How to Build High-Performance Homes for Less Than $150/Square Foot Matt Sargent, Senior Energy Consultant Efficiency Vermont Nate Hayward, Principal Hayward Design Build Better Buildings by Design February 4, 2016 1
EVT HPH Envelope Specifications Component EVT HPH Specifications Foundation Wall R-30 Slab edge R-30 Under Slab R-30 Exposed Footing R-8 Exposed Floor R-40 Above Grade Wall R-40 Ceiling R-60 Installation Grade Grade 1, visual inspection mandatory Windows U-0.21 Doors U-0.25 Infiltration < 1.0 ACH50 2
EVT HPH Mechanical Specifications Component EVT HPH Specifications Heating/Cooling Energy Star with Boiler AFUE > 94% Ventilation ASHRAE 62.2 or PH, >80% SRE Hot Water Energy Star Drain Water Heat Recovery recommended Appliances Energy Star certified Lighting 95% Energy Star bulbs or fixtures 3
$4,783 $4,190 $3,904 $593 savings $879 savings $1,739 $3,044 savings 4
Each bin is approximately 1/3 cord. We used one full bin and a partial bin for the 2013/14 heating season the mini split was never powered up. - Chris Pike, Homeowner 5
What s included in $/SF Garage.What s not included.. Permitting Utilities Driveway Well Septic System Landscaping Outbuildings Pool/Spa Bonus Room above Garage 6
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Stephen Winters Associates, July 2011 Building assumptions: 1612 sf above-grade, 2 stories Full, semi-conditioned basement Flat attic South facing 3 bedrooms, 2.5 baths Full report available at: https://www.efficiencyvermont.com/about-us/white- Papers/whitepapers/2015/03/12/net-zero-energy-feasibilitystudy 8
Stephen Winters Associates, July, 2011 Envelope Building component Code HPH Added cost Notes Windows Double-glazed, U=0.32 Triple-glazed, U=0.20 Code: Anderson 400 series $6,792 SHGC=0.35 all SHGC=0.50 south, 0.35 other HPH: Triple-glazed Integrity (Alpine on south wall) Air/vapor barrier 800 cfm (approx. 0.5 160 cfm (approx 0.1 cfm50/sf AG Tescon Vana tape and installation at $672, plus $1500 for $2,172 cfm50/sf AG surface area) surface area) additional air sealing Basement walls R-15 Basement slab none Basement slab edge none Basement walls R-20 Basement slab R-20 Basement slab edge R-20 $6,176 Huntington Homes cost: Under slab insulation actual for R-15 $2426, Foundation ICF R-21 $3750) Rim insulation R-21 Rim insulation R-42 $696 $25,724 Insulation Walls R-25 Walls R-40 $8,064 Added 1" rigid foam to exterior above Huntington Homes estimate to comply with 2015 code, subtracted $0.90/sf material as it's now required by code. Inside foil faced rigid on inside (R-20 was Huntington Homes code wall) Attic R-49 Attic R-60 $1,824 Actual in Huntington Homes Net Zero building was R-70 Mechanicals Ventilation DHW HVAC 100 cfm, exhaust only (#bed+1)*25 cfm From boiler Propane 85% sealed combustion boiler 100 cfm, HRV (#bed+1)*25 cfm Air source heat pump, annual COP 1.5 Air source heat pump, annual COP 2.3 $3,800 Panasonic fans w/timer vs. LUNOS and Panasonic Used ducted Venmar for HPH w/approx same cost Code: Huntington Homes used propane Triange Tube $2,600 $500 Boiler and a State Hybrid REEM; DHW net COP considers supplemental heat supplied by ASHP ($5,900) HPH: Replaced propane Triangle Tube 95% AFUE Boiler ($10800) with Mitsubishi MSZFE/MUZFE ($4900) ASHP Totals $26,224 9
South Burlington HPH upgrade 2015 Building assumptions: 1697 SF Sloped and flat ceilings 2 stories Full basement, semi -conditioned 3 bedrooms, 2.5 baths 10
South Burlington HPH upgrade, 2015 Building component Code HPH Code cost* (optional) HPH cost* (optional) Added cost* Notes Windows Double-glazed, U=0.25 SHGC=0.35 all Triple-glazed, U=0.19 SHGC=0.50 south, 0.35 other $ 5,400 $ 6,780 1,380 Code JeldWen Single hung, HPH Orion Double Hung Envelope Mechanical Air/vapor barrier 1,725 Additional air sealing, intello membrane at slope ceilings Framing 3,450 Budget at this time Window/Door Trim 500 Jamb & Sill extensions $27,935 Basement walls R-15 Basement walls R-30 Basement slab none Basement slab edge none Basement slab R-20 Basement slab edge R-20 $ 3,250 $ 11,600 8,350 Insulation Rim insulation R-21 Rim insulation R-42 Walls R-21 cavity with R-6 Double stud walls R-40 Zip Sheathing dense pack 6,550 Attic R-60 Attic R-60 Ventilation Exhaust fans at bathrooms TBD 4,600 Budget at this time DHW TBD HVAC Gas Furnace 95.5% efficient w/ecm Electrical 1,380 Budget at this time Totals $27,935 s 11
Revised EVT HPH Ventilation Brand Name Model Number HRV/ ERV SRE @ 32F Test Air Flow @ 32F SRE @ -13F Fan Efficacy @32F (cfm/w) Broan HRV150 TE HRV 75 49 64 2.0 Lifebreath 195ECM HRV 81 64 69 1.9 vanee (Venmar) HRV90H VECM HRV 75 49 64 2.0 Venmar E15ECM HRV HRV 75 49 64 2.0 12
HPH Specification Revision for Windows Original Spec U 0.19 Revised Spec U 0.21 13
HPH Specification Revision for Slab insulation Existing Spec = R-30 Revised Spec: R-30 Foundation Walls R-20 Below Grade Unheated Slab and Slab Edge R-30 On Grade or Heated Slab and Slab Edge 14
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HPH Air Leakage Spec = 1.0 ACH50 Design with complex construction details makes this target difficult to reach 18
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HPH Specification Revision for Hot Water Existing Specification = Energy Star Energy Factor (electric) 55 gallons EF 2.0 > 55 gallons EF 2.20 Revised HPH Specification Well insulated, high efficiency electric hot water tank Low flow/epa Water Sense fixtures Drain water heat recovery system installed at least for master bath shower, whole house preferable Low stored-water-volume or demand re-circulator (see Water Sense requirement below) An efficient hot water delivery system that stores no more than.5 gallons of water between the source of hot water (the water heater or a recirculation loop) and the furthest fixture in the home. Recirculation systems must be demand initiated (push button or motion sensor activated) 20
HPH Specification Revision Flat Ceilings Original Spec = R-80 Revised Spec = R-60 Example: 1300 sf flat attic at R-60 = 4.1mmBtu/yr 1300 sf flat attic at R-80 = 3.1 mmbtu/yr additional energy use = 1.0 mmbtu/yr About $18/yr if using heat pump at COP 2.5 21
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The big question: How can we deliver high performance homes at a price point that is affordable to the general population, not just the select few? 24
The Design Team: Homeowner, Architect / designer, Energy consultant, Engineer, Builder / G.C., Subcontractors. 25
Design principles: Keep it simple, Invest in the envelope (air tightness, and high R-value), Keep mechanicals simple, South orientation, Broad side facing South, roof ridge running East to West to accommodate roof mounted PV, +/- 7% of finished floor area in South glazing high SHGC, Minimize other windows to the extent aesthetically possible, Keep bedrooms and living areas along the south side, Open floor plan. 26
South Elevation North Elevation East Elevation West Elevation 27
Site Plan Perfect South orientation 28
Floor plans Total 1,908 finished SF 1 st floor 29
Floor plans Total 1,908 finished SF 2 nd floor 30
Super-insulated Slab on grade, with radiant heat 31
Insulation/slab subgrade with high density XPS for bearing pads. 32
Two staggered layers of EPS insulation totaling R-30 sub-slab. Radiant slab for finished floor. 33
R-30 XPS slab edge insulation. Falls under the middle of the double stud wall. 34
Poured 5 slab with trowel finish 35
Diamond grinding the slab for a sands finish with some exposed aggregate 36
Cost effective, bullet proof, modern, finished floor option. Close up of exposed aggregate after first pass of diamond grinding 37
Double stud wall (both 2 x 4 ). Exterior load-bearing, interior non load-bearing. Total cavity depth = 12 38
Critical air sealing detail foundation wall to sheathing 39
Continuing the air sealing (high performance tape on Zip sheathing) 40
Top floor top plate connects double stud wall and extends inward 41
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After the trusses are on, and the roof is shingled, osb sheathing is applied to the bottom cord of trusses and taped BEFORE the interior partitions are built. This completes the primary air barrier 43
Energy heel on roof trusses, with extended overhangs, and an incorporated walkway to better facilitate loose fill cellulose and air sealing. Walkway 18 energy heel 24 horizontal eaves for passive solar shading 44
Incorporated walkway in truss to better facilitate loose fill cellulose installation and air sealing. 45
Attic air sealing 46
Louvered vent / door for attic ventilation and access. 47
Windows: Earthwise Orion -Triple glazed, -Casement outswing, double hung, fixed, and awning. -Built by PVC Industries in Clifton Park NY, -U-factors from 0.19-0.21 +/-, -Selective coatings allow you to specify higher solar heat gain coefficient on South windows, -Very cost effective, $25.37 per square foot of RO (for this specific window order). 48
Simple sheetrock returns and 5/4 Maple sills Incorporate 4 flat casing with j-channel to receive siding 49
Blower door testing, shell only. After all mechanicals are roughed in, but before insulation and drywall 230 CFM (230CFM x 60 minutes = 13,800 cubic feet per hour) House total conditioned volume = 16,428 cubic feet 13,800 / 16,428 = 0.84 ACH 50 shell only 50
Pressurized smoke testing for any air sealing deficiencies 51
Net and dense packing with cellulose 52
Readout on dehumidifier no other heat in use, outdoor temp 10 F After insulating, we plugged in a dehumidifier The dehumidifier alone was enough to overheat the house, so the boiler/radiant slab did not run when the dehumidifier was in use. 53
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Mechanicals Heating and on-demand hot water with Bosch condensing modulating natural gas boiler. Three zones: 1. Domestic hot water 2. Radiant 1 st floor slab with slab sensor t-stat 3. 2 nd floor high temp baseboard 55
Why natural gas heat? 56
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Mechanicals - LUNOS e2 Ductless, simple, and highly efficient heat recovery ventilation (HRV) system Heat recovery efficiency: 90.6% 1. No plumbing / HVAC labor needed 2. Fast to install 4. Total materials cost for one house $2,941.62 58
From foursevenfive.com blog LUNOS e2 sizing recommendations 59
Current photo expected to be complete except finish site work by March 1 st. Call me if you want a tour when it is done. 802-578-3078 60
Costs to upgrade from EV Certified to High Performance Home 61
So what does this all cost? To create a level playing field and allow cost comparison with differing site specific costs I am excluding from the cost per square foot: Water source (well, or municipal hook-up), Septic or sewer, Power, phone, cable (other than an allowance for secondary service), Driveway beyond 60, Any permits, impact fees, allocation fees, Blasting, No import or export of fill, No imported top soil (assume it is all stockpiled on site and used at finish). 62
With the caveats on the prior slide this house is projected to cost: $135.40 per square foot. So, at 1908 finished/conditioned square feet that equates to $258,343.20 -included in this cost is an allowance for: general conditions/overhead and profit totaling 20% Total high performance home upgrades cost: $17,000.51 which equals 6.58% of the construction costs Kind of a no-brainer to go for the HPH upgrade! 63
If we switch the heating to air source heat pumps (2 mini-split heads) and use an efficient, well insulated, electric hot water heater that would drop construction costs by $5,100 to $253,243.20 ($132.75/square foot) It would also drop the high performance home upgrade cost by the same $5,100 to $11,900.51 In this scenario, the total high performance home upgrades represent ($11,900.51 / $253,243.20) = 4.70%. 64
A few nice to have items that ARE included in these costs: Upgraded kitchen cabinets with honed granite countertops, Central Vac, Attached 2-car garage (with 40 amp outlet for potential EV charging), Attic trusses above garage for cold storage and potential future finished area (accessed via insulated door in second floor hallway), 65
Garage attic trusses 66
Lessons learned how I plan to tweak design and specs moving forward- -Use more efficient exterior dimensions (i.e. increments of 4 or 8 ), -Do a better job of consolidating the plumbing fixtures. Reducing the hot water delivery time and volume, -We love the polished concrete floors, but the lack of a basement may reduce the pool of buyers, 67
Is a natural gas boiler & radiant slab a good choice for a high performance home? Pros: Cons: -Nice aesthetic (no visible heat source like a mini-split wall cassette), -Great dry heat during construction, -Nice to have the integrated on-demand hot water, -Natural gas is the least expensive fuel source at $15.04/MMBtu (as of Jan. 2016). -Fully distributed heating reduces the temp delta that point source heat has. -Much more efficient domestic hot water vs. ASHP hot water heater with net COP = 1.5 -Cannot provide air conditioning, -When the heat load is very small the slab temp is only a few degrees above room air temp, so it will not feel warm on bare feet, -Boiler, zone valves, circulator pumps, radiant tubing and labor is certainly more expensive than a couple of mini-split heads, -Potential solar gain in a heated charged slab could cause overheating (blinds would limit that), -You can t be site net zero burning fossil fuels. (Can t offset NG with PV). 68
Mechanically, on our next high performance home we would like to try: Heating: One mini-split air source heat pump per floor, with 2 nd floor t-stat in master bedroom (keep the boss happy), Hot water: We would like to try a small on-demand electric hot water heater and Manabloc distribution with 3/8 home run supplies in a tight/stacked plumbing fixture plan. This would be very cost effective and all electric. We don t like heat pump hot water heaters in small homes with no basement (noise and parasitic effect on heating system). HRV: LUNOS e2 Invest in the envelope, keep mechanicals as simple as possible! 69
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