or just a great HERS / ERI score.
It’s not easy to show energy code compliance in climate zones 6 and 7. Especially if you’re working in a jurisdiction that has adopted above-code requirements. Designers here’s an exercise to help get your design on its way to IECC compliance and beyond. On your next project, before starting your typical design process, rough out a schematic design, but forget all clients wishes, ARC guidelines, height limits, etc. and design for energy conservation by substituting the following parameters…
- Make the thermal envelope a simple, regular volume.
- Share assemblies with other structures, when possible, but make that party assembly very airtight.
- Follow the prescriptive code for air barriers and insulation levels.
- Maximum 20% glazing; 20-30% glazing; plan for really, really good windows, over 30% plan for great triple-pane windows.
- Put as much of the insulation on the outside of the assembly as you can, or frame with Efficient Framing techniques or use alternate techniques that reduce thermal bridging like; ICFs, SIPs, Larson trusses, adobe, strawbale, etc.
- Make the roof within 20° of optimal pitch (10:12 to 14:12) and orientation (160°-200° south) for solar, free from obstructions and penetrations.
- Use passive solar heating techniques when possible; insolation managed by proper overhangs and low-e coatings on glazing.
- Plan for no gas or propane, all electric house.
- Use no snowmelt.
- Locate the mechanical room, in the core of the house, minimize distribution runs. Give plenty of room to equipment for service. Easy access; no hatches, ladders or crawling.
- Locate the outdoor side of the heat pump equipment. Protected from snow and ice.
- Don’t use site-built forced-air ductwork if you can avoid it. Radiant or ductless preferred. If not, don’t combine ductwork with garages, ventilated attics or ventilated crawl spaces. Insulate it and seal it very well.
- Plan for a stand-alone occupant ventilation system, with occupant controls and easy access for filter cleaning; not in a crawlspace or attic. Ducting this is okay.
- Heating; use GSHP (ground source heat pump) if you can. If not, use ASHP (air source heat pump) and passive heating techniques.
- Cooling; skip it altogether if you can. If not, use ASHP, evaporative and passive cooling techniques.
- Hot water; use thermal solar per-heat if you can. If not, use HPWH (heat pump water heater). Ducting this is okay.
- Use no heat tape.
- Use ENERGY STAR appliances. Keep refrigeration loads as low as possible. Induction range and convection oven.
- Plan for low flow plumbing fixtures and fully insulated lines.
- Plan for DWHR (drain water heat recovery)
- If hot water runs are still long enough to require recirculation, use a smart pump with occupant sensors in the bathrooms and a temperature sensor to control the pump runtimes.
- Maximize the PV array size.
Designers: Now you have a schematic design optimized for potential energy conservation. As you move on to your typical design process, keep this design in the background. Know that the more your design develops away from the energy conservation architype, the harder it may be to reach specific performance goals.
Note to Structural Engineers: Your challenge is to help the Architects keep as much steel and wood out of the thermal envelope as possible. Support several inches of Continuous Insulation, even behind stone veneer. Keep the foundation completely covered in insulation, even at patios, doors and behind stone veneer.
Note to Mechanical Engineers: Your challenge is to help the Architects reduce all equipment loads, reduce runs and maximize efficiency. Investigate new technology and equipment and learn how to work with it. And help us all reduce a house’s dependence on gas.