Hi @Lee
I have started a document with all the pros and cons of both type of heat pumps (TB/avant projet/Heat pumps)
I don’t know if you have seen this, but the IBGE facilitator had already given some pros and cons of the system => you can find this back in the mail exchange (proton mailbox, folder IBGE): replys of March 20 th and March 26th
I’ve contacted the facilitator again last night, asking more about possible pros and cons…
@Lee : if you would be contacting the architects tomorrow, could you ask them a question concerning this topic?
I would like to know the space they occupy
I guess for the geothermal one, there is 0 m2 required in the apartment (but space required in the common technical room).
How much space is needed in the common technical room for the geothermal heat pump: a full 20 m2?
How much space (m2) needed in the technical space of the apartment, in the case of air source heat pump?
To double check: does the geothermal one needs space on the roof (or in the garden)? Online I read that no space on the roof is needed , i the comparaison table of Walk i see there is some space needed
Extra info from Wa.L.K. on this topic: TB/avant projet/bureau détudes/WALK - PEB & Heat pumps.
I integrated this in the document with pro’s and cons, but I don’t understand some things.
@Lee : feel free to modify and/or change the layout… I have tried to look up the life cycle cost via chatGPT but it gives contradictory information with the other info…
I will work on in it this afternoon and ping you when I’m ready.
I have created a 2-page summary note to explain the highlights and to look at the financial aspects.
Saved in Team Building > Avant-projet > Heat pumps: Login – Nextcloud
Overall, even when taking into account increasing electricity prices, it doesn’t look super good (though certainly better than the 137 years 
).
The key point on which I’d like to get feedback at the plenary tomorrow is the last part, on exploring the options to finance it on a voluntary basis. If there is not much enthusiasm for that, we should probably close the issue.
hi, based on what I learned from the meeting this morning. I asked Google Gemini (Advanced with Deep Seek Pro 2.5) to produce a report, using the following prompt.
|-|Apartment complex with 22 living units in three separate buildings|
|-|A typical apartment would have 2 people living there.|
|-|There are a few communal spaces, taking upon the space of 3 apartments
|-|The three roofs are covered by a total of 50 solar average size solar panels|
|-|In Brussels, Belgium|
|-|A battery will be installed
|-|About 7 apartments run the risk of overheating in the summer|
|-|Newly built passive housing (to be delivered in 2028)|
|-|Inside temp to be kept between 20 and 24 celsius|
|-|What would be the optimal battery capacity?|
|-|What are the pros and cons of ASHP or GSHP| [A=air G=geo sourced heat pump]
|-|After how many years would the GSHP investment offer a return?|
|-|How do the different choices affect the energy independence|
Here’s the 30-page report, citing 70 sources.
Of course, I have some of the numbers in the prompt wrong, but this is easily corrected by running the prompt again. We could add other items to the prompt.
Even if the report contains inaccuracies (and I cannot tell), it will help in conducting a conversation with the technical experts.
Look mom, no hands! 
@joannes, for your reference, here’s the links where you find the detailed documents:
@els and @joannes I saved the meeting notes in the document with meeting notes with the architects (Login – Nextcloud). Feel free to add your own notes and corrections.
@lee and @els, here my draft proposal for making ground-sourced heat pumps affordable for all.
May I ask you to do a peer review? I’m available tomorrow to discuss and amend, so can publish Friday late afternoon.
Thanks a lot Joannes!
I inserted some small comments and corrections. Feel free to do what it as you see fit.
As a general observation: even without numbers, I will most likely not sign up as an investor for such an Energy Performance Contract (EPC) with Shared Savings.
So if you agree I’m going to add a second proposal, in which everybody chooses the heat pump system of their choice.
All in all I’m afraid however that it is just not possible, and that it may be preferable to save our resources to possibly set up an EPC for a battery in the future. Let’s see.
Hello @joannes, @reef-coordination and @reef-buildfin,
I have drafted a short proposal on leaving everybody the choice when it comes to heat pumps. Would anybody have the time for a short peer review?
Saved in the proposals folder: Login – Nextcloud
Hi Lee, just went through the proposal and added a few comments for clarity , other than that looks all good to me - Thank you!
Thanks Richard! I replied to your comments in the document.
@reeflings Here’s the proposal for the energy system. Login – Nextcloud. Who has a moment for review?
Hi @joannes,
Thanks a lot for this proposal and the time you put into it. I really appreciate it.
I have a question for clarification, which is one a quote I believe to have seen in the Protonmail, for 20 geothermal heat pumps, which - if I am not mistaken (which is of course well possible) - was only 20k away from the estimate we got from Walk. Can you confirm this, and if yes, save the document on Nextcloud and add a reference to the proposal?
Another question would be on the scope of the service request to the IdeaLists. Am I wrong in assuming that detailed advice on the financials of an energy community are available for free, from one or the other government instance (ping @alberto)? If that would be the case, can it be an option to reduce the request to just a ROI and TCO estimation of air-source vs geothermal heat pumps?
An a final question, which I’ll ask Walk and the architects next week, is whether such an estimate is not foreseen in the contract that we have with them anyway, just at a later stage.
@Lee I’ll look into this early next week, well before the plenary of the 25th, which, BTW, I can only attend remotely.