Each month we publish a newsletter titled IAQ Website of the Month. The excerpt below was originally published in the May 2010 newsletter.
Joe Lstiburek is a name that is synonymous with B.S. (building science, of course). If you have seen him speak or have read his articles in the ASHRAE Journal, you’ll agree that he is both peerless and fearless.
Joe is a principal at Building Science Corporation, a company that maintains the best building science website on the internet. What’s it all about? Here’s the description on the website
“building science.com provides objective, high-quality information about buildings. This resource combines building physics, systems design concepts, and an awareness of sustainability to promote the design and construction of buildings that are more durable, healthier, more sustainable and more economical than most buildings built today.”
The are innumerable resources divided into digests, insights, primers, reports, case studies, and more. I recommend setting aside an afternoon to read through all the free materials.
Here are some of my favorites:
If you need more irreverent commentary on the built environment, attend a Building Science Corporation seminar or purchase one of their excellent publications.
To visit this month’s featured website, click: Building Science Corporation
To subscribe to this newsletter click the following link: IAQ Website of the Month
I set aside an hour to write a blog post before I headed off to Michigan for Thanksgiving. 45 minutes of that hour was taken up speaking to an acquaintance with a residential construction nightmare story. I’ll share his quick story in the 15 (now 14) minutes I have before my wife picks me up for our family trip.
This individual had plans drafted up for an energy efficient home with promised good indoor air quality. The builder, it appears, didn’t reference those plans too carefully. A ground source heat pump (a.k.a. geothermal) was installed to heat and cool the home located in the Chicagoland area. This can only work if the walls are extremely well insulated. Although the plans called for rigid foam insulation on the exterior of the sheathing along with superior cavity insulation, all he got was some blown-in cellulose in 2×4 (not 2×6) walls.
That missing rigid foam insulation is causing two problems. The first is related to heat transfer. The foam insulation is there to help prevent thermal bridging. When you have insulation only between studs, heat will often be transferred through the wood studs. Remember: drywall is in direct contact with the wood framing. The wood framing is in direct contact with the sheathing. The sheathing is in direct contact with the cold weather. Thermal bridging is when all that great insulation gets bypassed, leaving cold spots on the wall in the winter time. Thermal bridging also occurs in the summer time, but in the opposite direction.
The second problem caused by the lack of rigid foam insulation on the exterior of the sheathing is that the ground source heat pump was sized based on the additional R value it provides. Without it, the home is colder in the winter, and warmer in the summer. Now he is looking for ways to supplement the heating and cooling because the geothermal system isn’t cutting it.
Time doesn’t permit me to go into all of the other problems we discussed. Here are some of my favorites:
- Bathroom exhaust fan dumping humid air into attic, not the outdoors
- Exhaust fans allowing cold attic air to dump down into the bathroom
- Improper weeps at the base of the brick facade
- Only a feeble attempt at zoning the HVAC system that greatly missed the mark
- Batt insulation with the kraft paper facing the wrong direction (visible mold growth discovered)
- No humidifier installed, which is needed in the winter because of the air leakage
- R-13 walls where R-30 was in the design
Well my time is up. Have a great Thanksgiving! I know I have so much to be thankful for!
Psycho-metrics is a measure of how psycho you are. That can be a helpful measurement when dealing with clients who are driving you crazy. Today, I want to give a brief introduction to something different, called psychrometrics (notice the “r”). Psychrometrics is the study of the physical and energy related (thermodynamic) properties of air-water vapor mixtures.
The first response I get when teaching psychrometrics is, “Why do I need to know this stuff?” With an understanding of psychrometrics, we can better predict where condensation may form, causing water damage and leading to indoor air quality concerns. By understand these concepts, you’ll be better able to look at a wall assembly and identify common problems.
Some of the key variables of psychrometrics include temperature, relative humidity, humidity ratio, and dew point temperature. Before we get too deep, we need to answer the question, “What is air?” Continue reading