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These houses at Jenny Way on Martha's Vineyard range in size from 1,080 to 1,400 square feet. Designed and built by South Mountain Company, these were the first LEED Platinum, single-family, affordable housing units in the country. Photo: Randi Baird. Click on image to enlarge.

Number 5 in my list of the top-10 green building priorities is to build smaller houses and optimize the use of materials.

While the trend has begun to turn around, we've been building larger and larger houses for decades. In 1950, the average house in the U.S. was about 1,100 square feet, while there were about 3.4 people per household, according data I compiled for a 1999 article in Environmental Building News. The U.S. Census Bureau reports that in 2009 the average new house in the U.S. was 2,438 square feet (down slightly from 2,518 square feet in 2008), while the average household size was 2.6 people. In the past sixty years, house size has increased 120%, while family size has dropped 24%, so square footage per family member has nearly tripled (from 324 to 938 square feet).

From an environmental and energy standpoint, building smaller houses is a winner. Smaller houses take less material to build and they use less energy to heat and cool. This is common sense, but it's amazing how rarely people think about it. For the same EBN article referenced above ("Small is Beautiful: House Size, Resource Use, and the Environment"), we ran some numbers comparing the annual energy use of two homes in Boston: a reasonably well-insulated, 3,000 square-foot house (R-19 walls, R-30 ceilings, double-glazed low-e windows); and a poorly insulated, 1,500 square-foot house (R-13 walls, R-19 ceilings, double-glazed non-low-e windows). Based on energy modeling by Andy Shapiro of Energy Balance, Inc., heating and cooling costs for the poorly insulated, compact house totaled $421 per year, while heating and cooling the reasonably well-insulated, large house totaled $635.

The larger house is more energy-efficient (it might even meet the standards for green home certification), but its total energy use is 50% greater than that of the smaller house. This isn't meant to suggest that we shouldn't insulate our houses well if they're small, but rather to illustrate just how significant size is to the energy consumption of a house.

Very significantly, the smaller house will also likely cost less to build--even if higher quality, more expensive materials are used. When I hear that green homes cost more than standard homes, my first response is always to point out that smaller homes are much greener--and those homes usually cost less, not more.

Interior of one of the Jenny Way homes, which provide a spacious feel despite the compact design. Photo: Randi Baird. Click on image to enlarge.


Be aware that creating successful compact houses isn't only a matter of shrinking the dimensions. Designing small homes that feel spacious and are comfortable requires a skilled architect or designer. Expect to spend more for a design that minimizes square footage yet feels spacious and comfortable. The investment in design will be paid back during construction--and lower operating costs.

Optimizing the use of materials

In addition to building smaller, there are other ways we can save materials--and money--in building. A few of these strategies are listed below:

  • Use standard ceiling heights. Materials cost and cut-off waste can be reduced by building to the standard dimensions of studs and drywall.
  • Build on a standard two-foot or four-foot module size. House dimensions of 28 feet by 36 feet for example, will use about the same quantity of materials as a house that's 26-1/2 feet by 34-1/2 feet, because lumber and sheet goods come in multiples of two or four feet.
  • Use "advanced framing" techniques with wall and roof framing 24 inches on-center, single top-plates with rafters set exactly above studs, wall corners produced with three rather than four studs, and the elimination of unneeded framing at window and door openings. Not only will advanced framing techniques save materials, they will also improve energy performance, because there's less wood and wood doesn't insulate as well as insulation.

Both of these strategies--building smaller and optimizing materials use--save money during construction and reduce energy consumption. It's a win-win solution that's become all the more important in our highly constrained economy.

My top-10 list of green building priorities so far:

#5. Build smaller and optimize materials use
#6. Ensure durability and reuse existing buildings
#7. Protect and restore the site
#8. Use green materials
#9. Create resilient, climate-adapted buildings
#10. Make it easy for homeowners to be green

In addition to this Energy Solutions blog, Alex writes the weekly blog Alex's Cool Product of the Week, which profiles an interesting new green building product each week. You can sign up to receive notices of these blogs by e-mail--enter your e-mail address in the upper right corner of any blog page.

Alex is founder of BuildingGreen, LLC and executive editor of Environmental Building News. To keep up with his latest articles and musings, you can sign up for his Twitter feed.

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Comments

1 I'm not a professional, I'm a posted by Susan Assel on 11/14/2010 at 08:10 am

I'm not a professional, I'm a simple person wanting to build a small - very small house: 650 sq. ft or so. There are very few places I'm allowed to do that legally. I've been hunting for a place to build my small house and my only choice is to build out in the country, far from any major town or city, on a piece of land that's not part of a "subdivision". All the sites in subdivisions that I've looked at - even if the "subdivision" plan fell through and now the bank owns 34 of the planned 35 sites! - have covenants and restrictions that demand a house of 1,800 sq ft. or more. Besides the obvious energy demands of a house this big, how on earth can most people afford to build a house that size anymore? With the economy like it is and home ownership for so many in danger as it is, what is it going to take to convince people that "bigger is NOT better" now?

I'm very discouraged. It seems wrong that in this country, a person is not allowed to build a small, energy-efficient home in order to live simply and try to be as self-sufficient as possible.

2 I love Lloyd's suggestion tha posted by Alex Wilson on 10/23/2010 at 02:03 pm

I love Lloyd's suggestion that residential energy codes should be based on absolute energy consumption, rather than efficiency! How can we advance that idea? The same idea could be incorporated into voluntary residential green building programs--basing energy consumption targets on absolute consumption rather than efficiency. (The Vermont Builds Greener program comes the closest to this.) Yes, it will make it tougher for houses for large families to come in green, but maybe it's not such a bad thing to be rewarding smaller families!

3 Alex and Lloyd. It's a neat posted by Bill Swanson on 10/25/2010 at 06:47 am

Alex and Lloyd. It's a neat idea to base the housing energy code on total energy used. But how does it get implemented. If I build a huge house and show some math that the energy use will meet Code. What happens if my house uses double the estimate. Oops, my math was bad or my assumptions were bad. It would seem to encourage bad energy modeling. No one's going to tear down the house for failing to meet Code. An unenforcable Code is not effective. I like the idea. I just don't know to enforce it. Maybe predefine as many assumptions as possible so all of the energy models are as similar as possible.

4 "This isn't meant to suggest posted by Lloyd Alter on 10/20/2010 at 09:46 am

"This isn't meant to suggest that we shouldn't insulate our houses well if they're small, but rather to illustrate just how significant size is to the energy consumption of a house. "

Actually, I think we should change the required insulation with house size. We should be measuring absolute consumption rather than relative efficiency. As houses got larger the wall insulation got higher but got overwhelmed by the house size. I wrote earlier:

"Let's change our building codes to permit a specific amount of energy consumption, period. If you want to build a house twice as big as, say the design consumption of a 2000 footer, you have to double the insulation in the walls or cover the roof with photovoltaics. If you want a six burner professional stove, add some more insulation still.

This shouldn't affect the rich; they can afford the insulation. It will help the poor; small houses can probably have even lower levels of insulation than they do now. It may hurt the middle-of the road suburban McMansions, but they are dinosaurs anyways."

5 If you know anyone contemplat posted by Patti Southard on 10/20/2010 at 11:19 am

If you know anyone contemplating a remodel? Or maybe you’re thinking about some energy improvements before the cold weather settles in? King County actually has some great new online tools that offer practical advice on how to make smart remodeling choices that also help protect your family’s health and the health of the environment. Today, they launched the first episode of EcoCribz, the first edition is the home to the founder of Home Performance Washington; David Bangs. (link to: http://your.kingcounty.gov/solidwaste/greenbuilding/eco-remodel.asp), an online video series that takes a look at what local families are doing to make their remodels greener. The videos are designed to put a little fun into the decision making process, as well as share tips from the top green building pros in our area. King County also has an online tool called the Eco-Cool Remodel Tool (link to: www.ecocoolremodel.com), which allows you to click around a virtual house and get tips on how to green up your house inside and out. It addresses energy- and water-efficiency, indoor air quality, and helps you sort out the healthiest and sustainable material choices. The tool also links to a whole host of resources where you can dig deeper and find the people and products to make it happen. Check it out. If you have any questions you can’t find an answer to, you can ask King County at the GreenTools blog http://your.kingcounty.gov/solidwaste/greenbuilding/blog.asp?ID=12.

6 Jean, viewed another way, per posted by Andy Ault, CLC on 10/20/2010 at 03:51 am

Jean, viewed another way, perhaps "building smaller" DOES apply to retrofit / remodel work as well. Specifically, we've talked half-a-dozen clients OUT of additions in the last few years. We simply showed them how they could still get their larger master bath, kitchen, etc. by intelligently using their existing footprint. Once they saw the possibilities of good design (as Alex refers to) they realized their natural assumption that an addition was the "only" way, was flawed logic based on common consumer perceptions. Basically it follows the whole Sarah Susanka "Not So Big" concept.

I frequently make the case to fellow Remodelers that just because they're working with existing housing stock does NOT mean they are automatically earning all of the "green" brownies points they may give themselves credit for. To that end, we have an internal goal as a company to try to never build another project which will require new concrete in the ground. Basically to either build within, build up, or cantilever out as efficiently as we can. That may prove too lofty, but so far we're going on four years since we set that and we've been able to stick to it and still build some pretty amazing remodels.

7 Love the series. Keep em com posted by Bill Swanson on 10/20/2010 at 06:01 am

Love the series. Keep em coming. Seems like everything so far should be higher on the list. Building smaller saves energy, materials, waste, and green space. Looking forward to see what rounds out the top spots.

8 Although new build small plat posted by Jean Carroon on 10/19/2010 at 01:56 pm

Although new build small platinum is certainly better than new build big platinum or new builld no platinum, it is hardly a regenerative strategy.

Material use reduction is exceptionally important to environmental sustainability and human health. According to an EPA study from June 2009, Sustainable Materials Management: The Road Ahead, new construction as an industry is responsible for 49% of all resource use in the U.S., is 2nd in Global Warming Impact only to electric services and is the #1 cause of releases toxic to humans, (followed by electric services, vehicle bodies and hospitals).

If we reuse a building that already exists, minimize construction waste and new materials, extend service life (Priority #6) , increase occupant density and decrease operational/lifestyle impacts (Priority #10) and water, energy and resource use in general this is the greenest thing we can do or so say studies from Canada, England and Scotland, where far more attention is being paid to overall carbon, water and toxity impacts and not just energy use intensity which is a misleading metric as Alex points out.

Note that renovation creates 20-30% more jobs than the same investment in new construction, where the bulk of the jobs are tied to manufacturing so it is also socially and economically more sustainable. I appreciate the message of No. 5, but suggest that it should be - Reuse first and if you must build, build smaller and smarter - but maybe building reuse is being saved for No. 1? I hope so.


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