Ben of the cohousing Biotope replied (mail is in the proton mailbox). He gave a link to the fiches they made as energy ambassadors, and he also gave his experience (with a common installation) and his advice as he is not only a person living in the cohousing, but is a professional giving advice about heat pumps.
they are really pleased with their choice and found it worth the money (but got financial support of 100.000 being energy ambassadors).
Like your (hannah’s) experience, they really like the cooling via the floor heating system, without any noise, and for free (passive cooling). In one of the fiches they explain that you cannot go below a certain temperature (‘dauwpunt’), otherwise you have this condensation issue the architects talked about. But it still brings the temperature low enough.
he indicates you need to be with 15 units to go for a common geothermal installation, otherwise go for individual installations (financial reason). As I don’t think there would be 15 families participating, I think this means that the prices WaLK gave are an underestimation of the price as they counted on a minimal amount of people to sign in on geothermal.
Going then for individual geothermal heat pumps loses the advantage of the common system in the way that a common system is better at buffering energy than individual systems
He indicates that if we would go for a common system, because of the configuration of our site/buildings (3 buildings, lots of garden in between), it would be a technical challenge that goes together with a lot of costs. (I also read between the lines ‘extra risks’). I don’t know if that completely disappears if you go for individual heat pumps.
In one of the fiches, as a down side, they mention there needs to be sufficient know-how to follow the process or to get a maintenance contract with a specialised firm (which also translates into a certain cost).
on the plus side, they obtain a good yield of 1 unit of electricity producing 5 units of warmth.
For me personally - even though the passive cooling via the floor heating system - sounds great, mainly the price weighs too heavy (and I think this price might still be underestimated by Walk as you would probably better go for an individual system).
The link to the fiches, which not only talk about the geothermal pumps, but also about overheating, ventilation,… and contains quite some data they measured themselves : Biotope als Energieambassadeur – Biotope
I also would like to ask Walk some more questions about cooling, once we go more in detail of these techniques.
Ignoring the sustainability aspect of geothermal pumps (by which I don’t claim this isn’t an important one),
Floor heating/cooling
I read that cooling via the floor heating system is perfectly possible in combination with an air-water heatpump, equally respecting a minimum temperature of 16-18 degrees of the cooling fluid to avoid condensation.
The disadvantage here is that we will be having active cooling (= consuming electricity) in comparaison to the geothermal heat pump where we have passive cooling.
But one of the things Biotope also mentions in their fiches: try to consume energy at times that you produce energy (in case we would have an energy community). Putting 2 tables next to each other, you see that the months were you would need cooling perfectly match with the months where you have the biggest production (and maybe overproduction) of electricity.
graphic of Walk showing the solar production vs energy consumption (in case the complete roof of Obelix would be full of solar panels vs the energy consumption of the people of Obelix only)
Ventilo convectors
As an alternative to radiators and floor heating, as heating systems, Walk talks about ventilor convecteurs in there technical note. They only mention the heating aspect, and nowhere -except for the cooling function of the ventilation at night - do they talk about cooling.
Googling these ventilo convecteurs, I read they – unlike radiators – can not only heat but also can cool, but probably also limited to cooling with water of 16 to 18 degrees in order to avoid condensation problems.
Another advantage is that they are cheaper than floor heating/cooling, but more expensive than radiators.
They are above ground/accessable, like radiators.
In comparaison to floor heating, they heat up/cool down faster. .
A disadvantage is that they make some noise
But as mentionned above, questions to ask to Walk.
I’m not sure I understand the key points of the posts above. What I take from it:
Cooling is also possible with air-to-water heat pumps. It would require extra electricity, but this happens at a moment where you can self-provide through solar panels.
Geothermal is expensive, and possibly risky. Biotope also got a subsidy to which we don’t have access.
As far as I understand geothermal heat pumps also require an environmental permit. I don’t know how much time that would take, and how that would interfere with work on the call for tenders.
I don’t want to stand in the way of course, I’m just trying to understand what is new here, and what would be the questions we would be asking to Walk.
the risky part for a common geothermal installation, linked to the parameters of our project
that if sb still would want to go for geothermal heat pumps (and reopen this discussion), it would probably mean going for an individual installation, not a common
(some) pro’s and con’s between an individual and common geothermal heat pump installation
real data/measurements and prices at the time of their construction (mentionned in the fiches)
Questions for walk (not for now, but later)
contradiction between experience of Hannah/Biotope and what the architects said about limited cooling with heat pumps.
options for cooling as this is not mentionned in their note tehnique. Pro’s/con’s of the different options that can work with air-water heatpump: price, energy consumption, noise level, …
The point of hannah that seemed contradictory with what Francois said and together with the fact that Walk indicated that they were going to take a training on heat pumps, made me assume that they might not know all there is to know about heat pumps
Hence my need for further information/people with an experience a bit similar to our situation.
Hence also the question I asked myself: if you can deduct the price of your cooling system + electricity cost from the price of your geothermal heatpump, won’t this get financially interesting after all?
For me it was not necessarily the goal to bring new elements. The talks with Walk didn’t give me a very satisfactory feeling and Joannes’ attempt to bring more info/clarity with the IdeaLists was stopped because it required quite some money. I now feel relieved with this feedback from Biotope, it also gave an answer to my questions and a better understanding. The goal was to share this, in case somebody else had that same insatisfactory feeling/questions.
I actually appreciate these additional efforts on this topic because Richard and I had divergent opinions, but this is helping me to better digest the pros and cons. The reason I haven’t joined the helping circle is because I wasn’t sure I could dedicate enough time, that’s why I like reading about new info/ data.
