General Response I was in Denver, and attended John's presentation. There are several flaws in the metrics of the presentation, and I am preparing a detailed response. There are also studies being conducted to address this entire discussion with DATA. It is data that is missing here. Modeling, modeling, modeling. What we think will happen. I also attended Robb Aldrich's presentation, which he made at the EEBA conference in September. That study also lacks complete data. Martin, I would encourage you to attend a presentation coming up at the NESEA conference in Boston in March. Eberhard Paul from, you guessed it, Germany will be presenting on H/ERVs, and about IAQ in homes. He has done more study and data collection on the subject than anyone I know, and I think that you will find that his data and studies will have you re-think things. One study that he did concludes that opening windows is a better combined solution for IAQ and energy efficiency than using bath fans, even in cold climates. More to come. Barry Stephens
Posted: 05:45 pm on December 7th 2012
Response to Martin Martin, There will be a lot more data coming out on this subject shortly. The NorthWest Energy Efficiency Alliance has commissioned a residential ventilation study, and Washington State is doing the study. So your third party data and study is under way. I expect that 2013 will be a very interesting year for ventilation!
Posted: 02:47 pm on December 10th 2012
Heating and Cooling with Tubing in Floors Hello Martin, Thought I would weigh in with a side bar. You should pay a visit to my home in Maine, where I have a geothermal system with radiant floors, and I both heat and cool the house with the radiant system. During the winter, the COP on the geothermal system is in the 5 range, and during the summer, it is off the charts. We call it "free cooling", as I am simply running two small pumps to a plate heat exchanger, and that provides cooling. I also have an HRV with a ground-source coil for pre-heating and pre-cooling/dehumidification, and a Italian made hydronic boosted dehumidifier to manage the humidity in the house. My electric bill in June-August the last two summers was less than $50/month, and the house stays at 75F/60% humidity all summer. Using hydronic ceiling systems with heat pumps for heating and cooling is growing rapidly in Europe. So the arguments are changing. :-)
Posted: 09:28 pm on April 23rd 2014
Not all HRVs and ERVs are created equal. There are some considerations to be taken in to account with this discussion. Robert, there are significant differences in products. Efficiency can translate in to a significant difference in comfort with regards to temperature of incoming air. For example, with outside air at 30F and inside air at 70F, a ASE of 75% will result in 60F incoming air temperature, while a ASE of 90% results in incoming air at 66F. Quite a difference in comfort. Similar differences in sound levels are also an important consideration, and that is reflected in the size and insulation of the box. With regards to Max Sherman's comments on ERVs, I am hoping that LBNL will one day realize or acknowledge that ERVs vary widely, and that their assumptions are in some cases misguided. For example, ERVs with enthalpy wheels, notorious for cross-flow leakage, should not be compared to well designed and manufactured cross-counter-flow ERVs with dPoint membrane based heat and moisture exchangers. Wheels are known (and certified) to leak at 10-50%, while dPoint units are less than 3%. This is third-party verified by both HVI and PHI. So pontificating with broad-strokes declarations is misguided and incorrect. And the formaldehyde theory. Data please. I thought we had put that one to bed, pending some actual data. And again, enthalpy wheel, or otherwise? And with regards to the theory that ERVs will retain too much moisture if used for bath exhaust, can we also recognize that ERV SYSTEMS are not all created equal either? Take a typical whole house system. There would be perhaps four to five exhaust points (bathrooms, kitchen, possibly basement or mud room or laundry) and an approximately equal number of supply points. So assume a 50% RH in the home, and 90% in the bathroom with the shower going on. The bathroom with the shower going on represents 20-25% of the total exhaust flow, so 75-80% of the exhaust is at 50%, and 20-25% is at 90%. Do the math. Not as significant as presented. And that bath with shower is only intermittent, and the remainder of the time, the bathroom is at close to ambient. If the incoming air is at low humidity, you transfer some of the moisture to the incoming air. If the outside air is at high humidity, you still transfer a large percentage of incoming humidity to the outgoing air. I still don't think it makes sense to punch more leaky holes in the walls and stick bath fans in them if you have a properly designed, installed and commissioned HRV OR ERV system.
Posted: 12:35 am on May 1st 2014
ROI I hear the ROI comment continuously. And that seems to be a driver in an evolving standard. If ROI is the driver for energy efficiency, then those driving a Prius are guilty of failing miserably. There is absolutely no ROI in a Prius. Perhaps we should start to measure mpg with cars rolling down hill, in order to be more inclusive.
Posted: 01:01 pm on September 29th 2014
Passive House? Although this looks to be a very energy efficient project, it should not be considered for PAssive House certification. The use of low efficiency ERVs, non-certified, would not allow for accurate rating for Passive House. We have been having this conversation for some time, and although PHIUS seems intent on making it up as they go along, you can not plug random numbers in to the PHPP and get a result that is anything but guesswork. And in a project of this size, the margin of error becomes very significant.
Posted: 02:36 pm on November 19th 2014
Response to Martin Martin, Your comments are valid. However, whether you are building a PHI certified building, or a PHIUS certified building, there needs to be a standard. PHI has a standard for HRVs, windows, etc. Like it or not, it is a standard. PHIUS, to date, does not have a standard for HRVs. I have been requesting one for some time. The process is "in committee". So how is a project "certified" without standardized inputs?
Posted: 05:05 pm on November 19th 2014