Passive House The Road to Net-Zero
Net-Zero into the Future Net-Zero defined as producing as much energy onsite as the building uses annually. Using net-metering with the grid, so grid is acting as 100% efficient battery Utilities are currently willing to use residential-scale renewables to offset fossil-fuel use As renewables increase as % of total electricity mix, utilities will be challenged to manage the grid Electricity storage is critical for long-term integration of renewables at the utility scale; PH can help this by using housing as a thermal battery. Time-of-use may become more common, net-metering less common
The Demand on the Grid
How much site energy for 2000SF home? Code Built: 55 panels PH: 25 panels Roof space is a limiting factor on road to net-zero!!
Energy Conservation vs Renewables Credit: Wall Street Journal, 04/08/09
Simplicity of Passive House Costs Envelope Performance Passive House energy requirement is so low it doesn t require a conventional heating system Typically, space heaters are installed to meet peak heat load required This solution is VERY user friendly Savings on central heating system helps cover additional construction costs Passive House standard typically adds 5-10% to the budget It is more cost effective to save energy than to generate it with sustainable systems
Passive House Targets
Passive House: The Old Standard Thermal Performance of Envelope Total Energy Consumption 15 kwh/m 2 120 kwh/m 2 Airtightness 0.6 ACH @ 50 Pa Passive House E-Design
Challenges with one target fits all Annual Heat/Cooling Demand Huge range of climate zones in North America. NS has longer winters, more HDD, and more solar radiation Annual Heat Demand does not ensure comfort NS requires a tiny cooling demand. Based on German TFA. Passive House E-Design
Passive House: Climate Adjusted Standard Thermal Performance of Envelope Total Energy Consumption varies by climate ( 7.1KBTU/sqft/yr in NS) 6000 kwh/person/yr Airtightness + 0.05 cfm/sqft @ 50 Pa Passive House E-Design
Total Annual Source Energy Consumption Total Energy Consumption Credit: EPA
Climate Adjusted Standard: Total Primary Energy Higher plug loads mean more internal gains, but also higher baseline total energy Less efficient grid, so higher source energy factor to calculate electricity PE =3.1 Normalized by # people, not area Occupancy based on # bedrooms + 1 Encourages small houses with more density Domestic hot water as important to PE as heat demand Allowed to count PV to offset PE Convert to site energy 6000/3.1 = 1936 kwh/person/year
Passive House Tools and Verification
Energy Modelling - PHPP
Energy Modelling WUFI Passive
Envelope Details - THERM Thermal Bridge Free Construction Credit: Gregory Duncan Architect
Solar Assessment: Solar Pathfinder
Air Leakage Testing Blower Door, Duct Blaster, Smoke Machine, Thermal Imaging Camera
Ventilation Commissioning Balance unit supply and exhaust Insure air flow to each space is operating as per the design. Check the unit is operating at the right electrical use.
Passive House Concept
Passive Solar Homes NOT PH
Passive House Energy Flow Code Built Heating Gains and Losses Passive House Built Heating Gains and Losses Solutions 22
Passive House Approach World s leading energy efficiency standard Key principles: - Passive design - Super insulate - Eliminate thermal bridging - Very air-tight envelope - High performance windows and doors - High efficiency mechanical and electrical systems. 23
~50% of energy efficiencies are achieved by smart design ~50% are achieved with what we put in the building 24
Principles of Design: Size The best thing you can do to be environmentally responsible is design the smallest possible space that meets your program increase density!!! 25
Principles of Design: Shape Design for compact building shape Add architectural interest with unheated spaces Keep an eye on Surface Area of Building Envelope to Volume ratio Easier in bigger buildings 26
Passive Design Site Considerations Orientation to grid north Shading from other buildings Shading from building reveals Shading from trees Exposure to prevailing winds summer and winter 27
Solar Orientation Use the energy modelling tool to optimize passive design East glazing morning light, small net-energy gain, doesn t contribute to overheating South glazing daylight all day, good netenergy gain, watch for overheating in Aug-Oct West glazing evening light, small net energy gain, major overheating difficult to shade North glazing filtered light, large net-energy loss, minimal overheating 28
Project Glazing Design Strategies Limit glazing to the north, maximize glazing to the south Spec casement, awning and fixed vinyl windows with triple glazed, low e, argon filled Design shading to reduce overheating 29
Continuous, High R-value Insulation Assemblies Use the energy modelling tool to optimize insulation levels Use thick insulation layers Eliminate thermal bridging in assemblies Consider other environmental impacts of materials Keep on eye on building science 30
So What Does It Take? Passive House Standard in Atlantic Canada Walls R50 + Ceiling R100 + Under foundation R35+ Triple glaze windows Passive Solar Design 3 times more air tight than R2000
Design Principle: Air Tightness Reduce air leaks by 10 x Air leakage accounts for up to 50% of heat loss in buildings. Credit: Burkhard Schulze Darup 32
Benefits of Air Tight Construction Reduce heat loss by up to 50% Air moves water = moisture in assemblies = mold and rot issues Air tight = durability = minimal maintenance COMFORT: - Fewer drafts - Easier to maintain temperature - Quieter - Better indoor air quality 33
Principles of Design: Mechanical Design Strategies before Engineering: Small point source heating system High efficiency HRV Efficient hot water design 34
Heating: Electric Options Geothermal Electric Thermal Storage (ETS) and electric baseboards Baseboards Radiant In-floor The winner: Ductless mini heat pump
Heating: Non-Electric Options Wood Biomass Key is to find a unit with a small heat output
Domestic Hot Water Heater options Electric storage Solar thermal hot water The winner: Heat pump hot water heater (Measured COP of ~2-3)
Mechanical Ventilation High Efficiency HRV or ERV HRV ( Heat Recovery Ventilator) Max efficiency: LifeBreath 195 EMC at 82% ERV (Energy Recovery Ventilator) Max efficiency: Zehnder up to 92% Watch the electrical efficiency as well as the heat recovery efficiency
Lighting & Plug Loads Responsible for 20% of residential energy consumption Up to 50-70% of consumption in high performance houses Energy Use by End- Use (PJ) 1990 1999 2009 Total Growth 1990-2009 Lighting 51.4 56.4 60.6 17.8% Other Appliances 29.4 44.3 75.9 158.3% Credit: NRCan
Lighting & Plug Loads Homeowner education & engagement matters Credit: Building America
Lighting & Plug Loads What s using all the electricity? Computer (~25 W Standby) Television (ENERGY STAR 37 LCD 149 W On, 1 W Standby) VCR/DVD (17W On, 7 W Standby) Cable Box, HDTV DVR (35 W On, 25 W Standby) Stereo (65 W On, 2 W Standby) CD Player (10 W On, 2 W Standby)
From Passive House to Net-Zero Reduce heat load, use heat pump with electric baseboard backup Reduce hot water load, use hot water heat pump or solar thermal Reduce ventilation load with high efficiency HRV/ERV and efficient ECM fans - Commission to design flow Reduce appliance electrical use with most efficient models Reduce lighting load with LEDs Educate home owner on plug loads, reduce standby loads Install renewables to meet site energy
Renewable Options for PH Geothermal: Generally too expensive for the loads sizes in a Passive House. Solar thermal: Good for multifamily buildings. Difficult operationally for single family. Maintenance is required. Wind: Not cost effective at a small scale. Issues with turbulence and roof mounting. PV: Need roof space, very low maintenance, simple to operate, pricing continues to drop.
Net-Zero Ready / Certified Passive House
Net-Zero Ready Specs: Roof area accommodates required number of panels Trusses engineered for panels Electrical Panel sized for PV circuits Conduit from electrical panel to roof Wired from panel to disconnect by meter 45
Net-Zero Energy Calculations Total Site Energy (kwh/yr) 8531 Panel Size (W) 295 Annual Energy Produced per Panel per Year(kWh/yr): 338 Panels Required for NZE: 25 Cost of Solar PV installed: $17,000 Annual energy savings: $1,731 10 Year ROI at today s electrical rates Panel Layout on Roof 46
Modern Lake Front 50% of energy use generated with PV
Murray Pastures 25% Energy from PV
Olive Urban Retreat: Net Zero Ready
Further Information NATALIE LEONARD, P.ENG natalie@passivedesign.ca www.passivedesign.ca Passive Design and cannot be redistributed or used without consent. 50