How to ensure energy efficiency/green building with a GC who is not experienced in energy/green techniques?
Adam_S_1
| Posted in Energy Efficiency and Durability on
I am planning to build a green, energy efficient modular house in CT (shooting for around 45 HERS). The modular company bills itself as green/efficiency-savvy, but its local rep who will serve as the GC is not energy-savvy (and does not claim to be). The GC is open to hiring subs that we recommend and working with others to achieve our goals.
Apart from relying on the modular company, how can I ensure that the GC does what needs to be done and does it properly? Would I hire an energy consultant or an architect who would serve as a consultant? Thanks in advance.
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Replies
Adam,
Ordinarily, a homeowner building a house would not choose a GC who doesn't understand building concepts that are important to the homeowner. You may be setting yourself up for disappointment.
Most architects aren't able to spend much time on the job site. You can hire an energy consultant (or a savvy clerk-of-the-works) to supervise construction, I suppose, but that's likely to be expensive.
Adam,
I think the homeowner has to do it or do some serious education of the GC before the home is built. Give your GC a membership to this site. Inspect the site every single day you can. If you are building a modular home, the home gets put together really quickly which can allow serious air gaps to happen before you have time to intervene. If they put the shell together quickly take that week off so you can be there and see the fit and how the well the air sealing is done.
See Jeremy's post on condensation from his ceiling probably due to failure to fit the SIPs together well and then air seal them.
https://www.greenbuildingadvisor.com/community/forum/general-questions/42466/cathedral-sips-are-sweating-summer
And hold your contractor to a blower door result - pick a number you think is reasonable (0.6 ACH50 for the passive house standard,1 for a very good house, 2 for much better than average, etc). If he doesn't meet the agreed upon standard, he has to fix it on his own (meaning his own money) until the home meets that standard. That is effective motivation for most people.
I hear Martin's advice about choosing a GC, but some areas of the country just don't have to same level of knowledge among contractors that those in the Northeast have. It is up to us as consumers and homeowners in these other areas to drive this education cycle.
Thanks. Assuming I go with this builder, most of the work will be done in the factory, where presumably the workers have the necessary expertise/sophistication. Things like windows, HVAC would be installed in the factory. For the on-site portion, what would be the main areas on which to concentrate education/oversight efforts? I assume those areas would be insulation of the foundation and sealing the structure. What else? Thanks.
Adam,
I recommend you visit the factory and visit some completed homes. Get the details on how the hidden duct work will be installed. I have audited several older modular homes. The 2 story homes had a large chaseway run from the basement or crawlspace up thru the center of the home and into the attic for a trunk line to service the upper level. A local HVAC contractor completed the installation of supplies to the rooms and installation of the equipment. More than one of these homes had very poor airflow to the upper level. The chase was not sealed on any of these homes. The attic Batt insulation was still compressed from when the rafters were laid flat for transport. The gaps where the modules are joined were not sealed. I could look down from the attic and into the wall cavity between modules.