Too Much of a Good Thing: The Balance Between Building Envelope and Occupancy Comfort
April 08, 2013
A building envelope is the outer shell of the building that is used to help maintain the indoor environment and control its climate. There’s been a lot of discussion in the high performance building industry about how to leverage this component efficiently and how to manage any trade-offs with occupant comfort, so I read with interest this article from Consulting-Specifying Engineer Magazine about testing and commissioning best practices.
One of the main challenges for commercial building envelope testing has been the lack of standards. Although there is still no official list of best practices (or any that are widely used), the industry has started to adopt some uniform testing procedures, including:
Air intrusion: Find and identify air leaks that are contributing to inefficiencies or occupant discomfort.
Water intrusion: Spray water against windows, doors and wall assemblies when the building is under negative pressure to help locate leaks. Spraying roofs (but not flooding them) is also recommended.
Thermal intrusion: Take a thermal image of envelope components to help identify wall or roof areas where heat is leaking out or in. It can also show thermal bridging of structural elements when the building is under test pressure.
The most difficult part of the testing is when you must strike the balance between acceptable leak rates and the environment for workers inside the building. For example, thermal intrusion may be a trade-off between envelope mass and material thermal resistance versus the views through glazed openings. On the other hand, smaller areas of glazing can improve the thermal resistance, but without enough of it, natural light and views are affected.
Some areas of the journey to a high performance building outcome are black and white: which solutions perform the best, which technology manages operations to maximum efficiency, etc. But there are always trade-offs, as the article discussed.
When we at Trane work with customers on new buildings, we have these same discussions to help balance the need for occupant comfort and productivity while ensuring that the building operates at peak performance.
If you are constructing a new building, make sure you have a frank discussion with your consultants about balancing the many factors that go into ensuring a building is performing at maximum efficiency. After all, the mark of a true high performance buildings is not having to sacrifice occupant comfort or enjoyment of the space in order to maintain efficiency.