rise model is a 3-story building with twelve 1,225 ft 2 3-bed, 1-bath units and exterior entrances. The building is orientation neutral with both walls and windows equally distributed. With the exception of ventilation cooling, the base case is identical to that for the single family, which is based on the 2013 Title-24 Package A prescriptive measures. Because of venting difficulties in multi-family buildings, whole house fans are not included in the prescriptive package. However, in the exemplar model this analysis does include an integrated ventilation cooling system in certain climates. Major differences between single family and low-rise multifamily are the inclusion of a heat recovery ventilator (HRV) for mechanical ventilation, central gas water heating, and drainwater heat recovery off showers. With higher cooling loads in the multifamily case due to reduced exterior walls and windows for heat rejection, the HRV provides considerable TDV energy savings. However, on a site basis the increased fan energy does not offset heating and cooling savings. Central gas water heating is a common strategy for water heating employed in many multifamily buildings. Centralizing the source simplifies installation in that gas lines and venting do not need to be run to and from multiple points within the building. It does include the addition of a recirculation pump. Proper control of the pump is important to minimize energy use. The exemplar model includes a combination of timer and temperature modulation control. Additional savings can be achieved through demand control operation. When plumbing is laid out in a compact manner and drains are appropriately stacked, drainwater heat recovery has been shown to provide upwards of 30% ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 32

34 water heating savings. For this evaluation, it is assumed that effective recovery is only captured from the shower drains providing 10% water heating savings. Multi-Family Low-Rise Residential CZ12 Sacramento 1 2 Strategy kbtu/ft2/yr incremental savings TDV/ft2 (30 yr) incremental savings TDV cumulative percent reduction Starting EUI: 30.7 $ % Improved Wall Construction: 2x6 walls, R-21 w/ R-4 rigid ext. sheathing $0.18 1% Ceiling Insulation: R-60 blown-in insulation w/ raised heel trusses $0.06 1% 3 Reduced Building Infiltration: 1.8 SLA / 3.15 ACH $0.16 2% 4 Improved Windows: U-Factor=0.25 / SHGC= $0.40 3% 5 Cool Roof: Reflectivity=0.40 / Emissivity= $0.03 3% 6 Additional Thermal Mass $0.20 4% Improved Lighting: High efficacy LED lighting and vacancy 7 controls $ % 8 Large Appliances: Clothes Washer, Dishwasher, Refrigerator $ % 9 Reduced Plug Loads from Improved Equipment Efficiency and Controls $ % 10 Low-Flow Shower & Sinks $ % 11 Ducts in Conditioned Space $ % 12 High Efficiency 2-speed AC, SEER $ % 13 Integrated Ventilation Cooling $ % 14 Condensing Space Heating $ % 15 Condensing Gas Water Heater $ % 16 Shower Drainwater Heat Recovery $ % 17 Rooftop PV $ % Ending EUI: 0.0 $0.00 ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 33

35 Multi-Family Low-Rise Residential CZ Incremental Reductions by Measure EUI TDV $30 $25 $20 $15 $10 $5 $0 ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 34

36 4 Pacific Gas & Electric Company Building Performance Data Multi-Family Low-Rise Climate Zones Square feet: 14, Total Building Energy Metrics kwh/ft 2 Minimized Site-kBtu Load kw/bldg (250 hr method) Minimized TDV Load Minimized Site-kBtu Minimized TDV Therms/ft 2 Load Carbon Carbon (lbs/ft 2 ) Minimized Site-kBtu Minimized TDV Solar Capacity Solar PV (kw) Minimized Site-kBtu Minimized TDV Peak Export (kw - bldg) Empty Avail. Roof (ft 2 ) Minimized Site-kBtu Minimized TDV Minimized Site-kBtu 1,360 1,462 1,387 Minimized TDV 1,535 2,078 2,124 Building Height Analysis Floors at ZNE Floors with Parking PV ZNE w Site Metric ZNE w TDV Metric ZNE w Site Metric ZNE w TDV Metric Park. PV Size (kw) "Site kbtu" = Site kbtu/ft2/yr "Minimized" = As much PV as is necessary to reach ZNE, but not beyond. PV capacity is also capped by available roof Parking PV only considered in final rows. ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 35

37 5.3 Medium Office Medium Office Size: 53,600 ft 2 Number of Floors: kbtu/ft 2 /yr 3 floors Climate Zones Load: Solar: Net: TDV/ft 2 (30yr NPV) Load: $23.43 $18.44 $17.09 Solar: -$ $ $17.09 Net: $0.00 $0.00 $0.00 The medium office shows promise of being a ZNE building type in Due to its deep floor plate, the building s overall energy use is driven primarily by internal loads and not envelope loads. A combination of lighting technology improvements, smart equipment specifications, and a robust use of demand-side controls to turn off unused devices can have a dramatic effect on overall internal gains within an office. The New Buildings Institute has found that office plug loads are often running at 50% of capacity through the middle of the night. These background loads, often serving no notable purpose, are a primary target for occupancy controls, timers, software for better computer system management, and offsite server virtualization. That reduction in internal loads moves the building to a more neutral stance for California s climates, such that heating demand and cooling demand are much more evenly balanced. In that more neutral position, passive systems can be used to maintain occupant comfort. Those passive systems include the use of natural ventilation, additional thermal mass, and passive solar design. Some mechanical ventilation was still used in the model, even when natural ventilation was suitable, to ensure appropriate airflow via the economizer to the sizable core zone of the building. The HVAC system consists of packaged air conditioning units with a gas furnace inside the packaged DX air conditioning unit. The zone level distribution is VAV with hot water reheat. A dramatic reduction in reheat came about with the introduction of low turndown diffusers on the VAV system. Since the internal loads had been reduced so much, ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 36

38 the perimeter spaces are at a neutral conditioning state for much of the year. A low turndown at the zone allows for the amount of air that needs to be reheated to be greatly reduced. There is still a need within the prototype office models for morning warm-up much of the year, particularly when natural ventilation pre-cooling is implemented at night. This strategy creates a net reduction in TDV usage. A radiant chilled ceiling system was developed and tested for the medium office, but it showed no benefit with the low internal loads as a result of the energy efficient lighting and controlled equipment loads. A high performance VAV system was found to be a better solution that utilizes an airside economizer and low-pressure drop design. ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 37

39 Medium Office CZ12 Sacramento Strategy kbtu/ft2/yr incremental savings TDV/ft2 (30 yr) incremental savings TDV cumulative percent reduction Starting EUI: 32.6 $ % 1 Reduce Lighting Power Density (LPD) by 60% $2.44 8% Reduce nighttime plug load schedule to 0.10, with the use of a Night- 2 Watchman type system on the computers $ % 3 Reduce design plug load level from 1.0 W/sf to 0.5 W/sf $ % 4 Reduced exterior lighting design wattage level by 50% $ % 5 Adjusted WWR from 33% to 30% by raising the sill of the window $ % 6 Added 2 foot overhangs to all facades $ % 7 Changed exterior wall insulation from R-9.73 to R-12.16, 25% over $ % 8 Increased R-value of roof insulation from 19.7 to 24.6 (25% increase) $ % 9 Changed windows to Window_U_0.43_SHGC_ $ % 10 Added PV panel shading on roof $ % 11 Created additional thermal mass (2 inches of concrete) $ % 12 Implemented natural ventilation $ % 13 Changed cooling setpoint from 75.2 F to 77 F during occupied hours $ % 14 Changed electric resistance reheat coils to hot water coils $ % 15 Changed fan efficiency from to $ % 16 Changed boiler efficiency from 0.89 to 0.98 (condensing boiler) $ % Improved water heater thermal efficiency to 0.97 from 0.8 to reflect 17 high efficiency technology currently on market $ % " pressure drop for air distribution $ % COP on DX coils (from 3.4) $ % Reduced minimum turndown on VAV boxes to 10% to represent 20 therma-fuser type diffusers $ % 21 Rooftop PV $ % Ending EUI: 0.0 $0.00 ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 38

40 Medium Office CZ Incremental Reductions by Measure EUI TDV $35 $30 $25 $20 $15 $10 $5 $0 ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 39

41 Medium Office CZ15 Palm Springs Strategy kbtu/ft2/yr incremental savings TDV/ft2 (30 yr) incremental savings TDV cumulative percent reduction Starting EUI: 38.0 $ % 1 =Reduce Lighting Power Density (LPD) by 60%= $3.12 9% =Reduce nighttime plug load schedule to 0.10, with the use of a Night- 2 Watchman type system on the computers= $ % 3 =Reduce design plug load level from 1.0 W/sf to 0.5 W/sf= $ % 4 =Reduced exterior lighting design wattage level by 50%= $ % 5 =Adjusted WWR from 33% to 30% by reducing the height of the windows= $ % 6 Added 4 foot overhangs all facades $ % 7 =Changed exterior wall insulation from R-9.73 to R-12.16, 25% over 90.1= $ % 8 =Increased R-value of roof insulation from 19.7 to 24.6 (25% increase)= $ % 9 Changed windows to Window_U_0.29_SHGC_ $ % 10 =Added PV panel shading on roof= $ % 11 Created additional thermal mass (4 inches of concrete) $ % 12 NA 42% 13 =Changed cooling setpoint from 75.2 F to 77 F during occupied hours= $ % 14 =Changed electric resistance reheat coils to hot water coils= $ % 15 =Changed fan efficiency from to 0.7= $ % 16 =Changed boiler efficiency from 0.89 to 0.98 (condensing boiler)= $ % =Improved water heater thermal efficiency to 0.97 from 0.8 to reflect 17 high efficiency technology currently on market= $ % 18 =2.07" pressure drop for air distribution= $ % 19 =3.5 COP on DX coils (from 3.4)= $ % =Reduced minimum turndown on VAV boxes to 10% to represent 20 therma-fuser type diffusers= $ % 21 = Rooftop PV = $ % ( == bracketing indicates same measure as CZ12) Ending EUI: 0.0 $0.00 ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 40

42 Medium Office CZ16 Blue Canyon Strategy kbtu/ft2/yr incremental savings TDV/ft2 (30 yr) incremental savings TDV cumulative percent reduction Starting EUI: 33.0 $ % 1 = Reduce Lighting Power Density (LPD) by 60% = $2.25 6% = Reduce nighttime plug load schedule to 0.10, with the use of a Night- 2 Watchman type system on the computers = $ % 3 = Reduce design plug load level from 1.0 W/sf to 0.5 W/sf = $ % 4 = Reduced exterior lighting design wattage level by 50% = $ % 5 = Adjusted WWR from 33% to 30% by reducing the height of the windows = $ % 6 = Added 2 foot overhangs to all facades = $ % = Changed exterior wall insulation from R-9.73 to R-12.16, 25% over = $ % 8 = Increased R-value of roof insulation from 19.7 to 24.6 (25% increase) = $ % 9 Changed windows to Window_U_0.25_SHGC_ $ % 10 = Added PV panel shading on roof = $ % 11 = Created additional thermal mass (4 inches of concrete) = $ % 12 NA 28% 13 = Changed cooling setpoint from 75.2 F to 77 F during occupied hours = $ % 14 = Changed electric resistance reheat coils to hot water coils = $ % 15 = Changed fan efficiency from to 0.7 = $ % 16 = Changed boiler efficiency from 0.89 to 0.98 (condensing boiler) = $ % = Improved water heater thermal efficiency to 0.97 from 0.8 to reflect 17 high efficiency technology currently on market = $ % 18 = 2.07" pressure drop for air distribution = $ % 19 = 3.5 COP on DX coils (from 3.4) = $ % = Reduced minimum turndown on VAV boxes to 10% to represent 20 therma-fuser type diffusers = $ % 21 = Rooftop PV = $ % ( == bracketing indicates same measure as CZ12) Ending EUI: 0.0 $0.00 ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 41

43 4 Pacific Gas & Electric Company Building Performance Data Medium Office Climate Zones Square feet: 53, Total Building Energy Metrics kwh/ft 2 Minimized Site-kBtu Load kw/bldg (250 hr method) Minimized TDV Load Minimized Site-kBtu Minimized TDV Therms/ft 2 Load Carbon Carbon (lbs/ft 2 ) Minimized Site-kBtu Minimized TDV Solar Capacity Solar PV (kw) Minimized Site-kBtu Minimized TDV Peak Export (kw - bldg) Empty Avail. Roof (ft 2 ) Minimized Site-kBtu Minimized TDV Minimized Site-kBtu 4,378 5,130 5,173 Minimized TDV 3,800 5,802 6,903 Building Height Analysis Floors at ZNE Floors with Parking PV ZNE w Site Metric ZNE w TDV Metric ZNE w Site Metric ZNE w TDV Metric Park. PV Size (kw) 1,189 1,189 1,189 Site-kBtu" = Site kbtu/ft2/yr "Minimized" = As much PV as is necessary to reach ZNE, but not beyond. PV capacity is also capped by available roof Parking PV only considered in final rows. ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 42

44 May through October kwh by Bin Medium Office Mon. - Fri. Sat. - Sun. Climate Zones Load Solar Net Load Solar Net Load Solar Net 21:00-6:00 10,703-1,535 9,169 7,557-1,220 6, :00-9:00 23,080-22, ,625-16,651-1, :00-12:00 32,614-47,682-15,067 23,477-40,219-16, :00-15:00 37,026-43,840-6,814 27,571-39,356-11, :00-18:00 28,921-15,821 13,100 21,057-17,020 4, :00-21:00 15, ,633 9, , :00-6:00 5,490-1,966 3,525 4,030-1,453 2, :00-9:00 4,322-12,720-8,398 2,740-10,572-7, :00-12:00 4,920-19,366-14,446 3,172-17,255-14, :00-15:00 5,141-14,341-9,199 3,488-13,387-9, :00-18:00 2,975-2, ,007-3,347-1, :00-21:00 2, ,584 1, , Gas Therms November through April Mon. - Fri. Sat. - Sun. 21:00-6:00 8, ,652 8, , :00-9:00 11,492-14,323-2,831 10,723-6,410 4, :00-12:00 20,303-42,191-21,888 17,514-24,955-7, :00-15:00 21,651-40,078-18,427 18,009-26,610-8, :00-18:00 18,550-10,581 7,970 15,680-8,683 6, :00-21:00 6, ,003 5, , :00-6:00 3,853-1,011 2,841 3, , :00-9:00 2,286-10,513-8,226 2,088-5,584-3, :00-12:00 2,505-17,911-15,406 2,055-11,960-9, :00-15:00 2,226-13,255-11,028 1,750-9,144-7, :00-18:00 1,711-1, ,487-1, :00-21:00 1, ,582 1, , Gas Therms 930 1,559 0 ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 43

45 5.4 Large Office Large Office Size: 498,600 ft 2 Number of Floors: 12 floors +basement Climate Zones kbtu/ft 2 /yr Load: Solar: Net: TDV/ft 2 (30yr NPV) Load: $22.67 $18.87 $21.14 Solar: -$7.93 -$7.74 -$8.50 Net: $14.74 $11.14 $12.64 The large office is a 12-story 498,600 square foot building. The large office is very similar to the medium office with a deep floor plate and 15 deep perimeter zones. Internal loads were reduced exactly the same as the medium office model with reductions in equipment and lighting loads. Passive energy efficient measures such as natural ventilation, thermal mass, and passive solar design were utilized in the large office model as well. Using natural ventilation in a building of this height creates notable complications in simultaneously complying with the fire code, which can increase first costs. The HVAC system consists of a gas-condensing boiler, two water-cooled centrifugal chillers. The zone level distribution is VAV with hot water reheat. As with the medium office, the large office exemplar model utilizes low turndown on the VAV distribution, which greatly reduces reheat as well as fan energy. A high performance VAV system with airside economizer and low-pressure drop design is a better option than a radiant system for the large office model as well. The central chiller represented the most significant operational change in the model, at COP=6.5. ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 44

46 Large Office CZ12 Sacramento Strategy kbtu/ft2/yr incremental savings TDV/ft2 (30 yr) incremental savings TDV cumulative percent reduction Starting EUI: $ % 1 Reduce LPD to 0.4 W/sf $1.90 6% 2 Reduce EPD to 0.5 W/sf $ % 3 Reduce exterior lighting by 50% $ % 4 Reduced unoccupied plug load to 10% of design value $ % 5 6 Reduced elevator design load by 50% and reduced elev fan and lights by 60% $ % Changed exterior wall insulation from R-6.33 to R-8, 25% over $ % 7 Increased R-value of roof insulation from 19.7 to 24.6 (25% increase) $ % 8 Changed windows to Window_U_0.43_SHGC_ $ % 9 Added PV panel shading on roof $ % 10 Added 2 foot overhangs to all facades $ % 11 Created additional thermal mass (4 inches of concrete) in all zones $ % 12 Implemented natural ventilation $ % 13 Changed cooling setpoint from 75.2 F to 76 F during occupied hours $ % Reduced fan pressure drop from 5.58 in wc to 3.0 in wc (through use 14 of low-pressure design, therma-fusers) $ % 15 Changed boiler efficiency from 0.89 to 0.97 (condensing boiler) $ % Reduced minimum turndown on VAV boxes to 10% to represent 16 therma-fuser type diffusers $ % 17 Changed fan efficiency from to $ % 18 Improved water heater thermal efficiency to 0.97 from 0.8 to reflect high efficiency technology currently on market $ % 19 Improved COP of chillers from 5.5 to $ % 20 Rooftop PV $ % Ending EUI: $11.14 ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 45

47 Large Office CZ Incremental Reductions by Measure EUI TDV $35 $30 $25 $20 $15 $10 $5 $0 ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 46

48 4 Pacific Gas & Electric Company Building Performance Data Large Office Climate Zones Square feet: 498, Total Building Energy Metrics kwh/ft 2 Minimized Site-kBtu Load kw/bldg (250 hr method) Minimized TDV Load Minimized Site-kBtu Minimized TDV Therms/ft 2 Load Carbon Carbon (lbs/ft 2 ) Minimized Site-kBtu Minimized TDV Solar Capacity Solar PV (kw) Minimized Site-kBtu Minimized TDV Peak Export (kw - bldg) Empty Avail. Roof (ft 2 ) Minimized Site-kBtu Minimized TDV Minimized Site-kBtu Minimized TDV Building Height Analysis Floors at ZNE Floors with Parking PV ZNE w Site Metric ZNE w TDV Metric ZNE w Site Metric ZNE w TDV Metric Park. PV Size (kw) 4,956 4,956 4,956 "Site-kBtu" = Site kbtu/ft2/yr "Minimized" = As much PV as is necessary to reach ZNE, but not beyond. PV capacity is also capped by available roof Parking PV only considered in final rows. ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 47

49 5.5 Secondary School Secondary School Size: 210,900 ft 2 Number of Floors: kbtu/ft 2 /yr 2 floors Climate Zones Load: Solar: Net: TDV/ft 2 (30yr NPV) Load: $40.22 $37.77 $40.05 Solar: -$ $ $40.05 Net: $0.00 $0.00 $0.00 The secondary school is a 2-story structure with classrooms, two gyms, a library, an auditorium, a kitchen, a cafeteria, and offices. It has 30% window-to-wall ratio and a 4% skylight-to-roof ratio in both gyms. Similar to the office model, the school s overall energy consumption is driven primarily by internal loads, such as lighting, equipment, and people. This leads to high cooling energy consumption in all climate zones, except climate zone 16, where heating and cooling energy use is about even. To achieve an exemplar model, the research team focused on improving the envelope of the building, reducing internal loads, testing passive strategies, and adding a more efficient HVAC system. The envelope improvements were based on the Title Standard. The walls, floors, windows, and skylights were all improved to match the requirements of Title 24. These changes resulted in Site-kBtu and TDV improvements in climate zone 12 and 15, and little change in climate zone 16. The equipment loads were not changed because although there is a trend toward more efficient computers and other equipment, there is also likely to be an increase in computer use in the classroom. In the school model, a 60% reduction in lighting power density is assumed due to the development and use of more efficient LED lights. The effect of pop-up skylights was tested, instead of the original horizontal skylights that were in the gyms. These skylights did not have much of an effect on the TDV and EUI. However, by using pop-up skylights, it is perhaps possible to maximize the area available for PV panels on the roof and retain the daylighting benefit from skylights. ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 48

50 Two overhang depths were tested: half the height of the window and the full height of the window. Both overhangs had little effect on the overall Site-kBtu and TDV. A natural ventilation scheme was implemented in the school. The biggest reduction in energy was due to a reduction in fan energy use. For all climate zones, natural ventilation showed an improvement in both Site-kBtu and TDV. The original school model had an air-cooled chiller. Substituting a water cooled chiller resulted in savings in TDV for all climate zones. The school model is still under development and more changes and tests will be done to reduce the Site-kBtu and TDV as much as possible. ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 49

51 Secondary School CZ12 Sacramento Strategy kbtu/ft2/yr incremental savings TDV/ft2 (30 yr) incremental savings TDV cumulative percent reduction Starting EUI: $ % 1 Title : Envelope & Glazing Improvements $0.63 1% 2 60% Reduction in LPD $ % 3 Modeled pop-up skylights $ % 4 Natural Ventilation in all zones $ % 5 Chiller from air-cooled to water-cooled $ % 6 Rooftop photovoltaic $ % Ending EUI: 1.8 $ Incremental Reductions by Measure EUI TDV $60 $50 $40 $30 $20 $10 $0 ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 50

52 Secondary School CZ15 Palm Springs Strategy kbtu/ft2/yr incremental savings TDV/ft2 (30 yr) incremental savings TDV cumulative percent reduction Starting EUI: 55.6 $ % 1 = Title : Envelope & Glazing Improvements = $3.73 6% 2 = 60% Reduction in LPD = $ % 3 = Modeled pop-up skylights = $ % 4 = Natural Ventilation in all zones = $ % 5 = Chiller from air-cooled to water-cooled = $ % 6 = Rooftop photovoltaic = $ % ( == bracketing indicates same measure as CZ12) Ending EUI: 0.0 $0.00 Secondary School CZ16 Blue Canyon Strategy kbtu/ft2/yr incremental savings TDV/ft2 (30 yr) incremental savings TDV cumulative percent reduction Starting EUI: 52.9 $ % 1 = Title : Envelope & Glazing Improvements = 0.88 $0.03 0% 2 = 60% Reduction in LPD = $ % 3 = Modeled pop-up skylights = $ % 4 = Natural Ventilation in all zones = $ % 5 = Chiller from air-cooled to water-cooled = $ % 6 = Rooftop photovoltaic = $ % ( == bracketing indicates same measure as CZ12) Ending EUI: 7.2 $0.00 ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 51

53 4 Pacific Gas & Electric Company Building Performance Data Secondary School Climate Zones Square feet: 210, Total Building Energy Metrics kwh/ft 2 Minimized Site-kBtu Load kw/bldg (250 hr method) Minimized TDV Load Minimized Site-kBtu Minimized TDV Therms/ft 2 Load Carbon Carbon (lbs/ft 2 ) Minimized Site-kBtu Minimized TDV Solar Capacity Solar PV (kw) Minimized Site-kBtu Minimized TDV Peak Export (kw - bldg) Empty Avail. Roof (ft 2 ) Minimized Site-kBtu Minimized TDV Minimized Site-kBtu 2, Minimized TDV 2,952 5,360 5,679 Building Height Analysis Floors at ZNE Floors with Parking PV ZNE w Site Metric ZNE w TDV Metric ZNE w Site Metric ZNE w TDV Metric Park. PV Size (kw) 1,850 1,850 1,850 "Site-kBtu" = Site kbtu/ft2/yr "Minimized" = As much PV as is necessary to reach ZNE, but not beyond. PV capacity is also capped by available roof Parking PV only considered in final rows. ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 52

54 5.6 Hospital Hospital Size: 241,410 ft 2 Number of Floors: 5 floors +basement Climate Zones kbtu/ft 2 /yr Load: Solar: Net: TDV/ft 2 (30yr NPV) Load: $69.59 $66.65 $64.86 Solar: -$ $ $20.39 Net: $50.56 $48.08 $44.47 The hospital is a 5-story 241,400 square foot building. The space types include: Emergency Room, Office, Lobby, Nurse Station, Operating Room, Patient Room, Physical Therapy, Lab, Radiology, Dining, Kitchen, and Corridors. The hospital has high equipment loads due to the specialized equipment required to operate a healthcare facility. Due to the complexity of this equipment and the fact that by 2020 this equipment will be more sophisticated and is ever-changing, the starting equipment loads have not been altered in the model. Energy efficient LED lighting was modeled as well as occupancy sensors to control lighting at unoccupied hours. Some envelope/passive improvements were implemented but with very minimal effect due to the fact that the hospital model is internal load driven. The greatest improvement in energy usage was achieved through changes in the HVAC system. The baseline energy model HVAC system consisted of a VAV hot water reheat system with electric steam humidifiers serving the medical critical zones. The exemplar model utilizes an active chilled beam system with a dedicated outside air system (DOAS) that includes air-to-air heat recovery; baseboard heaters are also used in perimeter spaces. The role of the DOAS is to supply the minimum required ventilation air to the building. The chilled beams more efficiently handle the high sensible cooling load in the hospital than the VAV reheat system. The main energy improvement with this system is that natural gas consumption for heating is almost completely negated by eliminating reheat at the zone level and greatly reducing heating at the air handling unit (AHU) through the use of heat recovery. ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 53

55 Adjustments for other climate zones are largely identical to climate zone 12 due to the dominance of internal loads in the hospital. ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 54

56 Hospital CZ12 Sacramento 1 Strategy kbtu/ft2/yr incremental savings TDV/ft2 (30 yr) incremental savings TDV cumulative percent reduction Starting EUI: $ % Use 100% LED lighting, 90 lumens per watt is assumed for existing fluorescent, and 150 lumens per watt is new LED, this results in a 40% reduction $4.94 6% 2 Use occ sensors in Office, Lobby, Clinic, OR $0.38 6% 3 Window shades on all facades, 2' $0.01 6% 4 Added PV shading on roof 0.03 $0.05 6% 5 Reduce exterior lights by 40% to represent all LED lighting $0.22 7% 6 7 Reduced elevator design load by 20% and reduced elev fan and lights by 40% $1.61 9% Changed windows from 'Window_U_0.62_SHGC_0.25' to 'Window_U_0.35_SHGC_0.35' $0.11 9% 8 Reduced infiltration rate by 40% $0.01 9% 9 Increased wall insulation by 25% $0.02 9% 10 Reduced patient room's VAV box minimum flow rate to 0.2 from $ % 11 Changed boiler efficiency from 0.89 to 0.97 (condensing boiler) $ % 12 Changed fan efficiency from to $ % Improved water heater thermal efficiency to 0.97 from 0.8 to 13 reflect high efficiency technology currently on market $ % 14 Improved COP of chillers from 5.5 to $ % Reduced fan pressure drop from 5.58 in wc to 3.0 in wc 15 (through use of low-pressure design, therma-fusers) $ % Creted new HVAC system: chilled beams, convective baseboard 16 heaters, DOAS with heat recovery $ % 17 Fixed the chilled water temperature to be 59 F $ % Changed supply air temp from 60 F to 55 F that serves active 18 chilled beams $ % 19 Rooftop PV $ % Ending EUI: 57.5 $48.08 ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 55

57 Hospital CZ Incremental Reductions by Measure EUI TDV $90 $80 $70 $60 $50 $40 $30 $20 $10 $0 ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 56

58 4 Pacific Gas & Electric Company Building Performance Data Hospital Climate Zones Square feet: 241, Total Building Energy Metrics Load kwh/ft 2 Minimized Site-kBtu Minimized TDV Load kw/bldg (250 Minimized Site-kBtu hr method) Minimized TDV Therms/ft 2 Load Carbon (lbs/ft 2 ) Carbon Minimized Site-kBtu Minimized TDV Solar Capacity Minimized Site-kBtu Solar PV (kw) Minimized TDV Peak Export Minimized Site-kBtu (kw - bldg) Minimized TDV Empty Avail. Roof (ft 2 ) Minimized Site-kBtu Minimized TDV Building Height Analysis ZNE w Site Metric Floors at ZNE ZNE w TDV Metric ZNE w Site Metric Floors with ZNE w TDV Metric Parking PV Park. PV Size (kw) 1,322 1,322 1,322 "Site-kBtu" = Site kbtu/ft2/yr "Minimized" = As much PV as is necessary to reach ZNE, but not beyond. PV capacity is also capped by available roof Parking PV only considered in final rows. CHP w/ Parking PV CHP system size (kw) Site-kBtu/ft 2 /yr TDV/ft 2 (30yr NPV) $27.9 -$32.2 $25.9 -$33.4 -$33.4 -$33.2 $23.0 CHP sized to meet 30 th percentile electric load, tracking post-solar electric load. ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 57

59 5.7 Warehouse Warehouse Size: 49,495 ft 2 Number of Floors: 1 floor Climate Zones kbtu/ft 2 /yr Load: Solar: Net: TDV/ft 2 (30yr NPV) Load: $13.07 $10.10 $10.09 Solar: -$ $ $10.09 Net: $0.00 $0.00 $0.00 The warehouse model has 3 zones: 1) Small office, 2) Bulk storage, and 3) Fine storage. All 3 zones are heated and only the fine storage and office zones are cooled. The original model includes 46 skylights (1.5% glazing area) and there are only 4 windows in the office. The non-refrigerated warehouse can achieve ZNE with the help of PV panels. The warehouse model has 7 energy end uses. Depending on the climate zone, the largest energy end uses vary. But interior lighting is a significant part of the total energy across all climate zones. By 2020, LEDs will be widely used in commercial buildings and could likely provide 220 lumens/watt. Based on this assumption, interior lighting energy use was reduced by 60%. This resulted in about 15% reduction in Site-kBtu and about 20% reduction in TDV for all climate zones. To further reduce internal loads, the plug loads in the office area of the warehouse were reduced to 0.5 W/sf and a night-time plug load management system was implemented. The interior equipment in the storage areas was left unchanged due to uncertainty in potential improvements. An analysis was completed on the tradeoff between PV and skylights for the use of roof space. Improving LED efficiency and PV efficiency showed that installing PV in the space that would otherwise be used for skylights would produce three times as much renewable energy as was lost from the decreased daylighting. Although the skylights remained in the prototype, this will be an important design consideration in some buildings with restricted roof areas. ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 58

60 Warehouse CZ12 Sacramento 1 Strategy kbtu/ft2/yr incremental savings TDV/ft2 (30 yr) incremental savings TDV cumulative percent reduction Starting EUI: 15.3 $ % NEW LPD: BS= 0.35 W/sf, FS= 0.57 W/sf, Office= 0.6 W/sf (60% red from 90.1) $ % 2 Lighting Sensor Schedule for Storage (F&B) $ % 3 Reduced Office Plug Load to 0.5 W/sf $ % 4 Reduced Office UnOcc Schedule to 0.1 Fraction $ % 5 Floor Insulation $ % 6 Exterior Lighting: 40% reduction to 54.6 W & W $ % 7 Rooftop PV $ % Ending EUI: 0.0 $ Incremental Reductions by Measure EUI TDV $16 $14 $12 $10 $8 $6 $4 $2 $0 ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 59

61 Warehouse CZ15 Palm Springs 1 Strategy kbtu/ft2/yr incremental savings TDV/ft2 (30 yr) incremental savings TDV cumulative percent reduction Starting EUI: 17.2 $ % = NEW LPD: BS= 0.35 W/sf, FS= 0.57 W/sf, Office= 0.6 W/sf (60% red from 90.1) = $ % 2 = Lighting Sensor Schedule for Storage (F&B) = $ % 3 = Reduced Office Plug Load to 0.5 W/sf = $ % 4 = Reduced Office UnOcc Schedule to 0.1 Fraction = $ % 5 = Floor Insulation = $ % 6 = Exterior Lighting: 40% reduction to 54.6 W & W = $ % 7 = Rooftop PV = % ( == bracketing indicates same measure as CZ12) Ending EUI: 0.0 $0.00 Warehouse CZ16 Blue Canyon 1 Strategy kbtu/ft2/yr incremental savings TDV/ft2 (30 yr) incremental savings TDV cumulative percent reduction Starting EUI: % = NEW LPD: BS= 0.35 W/sf, FS= 0.57 W/sf, Office= 0.6 W/sf (60% red from 90.1) = % 2 = Lighting Sensor Schedule for Storage (F&B) = % 3 = Reduced Office Plug Load to 0.5 W/sf = % 4 = Reduced Office UnOcc Schedule to 0.1 Fraction = % 5 N/A 22% 6 = Exterior Lighting: 40% reduction to 54.6 W & W = % 7 = Rooftop PV = % ( == bracketing indicates same measure as CZ12) Ending EUI: 0.0 $0.00 For CZ 16: Adding Floor insulation results in lower Site-kBtu but higher TDV ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 60

62 4 Pacific Gas & Electric Company Building Performance Data Warehouse Climate Zones Square feet: 49, Total Building Energy Metrics kwh/ft 2 Minimized Site-kBtu Load kw/bldg (250 hr method) Minimized TDV Load Minimized Site-kBtu Minimized TDV Therms/ft 2 Load Carbon Carbon (lbs/ft 2 ) Minimized Site-kBtu Minimized TDV Solar Capacity Solar PV (kw) Minimized Site-kBtu Minimized TDV Peak Export (kw - bldg) Empty Avail. Roof (ft 2 ) Minimized Site-kBtu Minimized TDV Minimized Site-kBtu 29,344 29,727 26,949 Minimized TDV 29,244 30,351 30,618 Building Height Analysis Floors at ZNE Floors with Parking PV ZNE w Site Metric ZNE w TDV Metric ZNE w Site Metric ZNE w TDV Metric Park. PV Size (kw) "Site-kBtu" = Site kbtu/ft2/yr "Minimized" = As much PV as is necessary to reach ZNE, but not beyond. PV capacity is also capped by available roof Parking PV only considered in final rows. ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 61

63 5.8 Multifamily Highrise Under Development (next draft) 5.9 Grocery Under Development (next draft) 5.10 Strip Mall Under Development (next draft) 5.11 Lodging Under Development (next draft) 5.12 Restaurant Under Development (next draft) ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 62

64 6 Costs This is not a study of cost effectiveness. The study will, however, be reporting on the expected costs of the recommended energy efficiency measures and design strategies. That data continues to be collected and will be reported in subsequent project report drafts. A. METHODOLOGY B. ROLE OF COSTS IN MAKING DESIGN DECISIONS 1. SINGLE-FAMILY RESIDENTIAL 2. ALL OTHERS ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 63

65 7 ZNE Scenario Analysis Tool A secondary part of the Technical Feasibility study is the delivery of a dynamic analysis tool to evaluate alternative ZNE design strategies as compared to those recommended and evaluated in the exemplar designs. The scenario analysis tool will have a number of uses for IOU program planning efforts. 7.1 Scenario Analysis Tool Methodology ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 64

66 Scenario Users select a scenario by using sliders, radio buttons and drop-down menus. For energy efficiency measures (EEMs) that have slider inputs, users select a value between high and low bookends. The EEMs that relate to this calculation step are shown below. Load Gradients Thermal gains include internal gains (lighting and equipment) and envelope gains (window and wall) with each EEM having an influence on one or more of the thermal gains. A linear relationship between the EEM setting and its related ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 65

67 thermal gains is established by running two simulations that represent the extreme high and low cases. These cases are as follows. 1) All EEMs set to highest gain settings 2) All EEMs set to lowest gain settings This process is performed on an hourly, per zone, per gain basis. Calculation Rules These rules do not use interpolation to predict the effect of EEMs. EEMs that require calculation rules each have a mathematical function that relates their position in the scenario to their effect on thermal loads or fuel demand. For example, the window overhang EEM has an associated calculation rule that determines how much solar radiation is blocked out on an hourly basis depending on the altitude of the sun. Load Prediction The first calculation is a prediction of loads at the heating and cooling coils of the building, using EEM settings that relate to load reduction and passive systems. There are two types of calculations - those that employ load gradients, and those that employ calculation rules. The pre-calculated load gradients are used to calculate the heating and cooling ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 66

68 loads on an hourly basis by zone, interpolating between the EEM bookends. The EEMs that employ this methodology are marked LG on the scenario diagram. Calculation rules are used to predict the effect of the remaining EEMs. Heating and Cooling Maps These maps correlate coil loads to fuel demand and are generated using hourly simulation data and normalized against peak load. A separate map is generated for different dry-bulb temperature bands. ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 67

69 Auxiliary Systems Gradients These are generated in the same way as the load gradients, and are used to describe relationships between total coil load and auxiliary system energy due to fans, pumps and heat rejection equipment. On-Site Generation Potential This pre-calculated data relates to a particular climate zone s potential for harnessing solar energy for solar thermal and photovoltaic strategies. These sources will be netted out on a yearly, daily, or hourly basis depending on the system type. Fuel Demand Prediction The second calculation is a prediction of fuel demand, using calculated loads and EEM settings that relate to active systems. Heating and cooling maps are used to calculate fuel demand, as a function of coil load, due to heating and cooling systems. Further calculations are required when rule-based EEMs affect these systems. Auxiliary systems gradients are used to calculate fan, pump and heat rejection fuel demand. Further calculations are required where rule-based EEMs affect these systems. On-site generation potential, along with EEM settings relating to solar energy, are used to determine how much energy can be offset using on-site sources. ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 68

70 Graphical Display Aggregation / TDV Calculations Hourly fuel demand values are used to calculate hourly TDV. These values are aggregated and sent back to the interface front-end. ZNE/ Draft 2 November 20, 2012 Arup North America Ltd Page 69