Good day,
First, some data about the timber frame house: KfW 70 standard, heated area (including parts of the basement) about 200 m² (2,150 sq ft), underfloor heating throughout, brine heat pump, mechanical ventilation with heat recovery, consumption in 2012 around 2,500 kWh, located in a cold climate zone.
I am now considering whether a slight setback during the night might bring some energy savings, even if small. I thought of a night setback from, for example, 9:00 pm to 5:00 am by 1 degree Celsius, controlled based on the target flow temperature.
What do the experts among you think? Are such considerations worthwhile? Or does increasing/compensating the target flow temperature by one degree in the morning ultimately consume more energy? Are there any experiences, opinions, or calculation examples? Effects on the heat pump or heat source?
A significant night setback is probably less sensible.
Best regards
First, some data about the timber frame house: KfW 70 standard, heated area (including parts of the basement) about 200 m² (2,150 sq ft), underfloor heating throughout, brine heat pump, mechanical ventilation with heat recovery, consumption in 2012 around 2,500 kWh, located in a cold climate zone.
I am now considering whether a slight setback during the night might bring some energy savings, even if small. I thought of a night setback from, for example, 9:00 pm to 5:00 am by 1 degree Celsius, controlled based on the target flow temperature.
What do the experts among you think? Are such considerations worthwhile? Or does increasing/compensating the target flow temperature by one degree in the morning ultimately consume more energy? Are there any experiences, opinions, or calculation examples? Effects on the heat pump or heat source?
A significant night setback is probably less sensible.
Best regards
Your house will only have cooled down by the morning and will then need to be reheated... in the evening you will have the desired temperature again... and the cycle starts all over.
Net savings in the end: none... probably higher costs, because the system tries to heat the house up again...
Net savings in the end: none... probably higher costs, because the system tries to heat the house up again...
Mycraft schrieb:
Your house will only have cooled down by morning and will need to be reheated again... in the evening you have the desired temperature again... and the cycle repeats....
Savings in the end: none... rather higher costs, because the system tries to heat the house up again...Hello,
I don’t think the house only "cools down" by morning – the heat pump runs overnight as well, currently at -5°C (23°F) even two or three times (from 9 pm to 5 am). We are talking about only 1°C (1.8°F) lower target flow temperature here.
I thought it might be more efficient if the heat pump runs longer in the morning to compensate for the setback. I understand that a large setback doesn’t make sense here, but can we really call it reheating with just one degree difference?
Best regards
A technical book states: “The greater the heat storage capacity of a building’s internal masses and the smaller the heat losses of the building in relation, the lower the savings achievable through reduced heating operation.” In other words, a well-insulated, massive house cannot save energy through nighttime setback because the good insulation and large thermal mass delay cooling at night. On the other hand, a lightweight and poorly insulated house can indeed save energy with nighttime setback.
What is the effect with heat pumps and underfloor heating?
With heat pumps, it is generally recommended not to use setback, especially with air-source heat pumps. For underfloor heating, reheating must begin earlier due to the system’s higher thermal inertia. As a result, the savings from setback are correspondingly lower.
What is the effect with heat pumps and underfloor heating?
With heat pumps, it is generally recommended not to use setback, especially with air-source heat pumps. For underfloor heating, reheating must begin earlier due to the system’s higher thermal inertia. As a result, the savings from setback are correspondingly lower.
Hello,
thank you very much for the information.
I am exactly in between
(a very) well-insulated house, but no thermal mass except for the screed…
The issue with thermal inertia is certainly correct. I have set the start time at 7 pm and the end time at 5 am, with a reduction of 0.5 degrees Celsius (0.9°F) in the target return temperature.
Regards
thank you very much for the information.
I am exactly in between
(a very) well-insulated house, but no thermal mass except for the screed…
The issue with thermal inertia is certainly correct. I have set the start time at 7 pm and the end time at 5 am, with a reduction of 0.5 degrees Celsius (0.9°F) in the target return temperature.
Regards
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