Heads up to those of @reef-full that were not at today’s plenary, and in particular @RichardB, @mariaAM, @Hannah, @Jeroen and @joannes: we consented to a proposal on the setup of an energy community. One of the components of this proposal was that we agree to not go for geothermal at this stage. The decision needs to be made, because installing geothermal heat pumps implies that we need to allocate 20 m2 in the basement. When we apply for the permit, we need to include a full plan of the basement, so the decision needs to be made now.
What I mean by "letting go of geothermal at this stage is:
Geothermal is off the table for the first 10-15 years. We can reconsider once the air-source heat pumps come up for replacement.
The decision on the plans of the basement could, in principle, be modified later by introducing a rectificatif to the building permit application – so, the decision is in principle reversible.
As an add-on to the proposal, we agreed to ask the architects to make the building “geothermal ready” (unless it is horribly expensive). We believe it is as simple as having a pipe in the basement that we could, in the future, use to connect the basement (where the heat pump would be) to the deep hole in the ground that we could drill in the future.
You can still object in the next 48 hours. Also, I would like to get an idea of where you stand on this because it is the households with a strong commitment to sustainability and some financial means that, in the terms of the proposal, can bankroll the energy community. Could you have
Hello Alberto, the proposal is fine by me (us), well done by everyone involved!
We support the idea to found an energy community, whether and to what extend we’ll be able to contribute to solar panels and batteries will depend on the final pricing of the Reef, as such I think once we have an Entrepreneur Général, we’ll know more.
As I unfortunately couldn’t be present at today’s plenary, I still wanted to take the opportunity to explain one reason as to why I’m a lesser fan of the air heat pump solution, and that is because I perceive they aggravate the cross-subsidisation from bigger to smaller units: We had discussed in the past that smaller units add proportionally more to construction costs than larger units due them requiring proportionally more ressources , and here we’re dealing with a cost position that is almost entirely made up of costs per unit (sth like 10k?), but then divided by our distribution key, where as a result larger units contribute more due to the larger space they occupy. When we consented to our valuation key, your argument against the inclusion of a size factor was that the finition will absorp some of these cost effects. I wonder then whether we shouldn’t discuss to move heat pumps from casco to finition?
The way I read your post I understand you are implying that you are not a fan of air-source heat pumps because they aggravate the cross-subsidisation from bigger to smaller units. Do I understand that correctly?
If yes, can you please explain to me how that would be different for geothermal heat pumps? This is not fully clear to me.
Yes your understanding is correct and in this context the geothermal solution, albeit being more expensive in absolute terms, has a positive side to it as it’s cost structure is to a larger extend of a fixed kind and to a lesser extend in variation of the number of households. Now my intention is not to re-open the discussion on what kind of heat pumps we should install or on the components of our valuation key - I‘m more cautious on the feedback we got on the pricing of the bigger units from interested parties. Also, I reckon the cahier de charges will at some point allow to follow up how much a unit actually costs to build, a large difference with our price tag can then lead to issues with mortgages as banks are not likely to base the estimated value of a unit on our model but more on the cahier de charges.
Thank you for the proposal @Alberto! We are ok to let go on geothermal heat pumps. I think my major concern was that I have always seen geothermal heat pumps as the even more sustainable option than the air-source heat pumps. And I got the idea that we were choosing for air-source heat pumps out of mere economical reasons. It made me think of offsetting CO2 emissions (although probably the comparison doesn’t go well): you book an airplane, you pay for CO2 offsetting as this is economically more interesting, although the better option would have been to pay more for a train and contribute drastically less to CO2 emissions . As we are not opposing to the proposal, maybe this is something we can discuss further another time at the occasion of a plenary meeting or a FM dinner. We are in any case fan of the energy community. Thanks for the work you have put in, interesting stuff!
Aha, got it. No, in my understanding both AS and GT heat pumps use electricity from the grid. How green that is depends on the energy mix of the grid itself. GT is more efficient, but not vastly so, only about 30%. So moving from AS to GT is not like moving from the plane to the train: you are still on the plane, but you moved from economy+ to economy class.
On the other hand, a serious solar array means we can produce locally 2-3,000 kWh per year per unit. This is energy that is green for sure, because it comes from our own roof and not from the grid. Again, we are moving to economy class – still on the plane, but we are doing it a greatly reduced cost.
Where we are moving to the train from the plane is with good insulation. Instead of 15,000 kWh per year per unit (and it’s methane!) we reduce our heating-induced consumption to something like 2-3,000 (and it’s electricity).
Just as a short update: we talked to the architects and Walk yesterday, and it seems that it will be possible to make the building “geothermal ready” for when we’ll need to replace our aerothermic heat pumps in 15 years. What I understand from it, is that it means that they will pay attention to leaving space for drilling (in the future) when placing the rainwater tanks, and also making sure there are entry points for the pipes at the bottom of the buildings. All this should be feasible, and will be taken into account.
. As we are not opposing to the proposal, maybe this is something we can discuss further another time at the occasion of a plenary meeting or a FM dinner. We are in any case fan of the energy community. Thanks for the work you have put in, interesting stuff!