LEED for Homes - Home Size Adjustment Calculations

The Home Size Adjustment in the LEED for Homes rating system is intended to compensate for the overall effect that excessively large homes have on the environment. The size of a home effects two main aspects associated with the environment:

1. The amount of resources and raw material used to build a home and all of the embodied energy in those materials that went into producing and transporting them to the new home being built. [A 100% increase in home size yields an increase in material usage of 40% to 90%]
2. The long-term energy needs to operate the home. [A 100% increase in home size yields an increase in annual energy usage of 15% to 50%]

The Home Size Threshold Adjustment chart below shows the average size of 1 bedroom to 5 bedroom homes which is the neutral size that does not effect the LEED rating thresholds. If you build a home smaller than this neutral point, you will have point(s) deducted from each threshold (certified, silver, gold & platinum). If the home is larger than neutral, it will have points added to each threshold.

If you look at the fine print above the second chart you will notice that these calculations are based on an equation, which means that if you build a home that is even larger than the largest size shown on the first chart, your penalty will not stop at +10, but will continue up to as high as +30. For instance, if you happened to build yourself a 5,000 sf McMansion with only 3 bedrooms, you’d be in the +30 range and might as well give up on a LEED certification unless you have your own solar or wind farm in your back yard.

In the 100K House, we are building a 2 bedroom home that is 1,120 sf. This gets six points taken off of each of the thresholds and most importantly, lowers the level for a platinum rating from 90 to 84 total points for our project. I think this is by far my favorite aspect of the LEED for Homes rating system as it simultaneously discourages lousy McMansion style homes and encourages a more sensible home size that encourages a minimalist lifestyle and less consumption. In my opinion, smaller homes not only effect the environment positively, but they also can improve our lifestyles. Less space means less incentive to waste time and money purchasing junk we don’t need. This frees up more of our time and money to spend on the more important things in life such as friends, family, food, traveling and beer.

Next we jump into the first category - Innovation & Design Process