BDC Presents: Peter Rumsey - Shared screen with speaker view
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Peter we might as well mention the IAQ impacts of burning gas indoors too.
Is this intended to be an intro webinar?
Is this true that it is more expensive to operated if one has solar on their roof?
Energy efficiency isn’t inherently cheaper than renewable generation. Each has a cost curve. WE are simply at a different place in the cost curve with efficiency than with renewable generation.
Robert, I find in Calif that my rooftop solar costs only 7 cents/kWh and about 10 of those kWh put into a heat pump provide as much heat as a therm of gas that costs $1.40. Sol solar plus HP is half the cost of gas furnace operation.
Does anyone have real-world VRF efficiency measured data? We have one project that appears to consume way more than expected, and we want to see if others see a similar trend.
@ Robert: the graph is if you buy all you electricity from the grid. Having PV will lower the amount of kWh you need to buy from the grid, hence lowering your utility cost.
is cold climate PTAC heat pump available on the market?
VRF uses considerably more refrigerant than traditional packaged heat pumps. The environmental impact of this large amount of refrigerant in a system seems to counter to efforts to sustainably electrify buildings. Curious what thoughts are on this?
The Stanford facility was originally constructed as a co-generation plant with an enormous chilled water loop. Are you are saying they have updated the co-generation technology to a newer generation of equipment that is more efficient and less carbon based?
Peter you and I have done all-electric for new construction. What's the solution for all the existing building stock in the US which is using gas? Electric resistance is less challenging if you have the available power but finding the air-source or water-source for heat to serve a heat pump isn't often there to tie into or line sets couldn't reach the available roof. Or if the existing systems uses 180F HHWS, that high grade is often an obstacle for HPs. Replacing an entire heating system for something based on 140F supply would be a bigger lift and will make decarbonizing more challenging.
@Rona, yes, Stanford abandoned the old 1980’s gas fired cogen system and built a whole new central energy facility (CEF) and new chilled water and hot water loops out to hundreds of buildings.
Here's a good Stanford CEF case study: https://sustainable.stanford.edu/sites/default/files/ZGF_Stanford_CEF.pdf
Is there a report summarizing the calculation of the GHG impacts of a heat pump if all the refrigerant leaked?
I believe Caltech has done something similar with their campus
CO2 dhw heaters are commercially available?
Small ones: see Sanden
@ Karen, that would be a good report. My calculations for my HPWH were that it would cause about a 1 year setback in my COe2 savings (e.g. if all refrigerant were leaked at the end it would re-pollute the last year’s GHG savings. This is sensitive to recognizing the leakage problem of methane vs. leakage of refrigerant.
I always love the discussion that happens on these presentations!
@ karen, so one of my findings is waiting a year for better refrigerants is not good for the climate.
Karen, I have poked at that question a little bit, with some back of the envelope calculations. My conclusions basically line up with Tom's
@Tom, thank you! It would be great to have a report to share and cite on this.
don't boo. vote. the vacated SNAP 20 and 21 rulings mean a coalition of ~25 states in the US climate alliance is now trying to enact the HFC phaseouts the federal govt isn't.
I found that a HPWH with conventional refrigerant (R-410a, GWP of 2,086) might have about a 60% or so lifetime GHG savings vs gas with 3.5% leakage per year, or if it all leaked out somehow the lifetime savings would be 56%.
Dom Lempereur, towards your question about PTHP low temperature units most of the affordable ones switch to resistance or hydronic heating below 40F, but there must be ones that operate as low as the mini-splits which is down below zero F
Here is an ever growing slide deck of all electric buildings. If you have projects to add send them my way. Many thanks! https://drive.google.com/file/d/1lyMrHVXgXgKvtJgi831UGs_U0bQ74pbA/view?usp=sharing
Peter, In the SJ Bank of Italy retrofit, will the coolth from the rooftop reheat loop heat pump “boiler” be captured?
Kevin Leecaster: thanks. I have been looking for those for a few years now. If anyone know manufacturers, please send my way...
Who has experience with 2019 CBECC-com on all-electric? Bugs? Limitations? We helped on the UCSF project and it was a nightmare.
@Tom and Alexi: Please forward your lifecycle analyses on refrigerant impacts to email@example.com. Thank you.
Just found this low temp PTHP, -5F, http://www.ice-air.com/wp-content/uploads/ICE6084-PTHP-SPHP-Brochure.pdf, but there are many manufacturers of them. I am sure your HVAC supplier can hook you up quickly.
Great message here! Continues the Mazaria admonishment "Architects Pollute" from his article in the 70s I think. Can be a change message
I used to do building envelope air leakage testing on older multi-family units with PTACs and they had high leakage. It sounds like that issue has been solved?
My question was really targeted to commercial building stock.
Yes, replacing existing equipment would mean pre-planning to install infrastructure prior to the equipment dying. No one wants to go without heat or hot water. So we have to act well before the equipment dies unexpectedly to have electrical systems permitted and installed in advance. Utilities or cities need to figure out how to electrify buildings. It'll be a challenge.
One refrigerant strategy is: Never buy a singe direction air conditioner. Always buy a two directional heat pump. Maybe incentives and regulations would help here.
Do you have links to COP vs Outside Air Temperature for Residential HP down to -14 °F?
For large existing commercial buildings how feasible is it to convert the cooling system to a heat recovery chiller or other solution to provide electric heat & cooling
Peter, do you have any idea of the prospects for combination units that provide heat both for space and water? What are the key barriers keeping us from having something along the lines of Energiesprong "all-in-one" applications here in the US?
check out NEEP's cold climate ASHP product list...https://neep-ashp-prod.herokuapp.com/#!/ some products provide performance data below 5F
@Mark, Here’s a link where you can see cold temperature COPs for residential HPs. https://ashp.neep.org/#!/product_list/
For average single family dwelling owner with gas hot water heater without solar panels, is there cost savings by changing to heat pump hot water system (what is the selling talking point for owner to change)?
What is this term that was just mentioned? “Energy strong”?
NYSERDA (NY State) is testing the energie sprong approach on 6 buildings, I believe.
NYSERDA is killing it. as usual! :)
E3 and RMI have home electrification studies. Navigant did a competing one specifically for CBIA.
The HPWH is only more expensive when you ignore rebates! I personally just got a HPWH for $225, delivered, after the utility rebate! Installed it myself in an afternoon.
Kyoto. Going from gas furnace plus electric Air conditioner to just a two way heat pump saves equipment and makes you comfy and improves your climate legacy.
Okay does anyone have a last burning question they just HAVE to have an answer to? We're about out of time!
Peter, great presentation! Thanks so much! Richard
Some free all electric construction guides can be downloaded here: http://www.redwoodenergy.tech/research/
Very informative, thank you. It will be helpful to have simpler cost-benefit presentation materials for owners of all sizes to help with decision-making because the technical details can be confusing.
Buildings with no A/C could install a heat pump instead without raising cost much.
@Kyoko Hibino: I retrofitted my single family home in SF Bay Area 10 months ago with a Sanden CO2 hot water ($8k installed cost). If I replaced with $1k nat gas, it's going to be hard to close a $7k gap. A Rheem heat pump install = $4500.
Great presentation Peter, thanks. lots of great slides