Houses have been getting bigger. Over the past fifty plus years (until 2008), the size of the average new house more than doubled, from 1,000 square feet or less in 1950 to 2,265 in 2000 (values from NAHB). The percentage of new homes smaller than 1,200 square feet has been dropping since 1987, while the percentage of new homes larger than 2,400 grew from 21% to 38% between 1987 and 2001 (values from this study). Interestingly, the size of the average new home dropped in 2008 (data here and an article here).
The general trend of larger and larger houses has a direct impact on the environment. Larger houses require more land to build on, more materials for construction, more energy to heat, cool, and light, and result in more waste, both during construction and demolition. While it is expected that there may be some “economy of scale” as houses get larger, there is a widely held suspicion that larger homes consume proportionally more materials because they often have higher ceilings and more complex geometry. Larger houses also require more materials to furnish and decorate.
It should be noted that larger homes are not only increasing in area (square footage); they are also increasing in volume, which may ultimately have a larger impact on the energy consumption of the house. Larger houses are usually constructed with extra features that are not surface area efficient (such as complicated roofs and dormer windows) and which consume more energy for heating and cooling than a compact house of the same volume.
New houses should be both smaller and more compact.
However, it has been difficult to build smaller homes. Aside from the social cache afforded those with larger homes, zoning rules and mortgage practices have also pushed “bigger is better.” For example, mortgage lenders often required the home to be “three times the value of the land,” which then determined a minimum house size for a certain area.
The recent, slight tilt towards smaller home is likely due to the recession and the constrained finances of those building, financing and buying homes. But it is encouraging. When considering what they could afford financially, people chose smaller houses. If we consider what we can “afford” using metrics of energy, water, and materials, we should prioritize building smaller houses.