Of Insulation & HVAC
One of our goals with this project has been to construct the most energy efficient and eco-friendly building envelope possible. This has required that we pay close attention to the various insulation values and invest in the most efficient HVAC system we can afford. Regarding the insulation, it’s looking like we’ll have the following:
- Basement Walls: R-22.4+ (ICF)
- Headers: R-36.4 (2” exterior rigid + 4” sprayfoam)
- Exterior Walls: R-32 (2” exterior rigid + interior Roxul)
- Roof: R-40 (6” sprayfoam)
- Overhangs & Garage Ceiling: R-62 (9.5” sprayfoam)
- Under Garage: R-10 (2” rigid)
The R-value of the overhangs and garage ceiling seems like overkill to me, however our mechanical engineer insists that we completely fill the void to eliminate air movement and reduce the potential for mould buildup. It’s obviously hard to argue with that. We had originally planned on using a closed-cell sprayfoam everywhere, however that proved to be far too expensive. As a result, we’ve decided to use 2” rigid panels on the exterior, plus Roxul on the interior.
We also need to make some decisions in regards to the actual equipment. We had originally considered geothermal as a possible solution, however it was incredibly cost-prohibitive when we ran the numbers (cheap to run, expensive as hell to install). As a result, we decided to go with something a little more traditional and we’re currently leaning towards the Carrier family. Specifically, we’re considering the following:
- Infinity Zone Control
- Infinity 96 Gas Furnace
- Infinity Series Heat Pump
- Performance Heat Recovery Ventilator
- Performance Series Humidifier
- Infinity Air Purifier
I’m not 100% sure if we really need an air purifier, but it would be an obvious plus. I’m also unsure about the heat pump. As I’ve mentioned before, a heat pump works as both an air conditioner and a heater. However, it only operates as a heater in “cool” temperatures which means it’s unusable when the temperature drops below -3°C. Given the Canadian temperatures, I’m unsure if the heat pump really makes sense or if we’d be better off relying solely on the furnace for heating and a more efficient air conditioner for cooling?
Similarly, while I’m digging the Carrier products, our HVAC installer is recommending KeepRite instead. Everything I’ve read online suggests that they’re decent (and cheaper), but not as good as the Carrier offering. I’m not exactly looking for the best of the best, but I really like what the Infinity line have to offer. In particular, the control unit supports up to 8 zones in the house and can independently control every facet of the system (heating, cooling, humidity, fan speed, ventilation, etc.) Obviously this requires that each unit be part of the Infinity line, but it’ll mean the system is also working as efficiently as possible. They may be cheaper, but I can’t imagine the KeepRite products are really comparable in this regard?
Photo via Flickr user targophoto.com>
Post Tags: HVAC, insulation
Hi
— posted on November 27, 2008what is the R value of your windows and doors
Our windows are Marvin Integrity and based on the supplied documentation, it appears that the average R-Value of the windows is somewhere around R-3. As for the door… I’m not sure yet, as we haven’t picked one yet. Aesthetically, we’re leaning towards a solid wood door (which will have an R-Value of 3.7), but an insulated metal door would provide the greatest R-Value (around 15).
Come to think of it, is there an insulated wood door? I think we need to look into that…
— posted on November 27, 2008Hi,
When we built our home, it was suggested we get a two zone system. We decided the price was too great. I am glad we did not do it as the basement is the warmest part of our home (around 2000 square foot bungalow). We have finished the basement and insulated the walls very well. We have large windows upstairs which make it cooler but comfortable compared with the basement where we watch TV in comfort. We keep our temperature at 69 during the day and 65-66 at night. All rooms in the basement have cold air returns as well which really helps. We also have ahigh efficiency Carrier furnace. Look at whether you really need the two zone system. Is it worth it after you spend so much insulating the basement?
— posted on November 27, 2008Jeremy,
If your mechanical engineer hasn’t already mentioned it, running one of the more extensive calcs like “Manual J” would be good for properly sizing you equipment. With those great R-values, you should be able to significantly reduce what would typically be installed in a house of this size.
Actually, are you sure the roof value is correct? Most of your heat wants to get out at the roof – local codes in the states want an R-38 minimum…
— posted on November 30, 2008I must admit, I’m not too sure what he used to run the calculations. Our architect insists he does a good job, so I’ve simply followed their recommendation.
He did suggest that we could get away with a “lesser” system, but I’m interested in the “whole package” management that the Infinity system provides. It’ll obviously cost a little more, but I think the overall comfort of the home will be that much better because of it.
As for the roof values, they are indeed correct. We had originally thought about going above code (which is R-38 here as well), and come to think of it… we might actually up that a bit. We haven’t made the final decisions on that (and thanks for pointing it out!)
— posted on December 1, 2008Jeremy, If you are still able to, I would really reccomend an HRV for your HVAC systems. I say this because you were concerned about your intake not performing well in sub-zero temperatures and HRVs work very well to recycle 60-70% of your thermal energy from your indoor environment. It translates to cost savings in energy bills of about 20-30%, summer and winter.
— posted on December 5, 2008Hi Tim – we’re actually going to be getting one (it was listed above… “Performance Heat Recovery Ventilator”)!
— posted on December 5, 2008Hey Jeremy,
Regarding the air source heat pumps, there is another all climate heat pump made by Mitsubishi that you may want to consider. It’s called the Zuba Central:
http://www.mitsubishielectric......re_ENG.pdf
claims to be efficient down to -30C outdoor ambient temp with a COP range of 1.4 to 3.19. 15 seer cooling and 9.4 HSPF heating. if it works as advertised should outperform gas furnaces with added bonus of providing cooling and heating all-in-one.
there was that other all climate heat pump by hallowell, but i figure with mitsubishi you get a more established name and i’ve read great things about their mr. slim ductless split systems.
— posted on January 23, 2009