The Perfect House – Why Efficiency Is Not Enough

We often get asked, “What’s the best way to build a house?” Of course, there is no simple answer to this question. The best way to build a house is largely a matter of personal preference, informed by personal values, experiences, aesthetics, and our particular world view. And all of this gets reeled in by the availability of materials and local skills, costs, time limits, building code compliance, site restrictions, climate, local ordinances, etc. With so many variables to consider, there is no one-size-fits-all solution. The following list should, however, give you some real, tangible design guidelines for creating a home that is efficient, healthy, beautiful, and affordable.

The Sun is Your Friend

Energy efficiency is the primary focus of “green” homes today. Homes are tighter, they contain more insulation than in the past, windows are higher performing, and mechanical systems are more efficient. Building codes are pushing energy efficiency but the codes alone don’t go far enough.

The truth is, we’ve had the technology to build net-zero homes for decades but the political will was lacking; it still is. But the technology is still there and believe it or not, it’s largely passive. With sufficient insulation, good detailing to eliminate thermal bridging, and by balancing the glass-to-mass ratio, you can dramatically cut the amount of heating and cooling a building needs. This last point, glass-to-mass ratio, is achieved through calculated house orientation and window placement, balanced with enough thermal mass to store that heat as the sun fades away. A good example of this is an earthen (or concrete) floor placed in front of a bank of south facing windows, thus warming during the day and releasing the stored heat through the night.

Passive house illustrated by Albert, Righter and Tittmann Architects

Passive house illustrated by Albert, Righter and Tittmann Architects

 

Embodied Energy Matters

Energy efficiency is a big focus in home construction today, and more so with Passivhaus, or Net-Zero energy homes. The objective has been to minimize the amount of energy needed to run a building because, as lifecycle studies have shown, most (more than 80%) of a home’s impact is associated with the energy used operating it (vs. building it or disposing of it). This understanding has been a rationalization towards using high embodied energy – all the non-renewable energy consumed in the gathering of raw materials, their processing, manufacturing, transportation, and construction – materials (foam products for example) as an acceptable “cost” so long as the home uses less energy throughout it’s operational life. But as all homes become more energy efficient, and because building a high performance home using straw bales is just as plausible as building one with SIP panels made from OSB and XPS foam, the ratio of embodied energy contained in the materials begins to increase relative to the operational energy. Consideration of the energy contained in materials is essential if one’s aim is to create a home of minimal impact on the environment.

Embodied energy of building materials.

Embodied energy chart of building materials from www.canadianarchitect.com

Build a Glove Not a Warehouse

You’ve heard it before, since WWII the average Canadian home has increased from 800 square feet to 2,200 square feet today, even though family size has dropped. Instead of 300 square feet per person, we’re building for 1000 square feet per person. Canadians are also supporting an $8 billion a year self-storage industry to store the toys and knick-knacks that won’t fit in their growing houses.

The truth is, it is far easier to reduce the impact of a home by building smaller than by substituting low-embodied energy materials and building larger. Through sensible and logical design it is possible to build a small house that lives large. Well designed homes of 700 to 1,200 square feet should be the norm, returning to a more sensible 300 or so square feet per person.

Pattern of space use. Image-By J_Arnold.

Pattern of space use. Image-By J_Arnold.

Quality over Quantity

Chances are when it comes time to build a home you’ll have a fixed budget. At this point you’ll be left with a choice: build larger and skimp on the details or rein in the square footage and invest in quality. Going smaller means that you can add extra insulation where it matters, choose fiberglass windows over vinyl, go with a timber-frame instead of stick framing, use earthen plasters instead of paint, choose solid wood instead of laminate for your floors, and go with wooden cabinets over ones made of particleboard. You can also afford to choose healthier building products, like low VOC caulking and construction adhesives, paints, non-formaldehyde plywood, etc, which tend to come at a slight premium. It also allows room to invest in craftsmanship instead of mass manufactured materials and quality items, whether windows, cabinets, or flooring, has the added benefit of lasting longer and wearing more gracefully.

Durability

Vulnerable details should be designed out. Details that protect the building, such as designing deep roof overhangs and setting windows back away from the face of the wall, should be an integral part of the design. Durable buildings reduce the use of resources and energy needed to provide and maintain houses over a life time. It’s important though to balance durable products against their environmental impact.

 

Straw bale building with deep roof overhangs.

 

Detoxify

Chemicals that adversely impact health are found in a growing number of building materials and home furnishings. Many manufactured wood products (particle board, plywood, OSB, MDF) use formaldehyde-based resins, while adhesives, upholstery, carpets, and other plastics emit volatile organic compounds (VOCs) which are shown to erode health. And because there has been a dramatic increase in the use of foam insulation products in home building, the amount of brominated flame retardants, perhaps some of the most persistently toxic chemicals in use today, is also on the rise.

These health impacts extend to the workers manufacturing these materials, to the installers using the products, to the people living in the home after they are installed, and to firefighters who must deal with the full brunt of these chemicals when a house goes up in flames. We must shift to using healthier, more natural materials, and where no natural substitute exists, using better chemistry to make less harmful products.

Build to Adapt

A home undergoes various cycles of change throughout its lifetime. In fact, homes that are built to adapt tend to have longer lifetimes. According to Stuart Brand, author of How Buildings Learn: What Happens After They are Built, “Houses should be designed so that the short-life layers can be changed independently of the long-life structure.” He speaks of the six S’s which show the various cycles of change that should be factored into the design:

  • Site. This is eternal
  • Structure. The foundations and load-bearing elements are difficult and expensive to change. These are the essential, unchanging building which may last 30 to 300 years.
  • Skin. The envelope of a building may change every 20 years or so, to keep up with improvements of thermal performance for instance, or to replace parts which have deteriorated.
  • Services. Wiring, plumbing, ventilation and heating systems and lifts, all of which wear out or need to be upgraded at between 10- and 15-year intervals.
  • Space plan. Interior layout, which may change frequently in offices, but at perhaps 15- to 30- year intervals in housing.
  • Stuff. Furniture and equipment that are moving around all the time.

Simplicity

Christopher Alexander’s, author of A Pattern Language, suggests that a building design be simple and straightforward so it will not be too expensive to build and so that ordinary people can help in the construction process. I couldn’t agree more.

Final Thoughts

There’s a lot that goes into making a good house. It’s a balancing act and requires a lot of thoughtful planning. Take the time early on to work through these influencing factors and get the advice from those that have come before you.

 

 

 

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