ᐅ Cooling Concept for New Construction – Split Air Conditioning / Air-to-Water Heat Pump Cooling Function / Combination

Created on: 20 Jun 2021 11:49

Hello everyone,

I am currently planning the construction of a single-family house and am still undecided about the cooling concept. I have attached the current floor plan. Regarding the layouts, I also started a thread in the floor planning forum (https://www.hausbau-forum.de/threads/grundrissplanung-und-platzierung-efh-ca-200qm-auf-900qm-Grundstück.39104/page-4#post-505270).

This is a KfW 55 new build (Poroton brick, reinforced concrete ceiling) with an air-to-water heat pump, controlled ventilation system, and blinds/shutters on all windows. The garden side with the large windows faces southwest, the entrance side faces northeast. The office facing the garden definitely needs air conditioning, as it is in constant use with many technical devices generating significant heat. Otherwise, I personally prefer it quite cool; I usually vacation in Scandinavia but definitely not in Greece, Egypt, or similar. In other words, my comfort temperature is significantly lower than most other people’s.

Now I am considering the best way to cool the house (aside from shading, etc.).

Option 1:
Split air conditioning unit in the office

Option 2:
Split air conditioning unit in the office + cooling function of the air-to-water heat pump (about 5,000 EUR extra)

Option 3:
Split air conditioning unit in the office + living/dining/kitchen area

Option 4:
Split air conditioning unit in the office + living/dining/kitchen area + upper floor hallway (probably only above the stairs, supply temperature— not ideal because cool air might directly sink to the ground floor)

Option 5:
Split air conditioning unit in the office + living/dining/kitchen area + child’s room + child’s room + bedroom

Furthermore, I wonder how big the difference is between installing this as part of the new build or retrofitting it later (significantly more expensive if done afterward? Potential issues with KfW 55 standards?).

Also, I am unsure whether to use one split unit per room or a multi-split system. Currently, I have no concrete offers with prices.

Thank you in advance!

Best regards,
Sam

Views:

Modern white villa with carport on the left, entrance facade and green garden.

Modern white single-family house with gable roof, large windows and garden.

Floor plans:

Floor plan of a house: garage on the left, two offices, hallway, WC, open living-dining-kitchen area with dining table.

Floor plan of a house: two children’s rooms, sleeping area with walk-in closet, corridor, utility room, bathrooms and stairs.

Samantheus24 Jun 2021 22:02

#13

Yes, there is a reinforced concrete slab on the ground floor and the upper floor. I had thought that with concrete core activation, you wouldn’t achieve comparable cooling performance? If you still need a split air conditioner for dehumidification, I wonder how it would be cheaper.

I discussed the brine-water heat pump with the construction company, but it doesn’t make sense. Deep drilling is extremely expensive because all companies are fully booked (additional cost around 30,000), surface collectors also come with a hefty extra charge (I think around 15,000), and the heating installer has never worked with trench collectors. I simply don’t want to be the first experimental customer there...

Yes, I also find the extra 5,000 to be extremely high. I can’t really explain why it’s so expensive. But for concrete core activation, wouldn’t I also need the cooling function of the air-water heat pump? Do you know approximately what costs to expect for concrete core activation and how its cooling performance compares? I’m particularly concerned about the south-facing office, which is full of heat-generating equipment, and whether concrete core activation will be sufficient in summer…

kati133725 Jun 2021 00:05

#14

We installed three split air conditioning units: one in the office, one in the living/kitchen area, and one in the hallway for the entire upper floor. This way, we cool the bedrooms by leaving their doors open. You can slightly notice the effect of cold air moving down to the ground floor, but the split units can be adjusted to control the angle and direction of the airflow, which helps a lot.

So far, we are very satisfied with this solution. We usually only run them when we get electricity from the solar panels on the roof, and the house stays comfortably cool.

Dogma25 Jun 2021 07:31

#15

Samantheus schrieb:

I’ve just received an initial quote for a Daikin R32 multi-split outdoor unit and a total of 5 [I]DAIKIN R32 wall-mounted units Comfora[/I] for around €19,000 (including installation). That seems quite high compared to your figures; I will look for alternative offers. Do you generally have good experience with Daikin and are you satisfied?

We also installed a Daikin R32 system, one outdoor unit and five indoor units. It’s been working perfectly for 2 years now 😉
For the indoor units, we chose Emura models.
The price of €19,000 is probably influenced by the pandemic. About 2 years ago, it would have been around €16,000.

Strahleman25 Jun 2021 08:10

#16

Samantheus schrieb:
If anyone can recommend a company in the region, I would really appreciate a tip or a private message.

You’ve got a PM from me. I hope you can read it with fewer posts than required.

Samantheus schrieb:
Yes, it’s a reinforced concrete ceiling on the ground floor and first floor. I thought that with concrete core activation you wouldn’t get comparable cooling capacity? If you still need a split air conditioner for dehumidifying, I wonder how it ends up being cheaper?

The cooling function on our heat pump (Nibe S1155-6 brine-to-water heat pump) would have cost around 3,000 euros — without concrete core activation (CCA).

Samantheus schrieb:
... and the heating engineer has never done horizontal trench collectors before. I just don’t want to be the first experimental customer there...

Depending on how skilled you are and how much you want to study the topic, a horizontal trench collector is actually quite easy to install yourself. We installed one on our property for the first time as well, and thanks to free software (Trenchplanner) it was super simple. Because of COVID-19, only three of us worked on it (an excavator operator who only dug, my father, and I who laid the pipes), and it took almost exactly 8 hours. There is very good planning support in the “pink forum.”

Samantheus schrieb:
Do you have an idea of the cost for CCA and how the cooling capacity compares?

Of course, it depends on the surface area to be covered and also the type of ceiling. Costs are significantly higher for a wooden beam ceiling than for a concrete ceiling. For double concrete ceilings in a 150 m² (1,615 sq ft) house, I’d estimate about 800 euros material plus 14–16 hours of installer time.

bauenmitschaf25 Jun 2021 09:45

#17

Samantheus schrieb:

I thought you wouldn’t get comparable cooling performance with thermal activation of the concrete core?

It really depends on the design: for example, with 18°C (64°F) supply temperature, 23°C (73°F) return temperature, and 20 liters per minute (l/min) (5.3 gallons per minute) flow rate: (20*60)/1000 * 1.16 * (23-18) = 6.96 kW. However, first you need to determine the required cooling load (which is usually significantly lower than the heating load). Are there any results on this already? In my opinion, that should generally be the first step before selecting the technology.

Samantheus schrieb:

(Extra cost around 30k), flat plate collectors also have a steep surcharge (I think about 15k), and the heating contractor has never installed trench collectors. I just don’t want to be the first test customer there…

Without a trench collector, it’s absolutely not cost-effective.

Samantheus schrieb:

But for thermal activation of the concrete core, I would also need the cooling function of the air-to-water heat pump, right? Do you know approximately what costs to expect for concrete core activation and how the cooling capacity compares? I’m especially concerned about the south-facing office, which is full of heat-generating equipment, whether thermal activation of the concrete core will be sufficient in summer...

Yes, the air-to-water heat pump also requires a cooling function. Regarding cost, I would agree with Strahlemann. For the office, I would install an additional individual split air conditioning unit.

As mentioned, I would first have an energy consultant or, better yet, a mechanical and electrical (MEP) engineer determine the required cooling capacity.

One more note about the Nibe S1155-6 brine-water heat pump: It is available for a small surcharge as a PC version with passive cooling (which consumes significantly less energy), so the €3000 for the active cooling function makes little sense.

Strahleman25 Jun 2021 20:02

#18

bauenmitschaf schrieb:

One more point about the Nibe S1155-6 ground-source heat pump: It is available for a small additional cost as a PC version with passive cooling (significantly lower energy consumption), so the 3,000 EUR for the active cooling function hardly makes sense.

That is correct, I was also referring to these two versions. For us, the price difference between the S1155-6 PC and non-PC models with accessories was about 3,000 EUR.

ᐅ Cooling Concept for New Construction – Split Air Conditioning / Air-to-Water Heat Pump Cooling Function / Combination

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