We chose to pursue LEED certification for our home as a way of measuring our level of green building design and construction. Leadership in Energy and Environmental Design is an internationally recognized green building certification system, providing third-party verification that a building or community was designed and built using strategies aimed at improving performance across all the metrics that matter most: energy savings, water efficiency, CO2 emissions reduction, improved indoor environmental quality, and stewardship of resources and sensitivity to their impacts. LEED was developed by the U.S. Green Building Council.
As of October 2010 our home officially earned a LEED Platinum rating, which is the highest of 4 levels of certification offered by the USGBC. We achieved a HERS index of 20, which we believe is the lowest (best) index to date in the state of Michigan. An index of 20 indicates that a home uses only 20% of the energy that a standard new home uses, while an index of 0 would be awarded to a zero-energy home that produces (through renewable sources such as solar and wind) as much energy as it consumes on an annual basis.
This HERS index is determined by a computer modeling program and it may not accurately model homes like ours whose design is substantially outside the norm. We believe that we'll actually produce an annual surplus of energy, earning a negative HERS index, but that remains to be proven. We're keeping careful records and we will have a full 12 months of data by the end of March 2011.
For a builder who is building a spec home, getting LEED certification has the obvious advantage of providing a higher selling price because consumers will pay more for a home that is certified to be highly energy efficient and built to environmentally-friendly standards. But for independent owner-builders like us, the advantages are less tangible. There are direct costs involved in getting LEED certification, which will amount to roughly $2500 in our case. We don't get any direct payback for this expenditure, except perhaps a certificate to hang on the wall. So why did we go to the trouble and expense? One reason we're publishing this web site is in hopes of helping others who may learn from our successes and our mistakes, and LEED certification gives a certain amount of instant credibility. We can wave our hands and say how great our house is, but having LEED certification is a much more credible proof that the house actually meets our goals of energy efficiency and environmentally responsible design.
The LEED for Homes rating system is freely available and one can build a home to these standards without paying anything or going through the formal rating process. We considered going that route, i.e. using the LEED guidelines to help us build better but not going to the expense of actual certification. But there's really nothing like having independent verification by an inspector (our "green rater") to motivate one to take the rating criteria seriously. As it turned out, we found a number of unexpected and direct benefits from going through LEED certification that more than paid for its cost:
- LEED awards points for using recycled and reclaimed materials, so we searched out and found a source of post-consumer reclaimed foam insulation that we used under the floor slabs. Instead of new insulation made from virgin petroleum, we used reclaimed material that might otherwise have been sent to a landfill. That made us feel good, but it also turned out to be cheaper than buying new insulation. Because we used so much foam under the floors, this ended up saving us about $2000 compared to buying it at a home center.
- One of the rating metrics is how much scrap material is recycled versus that which is sent to a landfill. More points are awarded to construction projects that generate extremely little trash by recycling as much as possible. Therefore we looked for ways to recycle our scraps rather than simply sending them to the landfill. As it turns out, recycling is also considerably cheaper. In the case of drywall we paid only a small fee for having the drywall scraps hauled away to be recycled as a soil amendment. Similarly we found a recycler that accepts wood scraps for free, even with nails, which saved additional dumpster space. We estimate that our direct cost savings from recycling these materials was about $500.
- Our green rater inspected and identified some gaps in our wall insulation, at a time when we could still correct the problem. This will save us a significant amount of heat loss that would otherwise have made our "superinsulated" home not so super. He also came back and checked for heat loss using thermal imaging, and found a major insulation gap that we can fix now that we know about it. It's hard to measure the value of this in dollars but it could easily have added $100 per year in energy costs for the life of the building.
- The rating system awards a credit for controlling indoor contamination by placing "permanent walk-off mats" at every entrance. We liked this idea and so we had recesses formed in the concrete slabs at every entrance to hold metal doormats with the top at floor level, allowing dirt to drop through. We wouldn't have thought of it if it weren't for LEED. Although we won't get any points for this because the rating system requires the mats to be four feet long and our mats aren't that big, we still benefit from the idea by reducing the amount of dirt entering the home.
- We followed the LEED requirement to seal all ventilation ducts as soon as they were installed, to prevent dust accumulation during construction. In order to reduce air leakage from the ducts (one of the measurements that will be taken by our green rater), we also sealed every seam with duct mastic. These measures will greatly reduce the dust level and air leakage from our ductwork, and we probably wouldn't have thought of them if we weren't pursuing LEED certification.
For more information about the specific features of our home that qualify for LEED credits, click here.