Replies

1. 
   DavidDrake | Jul 16, 2022 11:49pm | #1

   Interesting. The other Washington (State) has a somewhat similar provision regarding natural gas in the proposed new residential energy code. There's been a lot of push-back, mostly from home builder associations, but also from some utility companies.

   Pretty sure WA State's electrical generation mix is majority renewable: mostly hydro, but also an increasing amount of wind. So encouraging consumers to move away from NG and toward all-electric makes sense. Is the same true for DC?

2. Expert Member
   BILL WICHERS | Jul 17, 2022 12:14am | #2

   DC is part of PJM, so roughly 1/3 nuclear, 1/4 coal, and most of the rest is natural gas. The actual mix varies throughout the day, but is usually somewhat close to those fractions. You can see what their mix is at any given time on their real time data page here: https://www.pjm.com/markets-and-operations.aspx

   I can see how this could work for residential properties (although I really don’t think it’s a particularly good idea at this time), but I don’t see how it can work for larger commercial buildings that typically use a large central boiler. I’m not aware of any large scale (million+ BTU) heat pump boilers or air handlers. Does anyone know if any such units exist at this time?

   I’m curious about the “net-zero ready” part. I’ll have to read through and see what they’re looking for for that part. Maybe significantly better insulation than usual? Better insulating and better air sealing are probably the low hanging fruit in terms of energy efficiency, at least for new construction. I’d really like to see some concern for cost of construction with these kinds of proposals so that we don’t go overboard and end up pricing people out of homes.

   Bill

1. Expert Member
   Akos | Jul 17, 2022 09:54am | #3

   Possible if there is water around:

   https://buildipedia.com/aec-pros/engineering-news/torontos-deep-lake-water-cooling-system

   River water will be warmer but can make for a decent heat dump/source for a water to water heat pump.

1. Expert Member
   BILL WICHERS | Jul 17, 2022 11:02am | #4

   That’s for district cooling though. I’ve worked with lots of cooling systems. What I haven’t seen is a large scale heating system. I don’t see any reason why such a system couldn’t be built, I’ve just never seen one, and I haven’t seen any advertised, either. All it would be is a chiller in reverse, like a heat pump with water on both sides instead of air. It just looks like no one makes such a beast.

   Bill

2. Expert Member
   NICK KEENAN | Jul 17, 2022 05:41pm | #5

   I think part of the idea is to push the development of the technology. The DC government is also required to stop installing gas appliances in its own buildings starting in 2025.

   The obvious answer would be, "can't you run the cooling system in reverse?" But thinking of how cooling towers on big buildings work, it doesn't seem like something you could retrofit easily to heating.

   There's a lot of geothermal going on. I know the University of the District of Columbia just dug up their football stadium to put a bunch of wells in to provide geothermal to the campus. That seems to be the way people lean when the system gets too big for an air source heat pump.

3. 
   paul_wiedefeld | Jul 17, 2022 09:54pm | #6

   Pretty minor change for the city, I imagine heat pumps have a high market share among new condo buildings, which also have low emissions to begin with.