10/3/2012
Extreme Home Makeover: going from HERS 364 to almost zero 7th Annual North American Passive House Conference Ɩ September 28, 2012
Currently under construction in Boston, MA
• 5,641HDD
• 678 CDD
• Climate Zone 5A (moist, cool)
1 10/3/2012
A traditional timber frame house…
…that needs lots of work.
More issues become apparent during the first winter
40 ACH@50 Pascal | HERS 364
2 10/3/2012
What to do? •Must: – Replace roofing and siding – Replace mechanical systems – how efficient? – Add insulation –how much? – Add air sealing –how tight?
• Maybe: – Replace existing windows
• Would be nice: – Expand into 3rd floor attic and add 500 sf – Improve interior room layout and flow – Add photovoltaic panels to roof to offset energy consumption
Other considerations
• House isn’t precious.
• Owner plans to own and occupy the house for long time.
• Owner wants to push the energy efficiency (and design) envelope.
• Money – Owner is a poor architect – Low purchase price relative to value allows for significant investment. – Project may qualify for (significant) incentives, rebates, and/or tax credit programs. More energy savings = more incentive money
3 10/3/2012
Possible Incentives • National Grid’s Deep Energy Retrofit Pilot – $55,000 base incentive base on size and # of units – $10,000 extra for Passive House Certification – Review and approval by Building Science Corporation – About 50 participants – Pilot ends this year – New program for 2013
• Mass Save incentives – ERV/HRVs ($500 each) – High efficiency boiler ($1,700) – Mini-splits ($500 each)
Passivhaus Institut’s EnerPHit Standard
• Specific Heating Demand ≤ 7.92 kBtu/ft2/yr [4.75 kBtu/ft2/yr]
• Specific Cooling Demand ≤ 7.92 kBtu/ft2/yr [4.75 kBtu/ft2/yr]
• Total Primary Energy Demand ≤ 38 kBtu/ft2/yr
• Airtightness Criteria ≤ 1.0 ACH@50 [≤ 0.6 ACH@50 ]
Note: New construction Passive House threshold noted in [brackets].
4 10/3/2012
PHPP Pre-Certification Results
Envelope R-Values . Roof: Up to R-66 (5” polyisocyanurate rigid foam on exterior and blown-in cellulose in cavities)
. Walls: Up to R-54 (5” of polyisocyanurate rigid foam on exterior and blown-in cellulose in cavities)
. Conditioned crawl space walls: R-32 ( 5” closed cell spray foam, open cell spray foam at sill beam)
. Conditioned crawl space floor: R-13 ( 2" of XPS under a new concrete topping)
5 10/3/2012
Components . Windows: 0.13 u-value Schϋco ThermoPlus, removable Termoscreen T-2 sun for sun shading
. Doors: R-6.5 Makrowin 88 (front door); Schϋco ThermoPlus entry doors with side light
. Air Sealing: SIGA Majvest, Corvum tape, Wigluv tape
Mechanical Systems . HVAC: baseboard radiators (lower unit only) and air-to-air mini-splits
. DWH: Solar Thermal (Wagner Combi system) with Condensing Boiler (AFUE 96) backup
. Ventilation: Balanced ventilation with ≥ 93% (PHPP 84%) efficient ERVs in each unit (Zehnder ComfoAir)
6 10/3/2012
Standards and Code Comparison
Passive House EnerPHit Prescriptive Standards 8th Edition Massachusetts Building Code
Building Science ENERGYSTAR for Corp/ National Grid Homes Base Code (IECC Stretch Code: Stretch Code: Catbird Design (PHPP) DER Pilot (IECC 2009) 2009) New Construction Renovations Roof 66 60 38 38 Walls 54 40 20 20 Foundation: above grade 32 40 10 10 Foundation: below Grade 32 20 10 10 Slab 13 10 30 30 Windows 0.13 0.20 0.30 0.35 1 ACH@50 7 (testing Air Sealing (564 CFM@50) 660 CFM@50 4 optional) 7 ≤ 75 (alternate HERS without PV 27 ‐ 43 compliance path) ≤ 70 ≤ 85 PHPP Specific Space ≤ 20 (alternate Heat Demand ≤ 7.75 5.54 compliance path)
Easy decisions • Participate in National Grid’s DER Pilot
• Use Joe’s exterior wall detail: 4” cellulose in existing cavity + 5” Polyiso on the outside
• Contractor selection
7 10/3/2012
And some hard decisions • Selecting an energy efficiency goal and project scope
• Basement in/out of envelope, head height issues and more
• Window/door selection and install detail
• Solar thermal or less complex mechanicals?
• HRV vs. ERV?
• How much tape to use?
Basement and First Floor Plans
8 10/3/2012
Longitudinal Section
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Challenges • The PHPP / THERM learning curve, plus other calculations
• There are lots of opinions, but not always definitive answers on the cutting edge – re-circulating hoods, tape, ERV/HRV
• Existing buildings are a pain
• And sometimes structural engineers are too
• Expect the unexpected
REM Analysis
Roslindale Roslindale Catbird House Roslindale DER_PHPP DER_PHPP REM Analysis Results DER_PHPP w/SDHW w/SDHW & PV Design Loads (kBtu/hr) Heating 12.0 12.0 12.0 Cooling 17.6 17.6 17.6 Annual Loads (MMBtu/yr) Heating 12.9 12.9 12.9 Cooling 23.8 23.8 23.8 Water Heating 19.8 2.7 2.7 Annual Consumption (MMBtu/yr) Heating 13.5 13.5 13.5 Cooling 5.8 5.8 5.8 Water Heating 20.6 2.8 2.8 Lighting and Appliances 29.9 29.9 29.9 Photovoltaics 0.0 0.0 ‐26.7 Total 69.7 52.0 25.2 SDHW Profile 0 sf, 0 gal 112 sf, 184 gal 112 sf, 184 gal PV Profile 0 kW 0 kW 6.0 kW HERS Index 42 37 10 Kat adjusted HERS Index (‐10) 32 27 0
12 10/3/2012
Important Numeric Results and Predictions
HERS 364 | 650 gallons oil HERS 27-43 | 50 gallons oil
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