The residences at Melpet Farm is an affordable housing development by Preservation of Affordable Housing, Inc (POAH). Their mission is to create, preserve and sustain affordable and healthy housing communities that provide economic security and access to opportunity for all people. At Melpet, apartments were designed for low-energy use in townhouse buildings that incorporated airtight and highly insulated envelopes combined with hybrid LUNOS e² ductless heat recovery ventilation systems. The project was designed by Brown Lindquist Fennucio & Raber Architects and Griffith & Vary consulting engineers.
The 27 one-, two-, and three-bedroom apartments each used one or two pairs of through-wall e² heat recovery ventilation fans. They combined these with low flow exhaust ventilation in the bathrooms. The 80 cfm bathroom exhaust fan is controlled by a light switch – so is only used when a bathroom is occupied. This assures that this hybrid Lunos system works as close to the optimal 91% efficiency as possible. Only when the exhaust fan is on will the efficiency of the ventilation drop by around 8 – 12%, but this typically occurs less than 90 minutes per day on average. As a result, the Lunos HRV delivers fresh air continuously for the occupants, while exceeding 75% efficiency with comfortable air temperatures year round.
The one or two pairs of LUNOS e² ductless HRVs are combined in these apartments with ductless mini-splits in the apartments, and some additional back up electric (baseboard) heaters in bathrooms. The project was completed in 2015 and the LUNOS e² system has been running continuously since then. The installation was pre-wired as shown on the left – and the airsealing around the supplied Lunos 6″ installation pipe was completed with ROFLEX 150 gaskets.
Monitoring air quality
We received a request from POAH to check how the indoor air quality was improved by the LUNOS continuous heat recovery ventilation system. In April 2016 we monitored bedrooms in a two-bedroom/one-bath apartment and a one-bedroom/one-bath apartment. The results below show the very positive effects on CO2 levels in the apartments from using heat recovery ventilation.
The graph above shows that when the LUNOS e² is off – at night when the bedroom is occupied (4/11 and 4/12) – the CO2 levels rapidly exceed 1000ppm (the Pettenkofer limit) and even approach the 1400ppm level, which ASHREA 62 considers elevated and if exceeded is a sign of poor air quality. Staying under the Pettenkofer limit is normally recommended for residences as a proxy of good Indoor Air Quality (IAQ). One can see that at both 10CFM and at 15CFM the Pettenkofer limit is only briefly exceeded. Note that the bedroom is occupied every night except for 4/30 and 4/31.
In the two-bedroom unit we monitored (below), the CO2 levels with 15CFM and 10CFM ventilation flow rates lead to good IAQ, and CO2 that barely exceeds 1000ppm. With the system turned off, the results exceed 1000ppm much longer and reach as high as 1400ppm during 4 nights.
For more on Lunos systems, how they work, how they perform, and how they’re installed, we have a variety of videos and posts to discover:
- The Lunos e² Primer
- Introducing the Lunos eGO
- Lunos e²: A Zero Energy Home Solution
- Sizing Lunos e² through-wall ventilation units
- Tighter than expected: time to ventilate without compromise
- No Freezing Means No Defrost Mode for Lunos e² High-Efficiency Ventilation
- Which Switch Is Which? A Guide to Operating Your Lunos