It is a classic conversation in the home building industry, the moves as well rehearsed as the opening of a chess game between two champions. There is an obvious, logical path and arguments for both sides when it comes to the adoption of new technologies and codes and builders’ general resistance to change.
Every green home verifier I know has been asked by a builder, “How green could it really be to air seal my house to such a level that I have to bring in make-up air through mechanical ventilation? Why not just let the house ‘breathe’ naturally by not sealing it up so tight?” This question, and others like it generated by new technology and codes, is one of the best reasons to have an expert verify your home based on the practices of the National Green Building Standard (NGBS). If you were building homes under the NGBS, you would have been asking this question back in 2008, if not earlier. Now it’s 2014, the 2012 International Energy Conservation Code (IECC) is gaining ground and being accepted in many states, and these are no longer questions of “if” but “when” you will be required to meet a certain building leakage number. If you already addressed this issue back in ’08, you’ve nothing to fear. The most current version of the NGBS brings you to the cutting edge of the building industry in terms of new technologies and code changes, which are evolving the industry into something totally different then when we were kids.
That being said, there are codes that make sense, and codes that don’t. During my last conversation that started off with the above question, a builder reminded me of a building code in the 70’s which required plastic (poly) to be stapled over insulation before the installation of drywall. That was stupid; no wonder builders are cautious. But now the industry and its practitioners have evolved. Building technology and innovation has grown into a field of study all its own. Builders need a person whose entire job is to stay up on the changes; someone whose job it is to help decipher which changes are to be embraced and which are to be fought. That person is an accredited verifier.
As a green home building verifier and advocate for high-performance, efficient construction, many people assume I embrace all the changes in the building code that seem to ratchet up energy- and resource-efficiency, but I don’t. I only embrace those that make sense from a building science perspective! To use an example from the 2012 IECC, I don’t think the wholesale installation of hot water pipe insulation (HWPI) makes sense. In my area of the country, many builders use a parallel piping system – the type of system where the hub looks like a spider with red and blue legs sprouting from the sides. A parallel piping system saves about 33 percent energy use over traditional piping. Now, even if you forget the exponential increase in the cost of HWPI between traditional piping and a parallel piping system (which can be around $300), think of the logistics. The difference (besides cost) is putting a two-inch hole through walls, TJIs, and possibly an LVL, and putting nine or more two-inch holes through all the same places. My point is if HWPI is mandated the way it is currently written, builders are more likely to revert to a traditional piping system and lose the 33 percent energy savings in favor of HWPI, which saves less energy.
In cases like this, you need that person there arguing on your behalf for something that makes sense – like an exception in the code for parallel piping systems. Before the NGBS became prominent, there were very few builders in my area who even knew what a parallel piping system was. It’s all about staying on the cutting edge, being ahead of the pack. And enlisting the help of a trained, accredited verifier and a rating system like the NGBS can do just that.
Back to our original question – why seal the house then bring in make-up air? There are plenty of sound reasons:
- Improved Punch Out: You want to reduce nail pops and drywall cracks? The best way to do that is to reduce air movement and temperature differentiation within the wall. I work with a builder whose punch out list at the one-year walk is very limited.
- Improved Air Quality: Which would you rather be breathing, the air that seeped through all of the little cracks in the house or air that was brought in intentionally and filtered before use?
- Energy Savings: The use of point source air allows for a heat recovery ventilator (HRV) or an energy recovery ventilator (ERV) to be installed, saving precious energy and nullifying the argument of wasting conditioned air through mechanical ventilation.
- Cleanliness: What lives in the aforementioned cracks in the building envelope? Dust. Along with eliminating dust, the elimination of cob webs is another benefit of a well-sealed house. No self-respecting spider would make a web where there is no air flow – no chance of catching anything!
So here’s the bottom line (conveniently located at the bottom of my post!). Why certify under the NGBS? Being at the cutting edge of the innovation implementation curve allows you more time for adjusting to the evolution of our industry. To know what’s out there, to see it coming, and to adjust accordingly. A third-party expert armed with a consensus-based “roadmap” like the National Green Building Standard is necessary to help you navigate today’s building world.