Concerns with an energy upgrade on an old home envelope
I’m planning on residing 3/4 of my house. I will also be installing high density cellulose, and 1.5″ of foam under the new siding. I live in Upstate, NY.
I installed a high efficiency boiler with on demand hot water, in 2010. At that time my blower door test stated that my house was pretty tight. I feel I will probably need a source of supply air. If it could also supply air conditioning in the summer it would be great.
As I stated before I have a boiler (I also use a wood stove), so I don’t have any duct work in the house at present. So I’m looking for ideas on ventilation systems that would supply/exhaust air, and maybe supply air conditioning in the summer. During this house upgrade I will be removing the chimney that used to be used for venting the old boiler and water tank. So I will have a way to run duct work from the basement to the top of the house.
Any ideas would be appreciated. … J.D.
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Replies
John, the Lunos e2 through wall HRV system that we at 475 High Performance Building Supply distribute would be very suitable to cover your ventilation needs, while recovering 90% of the heat of the conditioned air. It will work in the summer as well, by keeping the heat out of your house - but it won't provide any active cooling capcity. You could do that very efficeintly with a separate (ducted) minisplit in the basement or ductless units upstairs. Martin suggest the Lunos e2 as well in his post: Designing a good ventilation system
In case you are interested to get your house even tighter while the siding is off - 475 has a blog series about deep energy retrofits/airsealing that are foam free.
John,
In a retrofit situation, it is usually easier to install a few ductless minisplit units than to try to install a fully ducted cooling system. For more information on ductless minisplits, see this article in the GBA Encyclopedia: Ductless Minisplit Heat Pumps.
It usually makes sense to keep your ventilation ductwork separate from your cooling system. The two best options in your situation are an exhaust ventilation system or a balanced ventilation system (using an HRV or ERV). For more information on these options, see Designing a Good Ventilation System.
Floris suggested using Lunos fans. That is certainly one option; their main drawback is the relatively high cost.
Ducts sized for ventilation systems are tiny compared to those used for air conditioning, and relatively easy to retrofit. Ductless mini-splits are often cheaper/easier/quieter, and definitely more efficient.
If installing mini-splits for cooling it's worth the modest upcharge for versions that do both heating and cooling, especially if your boiler is fired with propane or oil. Even in climate-zone 6 parts of upstate NY there are versions that will still operate at your 99% outside design temp. In most locations in NY heating with mini-splits costs less than half the cost of heating with oil. Heat pumps in general can play a large part in getting the region off the heating oil habit, even when they're not big enough to be a total solution. See:
http://www.efficiencymaine.com/wp-content/uploads/2012/04/EMT_Energy-Efficient-Heating-Options-Report_2013_4_8.pdf
http://www.rmi.org/cms/Download.aspx?id=10410&file=2013-05_HeatPumps.pdf
The Lunos e2 sounds good on paper, particularly for retrofits, but I just couldn't bring myself to buy any right now because:
1. I can't find anyone relating their experience with the units, except for one "testimonial" from a user in Maine. I would want to hear the details of several experiences with the units in humid or mixed-humid climates.
2. I don't believe the price should be any where near as high as I've seen.