"Thanks to those who have already contributed! To clarify, we need project data submissions that have cost resolution at the measure/task level. For example, a line-item $ cost to insulate the attic to R-60, and another line item $ cost to seal and i…"
Berkeley Lab is gathering information from the industry to better understand the costs and challenges of deep energy retrofit (DER) projects in homes. We are interested in DER projects that use a comprehensive, whole-home approach to drastically red…
"My research team at LBNL has assembled a large database of envelope leakage measurements from homes across the US (>150,000 homes). The project website is under maintenance right now, but should be back up soon for interactive plotting. A number of…"
"So, here's my thinking on furring down the ridge and insulating a bit from underneath. First, it might keep the ridge above the dew point, but it could very well remain in mold growth territory above 80% RH. Second, even if the ridge was protected,…"
"Thanks Paul, do wish I had read that article earlier this year. It's frustrating that this assembly meets the letter of the model building codes, but then there's this apparent consensus that this is a sketchy or DIY practice? My insulation sub and…"
"The "blocking" is more like an undersized ridge beam running the length of the room. I'm sure it's thermally bridging and represents a hot surface, but cool enough to support condensation at likely very high vapor pressure. I think the air up there…"
Greetings, We recently placed 3.5" of RMax foil-faced polyiso foam board (air and vapor impermeable) neatly cut and placed between the rafters of our cathedralized ceiling home in the Santa Cruz Mountains of California (hot dry summer, very wet and…
"Thanks again for the thoughtful perspectives, David. I've never heard the thermal lag justification for use of 99% design conditions. Is that written in Manual J or elsewhere? Very interesting stuff, especially the linkage between using different de…"
"Dara, I've not heard of this issue before, and it's very interesting, indeed. But it sure seems like this could happen due to any number of issues, such as the operation of other exhaust devices, continuous exhaust fan, or even just any long time pe…"
"David, I know the pressure reaches static levels quickly. I meant, how quickly then does radon begin to emit or be drawn into the space at a higher rate. For example, initially drawn by depressurization into a basement and then rising up into the li…"
"Hi Don, great sequence of questions, and a couple of thoughts.
Overall, I just don't see depressurization, especially short-term and infrequent (as caused by cooking appliances), as being a major risk to health or building durability. Running a cont…"
"The DeltaQ duct leakage test uses only a blower door fan to measure duct leakage to outside at actual HVAC system pressures, as they exist/occur during system operation. So, for example, a leak at the return plenum is not treated the same as a leak…"
"Hey Chris, y'all are kicking butt!! I'm sure your new HVAC won't use any energy, because you won't turn it on, right? ;) What a cool, cool project.
On a related note, our whole region just created a community power agency (Monterey Bay Community Po…"
"Also, if it's exceptionally cold outside, you could have a supply air temp into the living space that is below the dew point. For example, if it were 70F inside and -30F outside and you have a sensible efficiency of 70% (Zehnder is higher, I think),…"