Q&A: What would you do?

When my wife Debbie and I met with Point One Architects for the first time to talk with them about our home building project, we already had an idea of some features that we want to include in this new home. This may be our retirement home, so we want our master bedroom to be on the first floor, with a nice view of the mature forest that will be the backdrop to our home.

We want to include energy efficient HVAC and electrical systems, a tight building envelope and photo-voltaic solar panels on the roof. I still need to work out what kind of insulation we’ll be using and a lot of other details about the home’s construction, so I’d like to put this Q&A out there and get some advice from you about what you think would be good features for our new home.

Please comment below and let us know! So far, your emails and comments have provided us with some useful information, and can be a learning experience for everyone.


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  • When you build a home that is super-insulated and airtight (e.g. Passive House standard), there are some considerations that are counter-intuitive. One is that you will need to find a very small heating system. In Connecticut a Passive House can be comfortable with an air source ducted or ductless mini-split heat pump with air distribution to one central point on each floor. With 12 inch thick double-stud R-40 walls and triple glazed windows there is no need for heat terminals under all windows as we have been doing for over 100 years. This is much less expensive than a ground source heat pump and also provides summer dehumidification and cooling.
    Domestic hot water will require much more heat than heating the home will (it is the reason most conventional homes have 100,000 Btu boilers to be able to make 3 gpm of hot water). Solar PV panels and a hybrid heat pump water heater are probably the cheapest way to make the needed domestic hot water, if you have a utility space you can pump heat out of to put into the water. It will double as a “cold room”. Another option might be a solar thermal heater, oversized to allow you to use some of its heat output for a heating fan-coil unit. But you will be dependent on your direct resistance backup heating elements during a long string of cloudy days. And solar thermal systems tend to very expensive compared to Solar electric systems.
    Greg C commented about balanced airflow (in/out) and he is right that a conventional dryer would be acting like a large exhaust fan with no make-up air. Wood stoves are similar in this respect. For the dryer, why not consider Whirlpool’s prize-winning, Energy Star heat pump dryer, that uses a heat pump to dehumidify the circulating air stream and uses the condenser heat to heat the air stream. It does not have ANY exhaust.
  • Dave, remember the HRV takes out as much air as it brings in so the tighter the envelop the more you will need a fresh air make up. When the temps drop here (-40) we don’t run the HRV because it can drop temps in the house and forces the boiler to run more. If you are going to run a boiler section it away from any heated space and make sure it has a fresh air intake. A wood stove needs air and several manufactures of pipe make double walled pipe with a fresh air intake on the pipe. I wish I had seen this before we put our wood stove in. Dryers pull quite a bit of air to do their job, since it is conditioned air the structure will need make up air. Controlling where the make up enters is always difficult. We placed our fresh air intake in the pantry. It was a little cooler in the winter, since it was essentially a none living space this didn’t matter. It is now a little cooler with the wood stove pulling fresh air through it.

    Hope this helps
  • Greg, thank you for sharing your personal experience and application information. I am being very thorough to minimize air infiltration and moisture control layers with building envelope and had planned to use an HVR for fresh air makeup. Your insights are very helpful!
  • Hi Dave,

    My wife and I built a few years ago and had to consider extreme cold as the main factor. Our walls are 6 inch thick with rigid foam. When I build again I will definitely do it differently. 8 inch thick walls with staggered studs, blow in insulation mixed with glue (keeps from compressing), vapor barrier over this structure, and a 2X4 skeleton structure on the inside of all exterior walls. With this type of build the vapor barrier will not get punctured when the kids or wife hangs pictures and miss studs. With the blow in insulation/glue method the excess insulation is removed and plumbed with the studs. The insulation that is scrapped off will be thrown back into the hopper so waste is greatly reduced over foam insulation. Electrical and plumbing can be run through the skeleton so the vapor barrier is safe. Most moisture and heat loss is due to the envelope being compromised. Moisture gets into the insulation and causes matting/compression. Putting the skeleton on the interior of exterior walls keeps the vapor barrier intact. Cost may be a little more up front, but savings in heating/cooling will make up for it.

    While radiant floor heat works great for tiles, it is not so great with hardwood or carpeted floors. In our bathrooms we have tile, but the rest of the house has engineered hardwood floors (AKA plywood with a 1/8" hardwood veneer). I think there are better options for heating especially if you live somewhere that gets extremely cold (-40 here). I think a separate grey water system for waste water would provide good savings. Showers and sinks could run into a separate system that would be used to water gardens , flowers or lawn. Once again cost will be more, but the savings down the road would be nice. Works better if you have a septic system.

    A few other things to consider HRV (heat recovery ventilation), fresh air intake for dryer and furnace. A single remote ventilation fan for the bathrooms (easy maintenance). With houses getting tighter and tighter fresh air is very important especially during the winter months. HRV also removes excess moisture from air and filters fresh air coming in.

    Hope some of this helps.
  • Hi Dave,

    Radiant heating and even some radiant cooling would be great for comfort levels in the home. I like the fact that the architect is planning for maximum solar exposure for some passive heating. A water to water heat pump withe a hot water generator will provide all of your hydronic and forced air needs at a fraction of the energy cost of other HVAC systems.

    The Hot Water Generator feature available on many geothermal heat pumps works well during summer and winter, and helps to keep combustion heating out of the picture, reducing the CO2 emissions foot-print.