With the cold weather come thoughts about our energy bills and thermal comfort. If you’ve been dreaming of creating a cozy new home with tiny utility costs, here are our Top 10 recommendations for energy efficient building techniques, materials and systems.
1. Be a like lizard - Passive solar design is the least expensive way to cut down on energy bills and make your home more comfortable. It means harvesting the sun when it’s cold and blocking it out when it’s warm (like our cold-blooded reptilian friends). You place the majority of your windows on the south side (where it’s easiest and most important to control when and how the sun enters the house. Eliminate skylights, reduce the windows on the east and west, protect the west side with a very deep cover, and minimize the windows in the north. Additionally, your architect can size the overhangs to only admit sun when it’s beneficial, and select window films to limit or welcome UV radiation depending on their orientation (“tuning” the windows). Lastly, the more thermal mass (big heavy stuff, like stone, water, concrete, tile or earth) that you have inside the envelope of the house, the longer it takes to heat up and cool down. This thermal mass absorbs solar radiation and can help a house coast through cold nights and warm days.
2. A puffy coat - Foam insulation – It’s hard to have too much insulation (although the return on investment decreases as you get to the upper limits). Foam is the best per inch (the R-value), and provides excellent air-sealing, but is also the most expensive. You can get either closed-celled or open foam blown into wall cavities, adhered to roof sheathing, floor framing and crawlspace walls. Closed-celled is the best insulating and is more expensive. We typically also wrap a 1” XPS rigid insulation board around the entire house to prevent “thermal bridging” through the structure. Cellulose is a good cost-effective option that uses a recycled material and fills in all the nooks and crannies. Blown-in-bib fiberglass is about the same cost and effectiveness. Fiberglass batts are the cheapest and least effective.
Recommended insulation: R-50 to R-60 - ceiling | R-21 to R-30 - walls, soffits, rim joist | R-10 - under-slab
3. A hippy puffy coat – Strawbale has been around for 130 years in Colorado and it still works. It’s one of the greenest, lowest carbon methods you can build with. Walls are fat, romantic and wobbly, and they have and R-50 insulation value and a high thermal mass. A strawbale house actually costs the same or more than a conventional house (because it requires all the subcontractors to do custom work), but if you like getting your hands dirty, you can have fun putting up your own super-energy-efficient walls.
4. Catch the sun – Solar panels – Panels are getting more and more efficient every year, and their overall cost is still subsidized about 50% through a combination of rebates and tax credits. (PS- if you’re waiting for Tesla’s sexy solar shingles which they claim cost no more than a conventional roof shingle, don’t hold your breath – it will probably be a couple more years, and they will likely cost a lot more). Consider sizing your solar system to include electric vehicle charging and install 240v outlets in your garage to accommodate future charging needs. According to the Colorado Energy Office, by 2030 Colorado could have close to one million EVs on the road.
5. Trap the sun – Windows are generally the weakest spot in the envelope of a house and typically comprise 10-25 percent of the surface area. Think of it like walking around on a freezing day in a thick down jacket (your walls and roof) but with the zipper open. These days, double paned Low-E, Energy Star rated windows with a U-value (thermal transmittance rating) of 0.3 or lower are the norm in Boulder County, but if you want to create a Net-Zero Energy home or are building at higher elevations, then gas-filled, triple paned windows with a double low-E coating can stay warm to the touch even when it is zero degrees outside. (Check out locally made Alpen windows www.thinkalpen.com). Additionally, your architect can consider using low-E films to “tune” the Solar Heat Gain Co-efficient which determines how much UV each window admits.
9. Conventionally awesome – Super-efficient conventional furnaces, boilers and evaporative coolers have improved dramatically in the last decade. Newer sealed combustion furnaces can get up to about 95% efficient. Boilers 98%. However, even the most efficient AC (SEER 21) still is one of the biggest energy hogs in a house; fortunately, there is a simple old-fashioned device, evaporative (aka “swamp”) coolers, that are less expensive and ~70% more energy-efficient to run. The main downside to Evap coolers is that they can’t be ducted around the house so they have to just dump into one central section – to move the cool air around you have to open doors and windows to pull the air into that area.
10. LED Lights – The price of LED lights has been plummeting for the last decade. Equally importantly, the quality of the light produced continues to improve. The color spectrum on can now very close to incandescent bulbs (2700K), but they last 10 times as long and use ~90% less energy.
On top of all that green goodness, you get some greenbacks back too. Here are some places to look for rebates, Tax Credits, and various financial incentives:
· www.energysmartyes.com - a clearinghouse of Boulder County programs & rebates
· https://www.xcelenergy.com/programs_and_rebates
· www.cleanenergycu.org - Low cost Credit union loans for solar and Electric vehicles
· https://www.irs.gov/newsroom/energy-efficient-home-improvements-can-lower-your-taxes
And here are some top spots to go for local info and professional help:.
· www.CGBG.org - a collection of local green building professionals
· https://bouldercolorado.gov/plan-develop/energy-conservation-codes
· https://www.bouldercounty.org/property-and-land/land-use/building/buildsmart/
About the author:
Scott Rodwin, AIA, LEED AP is the owner of the Rodwin Architecture + Skycastle Construction, a 13 person award-winning design/build firm specializing in high-end custom green homes in the Front Range. [email protected] www.rodwinarch.com