Excellent. Thank you for sharing. The passive components of the envelope look great. However, the mechanical systems really look like they need a lot of work. Lower temperature heat networks are so important in cold climates because they can be provided with ground source cold reservoirs at 5-10degress C, and then supplemented with ~100hrs of thermal energy storage in a multifamiliar water tanks from a central hub would allow you to interact with the grid using exclusively off-peak electrical energy. Discounts of more than 60% per kwh of electricity can be negotiated if that were the case, and you'd be drawing from higher quality sources to improve COPs up to 5 even in the depths of winter, with averages near 10. Finally, a phased approach to replace the basement slab to add insulation below grade would be nice, but also a hydronic underfloor heating system will give you a very nice heat exchanger to use lower grade heat - further improving COPs.
@retrofitcanada86503 жыл бұрын
Thanks for the comment, Frank! We agree that ground source heat pumps make a lot of sense. Well designed ground source heat pumps (geothermal heating systems) can deliver 4 units of heat energy for each unit of electricity. The air source heat pumps we are using at Sundance are expected to deliver an average over the heating season of 2 units heat for each unit electricity, but in really cold weather, it drops to 1 to 1 require larger electrical capacity. Ground source heat pumps were not a good option in this case because of all of the trenching and drilling that would have been required - and the higher cost. We would have needed 60 to 80 boreholes and a mesh of trenches to connect them plus a pumping station and some way of distributing the fluid to each unit. We are working on a (possibly harebrained) scheme to do directional drilling from a central location that could make this a lot less disruptive. If that works, geothermal might make sense for the next one. Replacing the basement floors and using in-floor distribution would have been far too expensive to be practical. We could even afford to insulate them on top on a cost-effective basis. Just too much money for the available savings.
@FrankReif3 жыл бұрын
@@retrofitcanada8650 Thanks for your detailed reply. It's tricky to get a good, stable, low capx, source at the moment. I guess you're not lucky enough to have a water source or aquifer nearby on the site. Shame, boreholes are not more common to drive down price. Soon, low-interest financing will be available for this, so the price won't even mater that much. It could be part of a phased development once we get up to speed with how inevitable all this stuff is. I didn't make the point about storage very well. The key is to be able to load shift outside peak hours and get variable tariffs. It reduces costs/kwh of electrical energy but also reduces the connection costs because your peak load will be lower since the dwellings will be provided with avg 40 deg C heat during peak heating loads - due to very high COPs. I hope that makes more sense. A central water tank, holding a few m3/dwelling, would allow your air source heat pumps to operate all day using below peak rates (with boreholes/water sources you get even lower nighttime rates because you don't need to worry about ambient nighttime air temps). The cost/m3 becomes incredibly cheap and efficient when you make these tanks larger because of the surface to volumes. So if the space allows for it, go for 100hrs of storage to make use of low cost solar and wind on the grid. You can even get paid to balance the phase during curtailed energy! There are even dual stage heat pumps that increase the efficiency up to 60 deg C without burning out your refrigerant. Say an ambient -20 air source to 20 deg C, followed by a water to water one from 20-60 deg C. You can't do these sorts of things on a uni familiar basis. I wish we would stop with rooftop solar. It's ugly and expensive. Grid scale and wind is always going to be better, and we will eventually stop with small scale installs. Electricity is cheap, it's just not cheap all the time! Hence the storage. All the dwelling would need a heat meter to roughly gauge the amount and quality of the heat, as well as their own small water source HP to boost temps for the radiators and DHW. These hybrid systems are becoming common practice in Sweden and Finland.