Testing and Assessing the Building Envelope

The building envelope is the boundary between conditioned and unconditioned spaces in your house. It has two key components: the air barrier and the insulation. The building envelope goes around the entire perimeter of the house because it is, by definition the boundary between conditioned and unconditioned air. Therefore, all homes have a boundary envelope . It might be very leaky. It might be poorly insulated. But it is there. Your energy auditor will check these 3 components on all facets of your home to check on its quality. There are 3 critical components to check.

  1. Integrity of the air barrier. This will be examined by visual inspection and then later tested with a blower door test. We describe a blower door test here. The visual inspection helps identify the big leaks. The open chases, the hidden  open chases- you never know what gets covered up over the years, as older home have been bent and folded to fit with modern ideas of home interiors.
  2. He will check on the insulation in all facets of the boundary layer. Is there insulation in the attic, how much, how well it is dispersed?
  3. He will  also check for the alignment of the insulation with the air barrier. Insulations, like fiberglass and cellulose, does not stop air leaking in and out. That is the job of the air barrier. In fact, don’t let anyone sell you a special deal on insulation – would you like insulation with that order?  until you know how well your air barrier is working. The insulation needs to be fit snugly without gaps against the air barrier, otherwise, hot and humid ambient air in direct contact with an air barrier in a cooled Texas home can create a condensation problem.

Which brings us to another key tool – thermal imaging.

You auditor may or may not bring this tool to the table. And then if they do they have to be well trained in its use. Thermal imaging can catch issues that just do not show up otherwise. This can help nip problems in the budding. Thermal imaging is not a panacea. The results need to be confirmed; but used effectively, thermal imaging is a powerful tool- that can really help. We talk more about thermal imaging here.

Make sure your energy audit is not just somebody’s marketing tool.

Any kind of energy audit not backed by building science is most likely not addressing the issues impacting your energy bill. It will be up to you to figure out if someone is trying to sell you something or trying to help you solve a problem. Here is a caveat for you.

Here is a return to the larger issues involved in an  understanding the energy audit. There are many more critical tests and results of the audit system.

Cooling and heating issues- both ducting and HVAC equipment- play a key role  in an audit.

Feel free to ask a question or add  a  comment below.

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