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Apr 16, 2012

Nice House, But Is It Legal?


If you designed or built a home that met energy code just a few years ago, that same home will probably not be legal to build just a few years from now. Some might say it’s about time, while others may think it’s not a good idea to increase code requirements during a depressed housing economy.

For over 25 years, residential energy codes improved an average of less than 1 percent per year. But since adoption of the 2006 International Energy Conservation Code (IECC), codes are improving radically—perhaps by as much as 50 percent when the 2015 IECC is published.

I haven’t met anyone who thinks energy costs will decrease, and almost everyone would appreciate smaller energy bills and lower emissions from their regional power plant. However, some builders think a slow housing market is not the time to add cost to a home. As recently reported by MINNPOST, Minnesota builders are voicing objections to potential increased costs for more efficient building codes.

At Rocky Mountain Institute, we purposely launched our Superefficient Housing Initiative at nearly the lowest point in this housing economy because it made sense to us. If a builder, developer, or designer is going to learn or try something new—or build on his/her brand with a new product offering, there’s really no better time than when the market is slow. You’re certainly not going to retool your design and construction approach when you’re really busy designing or building homes.

Our initiative set out to prove that housing can be designed and constructed to be 60 percent more efficient than the 2006 IECC, for about the same cost as just meeting the code. We didn’t set this target arbitrarily—we started by scanning the horizon of existing codes, standards, and guidelines. And there are a surprisingly large number of them—representing a wide range of energy targets and goals. I have attempted to rank these on a Home Energy Rating System (HERS) scale for relative comparison in the graph below.

While most of these codes and standards don’t dismiss aggressive energy performance, they also don’t necessarily require it. Therefore, “your mileage may vary” when applying a specific code or standard to a new home or building. While codes are a critical part of the energy solution, we need scalable, affordable solutions today to get ahead of the new codes and avert the detrimental effects of inefficient buildings. Between 2010 and 2050, the U.S. housing stock will change dramatically—with new construction, demolition, and replacements, we will add 20 billion square feet of new housing. Since the U.S. housing sector uses more energy than the commercial sector, this is our real opportunity to aim our efficiency goals well beyond code, and begin to imagine communities of energy independence.

Baseline Zero

As energy codes advance more rapidly, we also need a new way to talk about what we are aiming for. With over 3,000 code jurisdictions in the U.S., it’s nearly impossible to understand what it means when a new home is designed and constructed to be 30 percent better than code. Really? What code? Or when a new net zero energy house has a large photovoltaic array on the roof and includes a heating system, a cooling system, and a ventilation system (in a relatively mild climate), you have to ask yourself whether it’s efficient or not.

If the design and construction community were able to communicate energy efficiency in a new way—for instance from a baseline of zero up as opposed to top down (from the maximum allowed by code)—we might begin to have conversations that move us closer to where we need to be. Forget net zero; how close to zero before renewable energy supply is a better comparison model.

Simple Solutions

I am personally excited about the Passivhaus energy standard as a relatively new movement here in the U.S. The Passivhaus (Passive House) approach, originated in Germany, and is what I consider the world’s most aggressive energy efficiency standard.

The Passive House standard can apply to design, construction and retrofit of our schools, offices, and homes, and uses between 80 and 90 percent less heating or cooling energy than typical existing stock. While it is isn’t free to build this way, the economics will improve as more and more manufacturers of windows, insulation, and ventilation units see increased demand and innovate on their current models.

When it comes to simple solutions, based on my building science knowledge and experience, this I know to be true: a tight building envelope with superior (tuned and optimized) windows and little or no thermal bridging is the best bang for the buck. If these elements are truly optimized for climate, then you only need to worry about what you don’t need to do, such as eliminating air conditioning or perimeter heating, and getting excellent indoor air quality using a small ventilation system.

We also need whole-house retrofits that approach or even meet the Passive House standard. A few of these projects are beginning to show up in California and the Pacific Northwest. Whether they meet the standard isn’t the point; it’s all about making significant reductions to current energy use to provide resilience for the new energy era at our doorstep.


Showing 1-10 of 11 comments

April 18, 2012

Based on the experience in Germany, this approach appears much too weak and much too naive. There should be much more clever and much more efficient solutions, to safe energy today...

April 18, 2012

Mine is Energy Positive ,not just zero energy and includes my transportation. So keep going to much more efficient homes.

I have a 4 Kw GRID Tied system and improved my 15 year old home to be very efficient, I drive a Nissan LEAF and still get over 1,000 KwH credit from my utiltiy at the end of each year.
We only use LED lights, 1 have solar PV and Hot Water, a 16.5 SERR heat pump, solar tube lights, solar screens, inflectors on all windows, radiant barrier in the attic and have NO Fireplace or other fuels.

We are in Sunny Arizona which helps a lot. Germany the leader in Solar use gets only 60% of the solar we get.

April 18, 2012

Passivehaus is a simple and effective energy saving standard. The low tech energy efficent design and special building practices are confirmed by thousands of near net zero homes build around the world. Contrasted with the expensive high tech intensive approach of heavy use of solar panels and ground source heat pumps, etc to acheive NET-zero the Passivhaus' simplicity and lack of mechanicals is its strengths. The least expensive watt you buy is the one you didn't have to produce!

April 18, 2012

Too many ratings systems give a "score" or "grade" based on energy usage per s.f. or how the home stacks up to a comparable home built just to code. It's hard to explain to people that a large house with a better HERS rating can actually use more energy than a smaller home with a slightly worse HERS score. How about a scoring system for homes based on real energy usage? One that would show buyers the projected energy usage of a home (or the actual energy usage in the case of existing homes). Much like a miles per gallon rating, every home is scored on the same metric and you can compare homes of differing sizes to each other.

April 18, 2012

Interestingly, the "International Energy Code" is not international - it is generated by a US-based organization and is only used domestically, i.e., by US states and dependencies.

The Passivhaus concept is not particularly innovative - the techniques applied have been tried in various experimental buildings since the 1950s. From a practical perspective, most of the measures proposed will be of little benefit or simply cannot be implemented - the windmill in the back yard for example, dependence on access to sunlight during winter when demand for energy is highest in most parts of North America, especially the northern US and in Canada, and passing fresh air through the ground before it enters the residence in areas prone to Radon gas emissions. Insulating walls to R38 itself presents some challenges in the construction of wood framed buildings and certainly adds to the capital cost. Ensuring that the insulating effect is actually achieved tends to be problematic in mass construction projects. Sealing the building has proven to be a serious source of health problems wherever the climate is mild and damp and wind driven rain or inadequate ventilation of the interior spaces results in condensation within the envelope - mold growth has resulted in the condemnation or premature rehabilitation/reconstruction of multi-family residential units and single family houses in certain regions of the continent. Policy prescriptions for high insulation values and low infiltration rates (sealed houses) improperly applied can lead to undesirable realizations.

A useful reference for residential and commercial design in the U.S. is a book by Victor Olgyay titled "Design with Climate - Bioclimatic Approach to Architectural Regionalism", 1963. Princeton, NJ: Princeton University Press.

Contrary to Mr. Brew's statement regarding energy cost, recent natural gas prices have fallen below historical levels on a constant dollar basis. This has had the effect of reducing the cost of generated electricity, as well as reducing the cost of home heating if natural gas is the heating fuel. Commodity prices tend to surprise from time to time and put paid to any broadly held notions of 'normal'.

April 20, 2012

Relevant to this discussion is the highly-developed case study available at:

The owner of an engineering instruments company built a house for himself and his wife and instrumented it sixty ways from Sunday. The link above takes you to an account of the house, of its construction, and of the data documenting its properties. I've seen the house, and it is striking in its livability. The company offers services to others interested in building cutting-edge homes, including ones with exteriors that are very conventional looking.

Of particular interest is (from the site): "An advanced technology comfort conditioning system (called a CERV, pronounced “serve”, Conditioning Energy Recovery Ventilator) developed by Newell Instruments provides the capability to monitor and control temperature and humidity levels in the house at all times."

April 20, 2012

Passivhaus is in en exciting phase here in NYC. Builders and Architects are finding the question of increased cost (and presumed complexity of detail) to be less scary than anticipated. The learning curve is high too between the first and following projects. Less mechanical systems to pay for and cram in a building really is an upside that's easy to convey to clients.

April 22, 2012

Passive House is one of the most promising standards/energy design tools/construction methodologies available today. The core principal of first designing the most efficient envelope possible then supplementing that with active systems and renewables is the ideal way to achieve net-zero (or, better yet, energy positive) buildings.

Not only will these building stay 'legal' well into the future but, as energy prices continue to increase, the benefits of sustainability will cause rents, resale values, demand, etc to be significantly higher than for comparable buildings that only meet current minimums required by code.

In response to 'braemarinvestments' comment below: these issues mentioned are either not applicable to Passive House or are the result of incorrect or incomplete application of Passive House principals. Properly executed, a Passive House building will not experience the problems you discuss.

October 19, 2012

Response to Joel Zook,
I agree that all the scoring systems are out of whack.
The dollar is the best unit for an EPA style score (dollars/year), and it leaves square footage completely out.

For more on this: http://greenbuildingindenver.blogspot.com/2010/10/leed-for-homes-rating-system.html

November 29, 2012

PASSIVHAUS - this is the baseline for my clients. each of them after retrofit (+addition most of the time) are astonished by the comfort of their home afterwards. [like driving a Ferrari]. Simplest way is to re-skinning the existing house with R=25+ foam with nailer, and fill existing cavity with batt or equal. Avoiding foam for many reasons. Roof I generally build up the same way and batt for the joists. R=80 is optimum where ever in US for both summer heat gain or winter heat loss reasons. For picture windows at least I prefer R=13 high efficiency 'Heatmirror' by Southwall, and the combination is a win win, as heating and cooling becomes negligible, taken care by tiny geo thermal unit(s) and solar PV... and as an extreme back up, a small wood burning stove for winter outages lasting more than 5 days...
Truly for new construction to be connected to a power grid is plain odd...

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