Reed Berinato Mechanical Option. Building and Plant Energy Analysis Report October 27, Contents

Transcription

1 Contents Executive Summary... 3 LEED Green Building Rating Discussion... 4 ASHRAE Standard Introduction to ASHRAE Standard Envelope Compliance... 5 Lighting Compliance... 6 Lost Rentable Space Breakdown... 7 Building Energy Use Summary... 8 Hand Load Calculations... 8 verview of Procedures Used... 8 Lighting and Equipment Power Densities... 9 Envelope Heat Gain... 9 Human ccupancy Load Calculations Approach to obtain Building Load Results & Conclusions Computer Based Modeling Approach to Load Calculations verview of Procedures and Values Used Results & Conclusions Comparison of Hand Load Calculations & HAPv4.1 Model Hand Annual Energy Usage Calculations verview of Procedures and Values Used Results & Conclusions HAP Annual Energy Usage Simulation verview of Procedures and Values Used Results & Conclusions

2 Comparison of Hand Energy Calculations & HAPv4.1 Simulation Emissions Mechanical System Costs Mechanical Equipment Serviceability Appendices Appendix A: Envelope Compliance Details Appendix B: Lighting Compliance Details Appendix C: Lost Rentable Space Details Appendix D: Hand Load Calculation Details Appendix E: HAP Load Calculation Details Appendix F: Hand Annual Energy Calculation Details Appendix G: HAP Energy Simulation details

3 Executive Summary A building plant and energy analysis was preformed on the Jaharis Family Center for Biomedical and Nutritional Research in Boston, Massachusetts. Within the scope of this report is the evaluation for LEED green building rating certification. Due to the domination of laboratory and laboratory support spaces within this building, LEED certification is not applicable. However when compared to a typical building containing laboratory space which uses 85 kwh/ft 2 -year (Energy Efficiency in California Laboratory Type Facilities, Lawrence Berkley July 31, 1996,) the s consumption of 28.3 kwh/ft 2 -year is significantly less. Many facets of this building restricted it from being a green building, including its supply of 100% outdoor air. Included in this report is an examination of ASHRAE Standard certification. The wall and roof assemblies complied with Standard 90.1, and the window assemblies nearly comply. The lighting power densities for the typical spaces examined were also found to be compliant with Standard 90.1 with the exception of the men s restroom. The lost rentable space of the was also found to be 23,051 square feet, or 12.8% of the gross floor area. Equipment serviceability was in scope of this report as well, and was found to be satisfactory. Also, the mechanical systems cost was appraised, and found to be $3,173,400 or approximately $17.63 per square foot of floor area. This report is also a compilation of load and energy estimates performed on the located in Boston, Massachusetts. This nine story building is only fit out on the basement level through level three, so all analyses are performed on these levels only which are served by AHU s 3 & 4. The duct configuration of AHU s 3 & 4 require all analyses to be performed as if they acted as one air handler. Both the load and energy estimation sections of this report involve two methods of calculation. First, a hand calculation is performed, and then a computer based model is employed. The software used in this report is Carrier s HAP v4.01. For the load estimation section of this report, hand calculations utilized design data from ASHRAE Standard along with data acquired from the design documents. The HAP analysis utilized internal weather data included in the software, as well as the data from the design documents. The hand calculation of the building load resulted in a load of 276 tons at 514 sqft/ton, while the HAP analysis determined the building load to be 617 tons at 123 sqft/ton. Actual equipment in the building, including diversity factors, totals 800 tons. The second section of this report, energy estimates, was also completed first using hand calculations then the HAP Software. The hand calculation portion of the energy analysis uses weather data acquired from BinMaker Plus Software. The hand calculations resulted in a total annual operating cost of $121, per year and a cost per square foot of $1.66 per year. The HAP simulation returned a value of $174,150 or $2.29 per square foot. Although an energy report was not available for this building, a comparison is made of the calculated loads and operating costs of the within this report. The difference between the calculated values for load and operating cost using the two different methods are tons and $47, respectively. 3

4 LEED Green Building Rating Discussion LEED, which stands for Leadership in Energy and Environmental Design, has developed a rating system within the building industry. This rating, or point system, promotes more energy-efficient and environmentally friendly building design. This point system is performance based relying on existing practices accepted in the industry as well as new, innovative design techniques. There are five main categories the system is based on including materials and resources, indoor environmental quality, energy and atmosphere, sustainable sites and water efficiency. Within these five categories are subdivisions which are credit based and apply to building performance. nce a building is evaluated under each of these five categories, and all applicable credits are applied to that building, it takes its place within one of the four levels of LEED certification. These four levels consist of LEED certified (26-32 points), Silver Level (33-38 points), Gold Level (39-51 points) and Platinum Level (52+ points) out of 69 possible points. LEED certification is not applicable to the Jaharis Family Center for Biomedical and Nutritional Research. LEED certification is focused mostly on energy-efficient design of office buildings. Although the contains some office space, approximately half of its square footage is dedicated to laboratory space. Because of the strict restrictions placed on laboratory spaces, such as the requirement for 100% outdoor air, this building is much less efficient than it would be if it did not have any laboratory space. Along with the requirement for 100% outdoor air, laboratory space in the Jaharis Center has other inefficiencies such as cold rooms and hot rooms as well as electrical lab equipment. All of these circumstances make a LEED evaluation somewhat unfavorable and out of the scope of LEEDS for the. However,The s consumption of 28.3 kwh/ft 2 -year is 56.7 kwh/ft 2 -year less than that of an average building containing laboratory space(energy Efficiency in California Laboratory Type Facilities, Lawrence Berkley July 31, 1996.) 4

5 ASHRAE Standard Compliance Introduction to ASHRAE Standard ASHRAE Standard is an energy based standard that sets requirements for acceptance in the design of building envelopes, mechanical systems and lighting systems. In order for a building to be in compliance with the standard, it must meet minimum criteria in each of these design areas. The purpose for the standard is to promote energy efficient design. However, in every building designed there is room for exception due to special circumstances. Envelope Compliance In order to rate this building as complaint with ASHRAE Standard , the building s category of climate, space conditioning and class of construction within the standard must first be determined. Using Table D-1 of the Standard (climatic data for ) it was determined that the values of Table B-17 will be used to determine compliance with Standard Table B-17 offers values to be used as a minimum when comparing different aspects of the s design. Within Table B-17, comparative values were chosen under the nonresidential building section using the appropriate opaque element of the buildings construction. The table below shows the compliance of the individual building sections. All assembly component U & R values were determined using the Carrier HAP V4.1 software. A detailed assembly component analysis is located in Appendix A: Envelope Compliance Details located in the final pages of this report. Building elevations were used to estimate the percentage of fenestration for both the entire building and the North elevation. These values were determined to be 15.3% for the entire structure, and 3.4% for the North elevation. The solar heat gain coefficient (SHGC) is calculated based on the shading coefficient (SC) 5

6 found in the window information in the specifications. It can be seen in the summarized envelope compliance table below that all assemblies are in compliance with Standard with the exception of the window assembly U-Value which exceeded the Standard 90.1 maximum allowable value by a differential of.016. Standard Envelope Compliance Construction Type Values Stdandard 90.1 Allowable Values Wall Assemblies Type 1 / Brick Veneer With Stud Backup Type 2 / Brick Veneer With Stud Backup (screen wall) Type 2 / Brick With CMU Backup Roof Assemblies Assembly U- Value Assembly R- Value Maximum Assembly U- Value Minimum Assembly R- Value Assembly U- Value Assembly R- Value Maximum Assembly U- Value Minimum Assembly R- Value Type Type Type Window Assemblies 1" Insulated Glass on Extruded Al Frame Assembly U- Value Assembly SHGC Maximum Assembly U- Value Maximum Assembly SHGC All / North /.49 Lighting Compliance The Space by Space method found in ASHRAE Standard was used in determining the compliance of the project with respect to lighting 6

7 design. Due to the repetition of most space types within the building, only typical spaces were analyzed in this evaluation. The typical spaces evaluated were an office, classroom, cafeteria, conference room and restroom. Although a large percentage of the Jaharis Center consists of laboratory space, the special lighting requirements for such spaces make an evaluation of the compliance with Standard 90.1 somewhat impractical, so all the laboratory spaces within the are excluded from this evaluation. The lighting power densities were calculated by adding up the individual wattages of fixtures and dividing by the total room area. These values were then compared with ASHRAE Table for compliance. The office building model was used as a base for assessing lighting power density compliance with Standard A detailed table of lighting power density calculations is located in Appendix B: Lighting Compliance Details. All spaces evaluated in this report are compliant with Standard 90.1 with the exception of the men s restroom, which was.5 [W/sqft] over the allowable power density set forth by ASHRAE Standard This is most likely due to the incandescent lights in the sink area witch add a considerable amount of power to the space relative to the fluorescent lights. Lost Rentable Space Breakdown Rentable space in a building is a valuable commodity. Space lost to mechanical equipment plays a sizable factor in the design process, and should be considered with any building project. The main mechanical systems in are located in the mechanical penthouse and the basement of the building. The mechanical penthouse is a full two stories tall, but is only considered one-story for the purposes of this evaluation. The total lost rentable space in the due to mechanical space is 23,051 square feet, or approximately 12.8% of the total building area square feet is lost 7

8 due to the mechanical penthouse square feet is lost due to mechanical shafts, and 3114 square feet is lost due to electrical equipment. A detailed table showing each of the individual rentable spaces which are lost can be found in Appendix C: Lost Rentable Space Details at the end of this report. Building Energy Use Summary The is located at a university campus having high pressure steam supply and an electrical generating plant. Along with these energy sources the Center is also connected to the city grid. Depending on the time of year and/or demand, both of these sources are used in different percentages throughout the year. Energy costs are based upon the charge for the use of grid energy. There was no energy analysis done during the design of this mechanical system. All energy usage data in this report is generated by hand calculations or computer energy simulations. Hand Load Calculations verview of Procedures Used The estimated cooling load for the Jaharis Family Center for Biomedical and Nutritional Research was calculated using two different techniques. First, the calculations were done by hand using an Excel spreadsheet. Second, a load analysis was performed using Carrier s Hourly Analysis Program version 4.1. Next, you will find an overview of all the values used in these calculations followed by a brief explanation of the procedures and equations used. 8

9 Lighting and Equipment Power Densities All lighting power densities used in the calculations included within this report include task lighting. Typical offices and task oriented spaces, such as labs, share a lighting power density of 3 W/sqft. Most other non task oriented spaces such as corridors vestibules and storage areas have a typical lighting power density of 1.5 W/sqft. Lobbie areas have a power density of 2 W/sqft. ffices and spaces with computers and phones have equipment power densities of 2 W/sqft; while areas with specialized equipment have densities of 2.5 W/sqft. Spaces lacking equipment such as corridors and vestibules have an equipment power density of 0 W/sqft. Envelope Heat Gain Building envelope heat gain was determined using the U-values found in technical report # 2a, and are located under the equation below. Heat gain through the building s envelope was determined using the equation: Q envelope component = U component A component (T outside -T space ) Uwall =.02 Uroof =.04 Uwindow =.586 Solar loads were not considered in the hand calculation portion of the load estimate of this report. This is one aspect that cannot be ignored in the design of a building, and is looked at in detail in the computer modeling section of the load calculations. 9

10 Human ccupancy Load Calculations Building design maximum occupancies were used in the calculation of the occupant sensible and latent loads. Standard human load values were used, and they are 245 BTU/hr sensible and 205 BTU/hr latent. Approach to btain Building load The total building load was calculated by adding the following loads together: lighting, equipment, outdoor air sensible and latent, occupant sensible and latent, and envelope. The equation s used are as follows: ccupant Sensible: Q = (number of occupants) 245 [BTU/hr] ccupant Latent: Q = (number of occupants) 205 [BTU/hr] From standard Table D-2, the cooling design temperature for Boston, MA was found to be 91 degrees Fahrenheit / 85.5 [gr/bl], and the space design temperatures 75 degrees Fahrenheit / 65 [gr/lb]. A Sensible: Q = 1.08 scfm (Toa 75) A Latent: Q =.68 scfm (Woa 65) Envelope: Q envelope component = U component A component (T outside -T space ) 10

11 The consists of four air handlers. ut of these four air handlers this report examines AHU s 3 and 4. AHU s 3 and 4 are also treated as one air handler due to the looping and connected duct system they share, and the fact that they are perfectly identical. There is no practical way to assign a specific one of these air handlers to a space because they share a common duct system. Also, air AHU 1 & 2 will not be examined because they supply the upper floors of the which have not been outfitted yet. The upper levels of the are shell space, and these air handlers will remain offline until a design is implemented for this space. Results and Conclusions Based on the hand calculations it can be seen that AHU s 3 & 4 share a load of 276 tons. Looking at the load distribution, one can see how the 100% outdoor air design of the has a significant impact on the load. This design fundamental has caused the outdoor air load to attribute for 53% of the total load in the hand calculation. Hand Calculation Load Distribution ccupant Latent 10% A Sensible 30% A Latent 23% ccupant Sensible 12% Envelope 1% Equipment 9% Lighting 15% 11

12 While the occupant, equipment and lighting load comprise most of the other half of the load, the envelope only attributes 1%. nce the solar gain is accounted for, this number may rise. AHU s 3 & 4 Specific Loads [BTU/hr] [ton] Lighting Equipment Envelope ccupant Sens ccupant Latent A Sensible A Latent Total AHU's 3 & 4 sqft / ton cfm / sqft The result of.4 cfm / sqft, and sqft / ton has been obtained during the hand load calculations. Computer Based Modeling Approach to Load Calculations verview of Procedures Used This section of the report calculates building load using the Carrier program: HAP v4.1, and all of the input values described in the hand calculation section. In this computer based calculation method, many more details are taken into account resulting in a more accurate estimation method than hand calculation. Data input into the HAP program was taken from the design documents. Detailed data not used in the hand calculations which are incorporated into this analysis include: ceiling heights, space orientation, solar load, load scheduling, occupancy activity level, geographic location, and climactic data. Climactic data is gathered from the HAP database, and is based on historical data gathered from the area. 12

13 This will help estimate solar loads, outdoor air loads and envelope loads more accurately than using a simple design temperature. Load scheduling may also be a factor causing a difference in result from the hand calculations. Due to the multi-use nature of this building, occupied and unoccupied hours are vaguely defined, but generally this building will be occupied through the hours of 7am to 5pm, and unoccupied cooling will be available. As with the hand calculations, AHU s 3 and 4 will be examined as if the were one unit due to the ductwork configuration that connects these air handlers. Results and Conclusions Air system sizing using the HAP analysis program has resulted in a total cooling load of tons for the. The 100% outdoor air configuration has caused over half of the load to be attributed to outdoor air cooling. The second main contributing load in this analysis is the supply fan. The supply fan contributes 18.8% of the total load. The following table presents some details of the computer analysis. Detailed output data from the HAP program is located in Appendix: B. 13

14 Results and Conclusions (continued) AHU's 3 & 4 Specific Loads [BTU/hr] [ton] Lighting Equipment Envelope ccupant Sens ccupant Latent A Sensible A Latent Duct Heat Gain Zone Conditioning Supply Fan Load Total AHU's 3 & 4 sqft / ton cfm / sqft A Sensible 14.9% ccupant Latent Computer Based Modeling Load Distribution A Latent 37.4% Duct Heat Gain 1% Zone Conditioning 3.5% ccupant 4.1% Equipment Sensible Envelope 5% 4.1% 3.3% Supply Fan 18.8% Lighting 7.9% 14

15 Comparison of Hand Load Calculations & HAPv4.1 Model The results concluded by both analysis methods were not very close to one another, although the HAP analysis did result in a load calculated within tons of the actual equipment specified in the design of the. The differential between tons Load Calculation Method Comparison 276 Hand Calculations HAP Model 800 Act ual Equipment Hand Calculation AHU's 3 & 4 sqft / ton cfm / sqft HAP Model Approach AHU's 3 & 4 sqft / ton cfm / sqft the hand calculation and the HAP model is approximately tons. Most of this difference can be attributed to three discrepancies between the calculation methods. First, solar load is taken into consideration using the HAP program, specifically, using weather data from the area. Second, the outdoor air load is much greater (approx. 177 tons greater) in the HAP analysis. This can be attributed to using the specific weather data for the area, and higher supply air flow rates. This again is a result of the 100% outdoor air supply condition for this building. Finally, the addition of the supply fan load has contributed over 116 tons to the calculated load, approximately 19% of the load calculated using HAP. The sqft / ton results also varied greatly. The hand calculation resulted in a value around four times that of the HAP approach. The results 15

16 for cfm / sqft (total and ventilation) were identical due to the 100% A supply, so the value was listed only once for each calculation method, and represents both of the required fields. This was also an area of great discrepancy. The value obtained using the hand calculations is 40% that of the HAP value. This is also an effect of the three previously mentioned factors that affected the load value. Hand Annual Energy Usage Calculations verview of Procedures Used Hand calculation of the annual energy consumption of the has been performed using weather data for taken from BinMaker Plus software. Total ton-hours were determined using this data. The calculated ton-hours in conjunction with flow rate data from the design documents is then used in calculating the energy consumption rates of the chiller, pumps, cooling towers and supply/exhaust fans. The occupancy schedule for this building was determined to be 7am to 5pm for all months of the year. Applying this data to the cost per kwh provided by Boston Edison, annual operation cost is estimated. The following equations were used in this calculation: Centrifugal Chiller: Cooling Towers: Pumps: Supp. / Ex. Fans: kwh (max) =.55 x (ton-hrs).55 = max kw/ton for chiller kwh =.1 x (ton-hrs).10 = max kw/ton for cooling tower kwh =.745x (hr bin ) x ((flowrate gpm x P[ft.wg.]) / 3960xη)) 3960 &.745 = conversion factors, η = efficiency of pump kwh =.745x (hr bin ) x ((flowrate cfm x P[in.wg.]) / 6356xη)) 6356 &.745 = conversion factors, η = efficiency of fan 16

17 The electric rates provided by Boston Electric are as follows: Customer Charge Distribution Demand Charge Distribution Energy Charge Transmission Charge Transition Demand Charge Transition Energy Charge Demand Side Mangement Charge Renewables Charge Total Energy Charge Total Demand Charge $15.23/month $5.92/kW /kwh /kwh $0.67/kW /kwh /kwh /kwh $/kwh $6.59/kW Results and Conclusions The two methods used in this hand energy analysis calculation yielded fairly similar results. The simplified method (not using demand factors) resulted in an annual energy cost of $121,972.66, while the complex method resulted in a cost of $126, Basic results from the hand calculation can be located in the tables below. The total cost/area of the hand calculations comes out to be $1.66/sqft. A full, detailed analysis is available in Appendix: C. Annual Energy Consumption Analysis: All Values are in [kwh] Chiller Cooling Tower Pumps Fans Lights/Equip Total 197,490 35,907 61,168 1,067, ,548 2,151,193 17

18 Simplified Annual Energy Cost Analysis: Chiller Cooling Tower Pumps Fans Lights/Equip Total $11, $2, $3, $60, $44, $121, Complex Annual Energy Cost Analysis: Total $126, Hand Annual Energy Usage Distribution Lights/Equip. 37% Fans 49% Chiller 9% Pumps 3% Cooling Tower 2% 18

19 HAP Annual Energy Usage Calculations verview of Procedures and Values Used The computer based simulation of the annual energy cost using HAP is a continuation of the design load analysis completed earlier in this report. Electric rates are used from the hand energy analysis portion of this report. An energy analysis was not performed by the design engineers. The reason for this is due to a hold that was placed on the project. When the project was revived, the deadlines were tight, and there was not enough time to perform an accurate analysis. Results and Conclusions The following tables describe the basic results from the HAP analysis. A detailed report is available in Appendix: D. Chiller Cooling Tower Annual Energy Cost Analysis Pumps Fans Lights/Equip Total $15,946 $7,219 $4,624 $68,758 $77,602 $174,150 It can be shown from this table that using all the information provided in the mechanical drawings, as well as the information on utility rates, the HAP program has estimated the annual energy cost for the at $174,150. The largest contributing factors in this annual cost are the supply and exhaust fans along with the lighting and equipment costs. The total cost/area of the HAP analysis $2.29/sqft. 19

20 HAP Annual Energy Usage Distribution Lights/Equip. 45% Fans 49% Chiller 9% Pumps 3% Cooling Tower 4% Comparison of Hand Energy Calculations and HAPv4.1 Simulation The results gathered from the hand annual energy calculation and the HAP energy analysis differ by $47, This may be attributed to the higher level of detail given in the HAP analysis. However, both results show the same proportional distribution of annual cost to each system component as the chart below shows. $180, $160, $140, $120, $100, $80, $60, Hand Calculations HAP Simulation $40, $20, $0.00 Chiller Cooling Tow er Pumps Fans Lights / Equipment Total Annual Cost 20

21 Emissions With the energy use of the comes the pollutants associated with the power generation for the building. Using data from Electric Power Annual 1999, Vol. II, ctober 2000, the total pollutant generation due to the energy use of the Jaharis center was calculated. The following table shows the pollutants generated by each category of energy use along with the totals. Pollutant Chiller Energy Use Category [lbm of pollutant / year] Cooling Tower Pumps Fans Lights/Equip Total S x x x x x x 10 4 Nx 8.67 x x x x x x 10 3 C x x x x x x 10 6 Mechanical System Costs Detailed cost data for the is not yet available, as the project is still incomplete. Therefore specific costs for this project are taken from information Tufts University has released to the public. A contact at Tufts University has stated that these figures are an approximation, but are generally close to the final numbers. The first costs of the mechanical systems in the are approximately $3,173,400. This includes contracts awarded to both the mechanical contractor and plumbing contractors. Dividing by the 180,000 total square feet of the building, the initial mechanical costs are $17.63 per square foot. 21

22 Mechanical Equipment Serviceability Included in the proper design of mechanical equipment is allowing adequate space around the equipment for servicing. The design of the gives ample room in both the penthouse and the basement for equipment service. All four customdesigned air handlers have access doors to every chamber and allow adequate room for the removal and installation of equipment and filters within the air handlers. Equipment in the basement is sparsely laid out with adequate room around component for servicing. Below are a sketch of the air handler with the nearest columns included, and a sketch of the basement s equipment layout showing an average human s size. 22