Hello,
We are starting to get really frustrated... every builder tells us something different...
We want to build a 130sqm (1,399 sq ft) KfW 70 house with the living room facing south, and we are unsure whether to choose gas or an air source heat pump. Some providers, at almost the same price level, offer us air source heat pumps and claim that the annual costs are significantly (30%) lower compared to gas, while others doubt this.
We understand that insulation with gas/solar systems is usually better because an air source heat pump boosts efficiency more towards KfW 70 standards compared to gas/solar, which might argue in favor of gas. An air source heat pump might fail somewhat sooner, and in case of problems, you can usually get quick and competent local support with gas. With air source heat pumps, there could be more difficulties. Additionally, the noise of air source heat pumps (in our case about 3 meters (10 feet) from the neighbor) is not insignificant. Some say that sooner or later, everyone ends up having issues with neighbors for this reason.
We are interested in air source heat pumps with storage tanks from these providers: Vaillant, Mitsubishi Zubadan, and Rotex.
What we are really curious about is the annual cost for heating and hot water with both systems.
We live near Kassel.
What should we choose, and what would be cost-effective TODAY? What is your opinion on Vaillant?
Regards
Gigi
We are starting to get really frustrated... every builder tells us something different...
We want to build a 130sqm (1,399 sq ft) KfW 70 house with the living room facing south, and we are unsure whether to choose gas or an air source heat pump. Some providers, at almost the same price level, offer us air source heat pumps and claim that the annual costs are significantly (30%) lower compared to gas, while others doubt this.
We understand that insulation with gas/solar systems is usually better because an air source heat pump boosts efficiency more towards KfW 70 standards compared to gas/solar, which might argue in favor of gas. An air source heat pump might fail somewhat sooner, and in case of problems, you can usually get quick and competent local support with gas. With air source heat pumps, there could be more difficulties. Additionally, the noise of air source heat pumps (in our case about 3 meters (10 feet) from the neighbor) is not insignificant. Some say that sooner or later, everyone ends up having issues with neighbors for this reason.
We are interested in air source heat pumps with storage tanks from these providers: Vaillant, Mitsubishi Zubadan, and Rotex.
What we are really curious about is the annual cost for heating and hot water with both systems.
We live near Kassel.
What should we choose, and what would be cost-effective TODAY? What is your opinion on Vaillant?
Regards
Gigi
Is the basement insulated from the ground floor? For example, do you have an appropriate door between the ground floor and the basement?
It sounds like the basement is within the heated building envelope. In that case, it should be included in the heating load calculation, since the heated rooms contribute to heating that space. However, this is generally not advisable, because the heated rooms will need more energy to maintain the target temperature, as a lot of heat will be lost to the unheated basement — especially from the ground floor above and the two heated rooms in the basement.
In my opinion, this is not the correct approach. This could also be a reason why the person who prepared the thermal insulation verification included underfloor heating there.
You should ask about this again.
It sounds like the basement is within the heated building envelope. In that case, it should be included in the heating load calculation, since the heated rooms contribute to heating that space. However, this is generally not advisable, because the heated rooms will need more energy to maintain the target temperature, as a lot of heat will be lost to the unheated basement — especially from the ground floor above and the two heated rooms in the basement.
In my opinion, this is not the correct approach. This could also be a reason why the person who prepared the thermal insulation verification included underfloor heating there.
You should ask about this again.
R
R.Hotzenplotz7 Jan 2018 19:25No, there is no door at the basement stairs on the ground floor. And as far as I know, there are no other special measures.
How can this be fixed? I don’t need a huge heating system just to heat a guest room and a hobby room while the temperature in the other basement rooms and hallway doesn’t matter. I don’t know anyone who heats their entire basement. That’s just madness.
How can this be fixed? I don’t need a huge heating system just to heat a guest room and a hobby room while the temperature in the other basement rooms and hallway doesn’t matter. I don’t know anyone who heats their entire basement. That’s just madness.
Alex85 schrieb:
That’s actually not very wise, because in heated rooms you’ll have to use more heating to reach the target temperature, since a lot of heat is lost into the unheated basement.We’ll do it this way: door closed. Ventilation is running in the basement rooms anyway.
No one is saying that the basement rooms need to be set to 22 degrees. The heating load will not skyrocket, as your existing calculation shows.
It is just a misconception to say "I won’t install heating there," because in fact, the area will be heated anyway—just indirectly from the floor above and the adjacent heated rooms. It’s a matter of acknowledging the reality.
Basements used for storage are usually insulated against the ground floor. This means insulation is applied to the ceiling and the basement corridor is separated from the ground floor with an appropriate door. There are also floor plans where the staircase from the ground floor to the basement is open, leading into an anteroom that is insulated against the rest of the basement behind it.
It is just a misconception to say "I won’t install heating there," because in fact, the area will be heated anyway—just indirectly from the floor above and the adjacent heated rooms. It’s a matter of acknowledging the reality.
Basements used for storage are usually insulated against the ground floor. This means insulation is applied to the ceiling and the basement corridor is separated from the ground floor with an appropriate door. There are also floor plans where the staircase from the ground floor to the basement is open, leading into an anteroom that is insulated against the rest of the basement behind it.
R
R.Hotzenplotz7 Jan 2018 20:04So basically, I can probably skip the effort of checking whether the 7.58 W heating load for the 304 m² (3,270 sq ft) house, or 234 m² (2,520 sq ft) ground and upper floors, is accurate or not, right? The value seems reasonable for this size. And it’s just an Energy Saving Ordinance 2016 house, nothing more. Although the ceiling heights had to be reduced by a total of 20 cm (8 inches) after the calculation was done (thanks to the building authority), this probably won’t lead to a reassessment of the relevant heating systems.
As mentioned, an energy consultant will be hired tomorrow to run the calculations.
As mentioned, an energy consultant will be hired tomorrow to run the calculations.
As for the area, I think it feels completely fine.
You’ve already paid someone to run the calculations; otherwise, you wouldn’t have the document in your hands. If you have any questions, direct them to that person. However, I recommend consulting an energy consultant—someone who specializes in this full-time (not a structural engineer or similar who also does thermal insulation calculations)—especially for choosing your heating system. In particular, whether you can manage with gas plus controlled ventilation, or if you need solar thermal with gas (general contractors usually just say “yes, you need it”). If you are already leaning towards an air-to-water heat pump, you can probably skip this.
You’ve already paid someone to run the calculations; otherwise, you wouldn’t have the document in your hands. If you have any questions, direct them to that person. However, I recommend consulting an energy consultant—someone who specializes in this full-time (not a structural engineer or similar who also does thermal insulation calculations)—especially for choosing your heating system. In particular, whether you can manage with gas plus controlled ventilation, or if you need solar thermal with gas (general contractors usually just say “yes, you need it”). If you are already leaning towards an air-to-water heat pump, you can probably skip this.
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