Tuesday, October 5, 2010

The LEED For Homes Rating System

I've been watching from the sideline, stubbornly NOT going for LEED qualification. In building code terms, LEED is far too prescriptive and not performance oriented. Throw in "too complex for real customers" and too expensive, and what you have is nearly worthless.

Here's a solution I've been mulling:

1. Let the building departments adopt the 2009 energy code as they wish. Then STOP any code changes forever, except for safety items. The technology is still changing too fast to attempt to follow it with prescriptive code "improvements". Another reason for freezing the code is to prevent those pesky unintended consequences that aren't even discovered for 20 years. (see Solar Driven Moisture in Brick Veneer at BuildingScience.com)

2. Then let builders build as they see fit. Good ones will keep improving the sustainability of their product. (If you care enough to be reading this blog, you're probably one of the good ones)

3. Here's where we replace prescriptive with performance: You can't get any sort of LEEP (Leadership in Energy Efficiency Performance) rating PRIOR to building anything. To get a LEEP rating, the home must have a simple Web-based monitoring device installed for at least one year. The cost of this should only be $1000-$3000, it only needs a handful of measurements, some of which are already there, like kwh consumption, water consumption, gas consumption. Add two indoor temperature readings, hot water tank inlet and outlet, outdoor temperature north side of house and south side of house, major appliance electricity consumption, etc.

This data can then be used to "normalize" the performance results. The square footage of the house is completely left out of the normalization calculations.

4. The LEEP rating is in dollars, the only unit that makes sense to everyone. (Just like a yellow EPA EnergyGuide label for appliances). A true net zero energy house gets a LEEP rating of $0/yr. If you put on excess PV panels, and the utility pays you for your excess production, then your LEEP rating can be calculated to equal what the utility pays you for the year, and is negative, say -$200/yr. A 1000 sq. ft. home built to 2009 code minimum might get a rating of $800/yr. A 2000 sq. ft. home built to 2009 code minimum should perform a little better per sq. ft. than the 1000sq.ft. home, so it might get a rating of $1400/yr.

This performance rating will always guide the builder in the right direction.

5. The other non-energy efficiency related metrics can have their own rating, such as LEEPdurability, and LEEPwater. A near-zero maintenance house might have a LEEPdurability rating of $30 per year, while a house that needs painting and new light bulbs often would be rated at $300/yr. Again, the LEEPwater rating is in $/yr. Oh yeah, don't forget LEEPembodiedenergy. That could be in kwh.

The ratings are thus understandable, simple, standardized, and allow the builder his own solutions rather than any suggested by LEED.

Eventually these ratings will be meaningful to buyers, and that's when the builders learn they must generate good ratings. That's what I like, market forces in play instead of federal policy!

Since this is so similar to the appliance rating program, the LEED officials must have studied the method, but I can't figure out why they rejected it.


  1. Or... lets all jump on the Passive House (passivhaus) standard!!

    That's my suggestion at least.


  2. Passivhaus is an improvement, for sure. But some of its requirements are overkill that will become worse as the price of PV keeps dropping.
    See http://www.greenbuildingadvisor.com/blogs/dept/musings/can-foam-insulation-be-too-thick

    Green building is such a fast moving target right now that is damaged by codes and standards. Performance monitoring is the only practical solution.

  3. The Passive House standard has been predicting the energy performance of houses for over 20 years accurately. It IS a performance based standard.

    Kevin, my fundamental problem with your argument that we should just slap a huge PV array on a house is its the same logic that we used in the 50s - 90s. Energy is cheap, so build a home however you want. That is in effect the same argument you are using.

    There is no way to predict if PV will always be cheap or available.

    Its ALWAYS a better solution to conserve energy that you have than having to rely on producing new energy for the home.

    That's my thinking anyway.

  4. Seth, I understand your thinking, I'm just saying that dollars are an easy way to measure and compare energy costs.

    Conservation is not always better, and Passivhaus must recognize it.

    Here's why... what if it costs $2 in insulation to save an additional $0.50/yr? Sounds like a good investment. But what if you could spend only $1 on PV to save $0.50/yr? Well, that's a 2X better investment.

    Everyone should use whatever construction budget they have to save the most money they can. A carbon tax might penalize PV a little compared to recycled cellulose, that's OK. We need to turn carbon into dollars ASAP.

    Thanks for weighing in!

  5. Yea, I guess we just disagree. I just don't see a PV array being equal to more insulation.

    Your math sounds good now. And maybe even over 5 years. But what about over the life of the home? 20 years down the road what was the better investment? 40 years down the road? 60 years?

    My money is on the insulation over the PV array after, probably, 7 years.

  6. I think I understand why you don't look at it as strict economic comparison:

    1. Wall insulation never wears out so it never needs replacing.
    2. If energy costs a lot more in the future, it will cost a LOT more to add that insulation than it would during the original construction.
    3. PV needs replacing after 30-40 years, and might cost more then. (I'm betting that it will be MUCH cheaper then).

    But there are economic tools to help us evaluate those issues, we would just have to make some reasonable assumptions.

  7. Seth,

    Here's our discussion on a national scale: