Is it practical to heat a single-family house (approx. 140 m² (1,500 sq ft)) with KfW55 insulation standard and triple glazing solely using a ventilation heating system? What are the differences between the prefab house manufacturers Weberhaus (Proxon), Proxon sales (Zimmermann ventilation), and Schwörerhaus (heat recovery 134 BPHK)? Which system is better, and why?
Would a geothermal heat exchanger be useful for both systems?
Do both systems require an additional heat pump for domestic hot water?
In which rooms would additional electric heaters be necessary?
Would a geothermal heat exchanger be useful for both systems?
Do both systems require an additional heat pump for domestic hot water?
In which rooms would additional electric heaters be necessary?
Almost two years ago, we built a house (Bien-Zenker) with the Proxon ventilation heating system, an energy-efficient house rated at 55, including a fireplace and a ground-source heat exchanger (the latter was installed by ourselves). I would definitely do it again. A domestic hot water heat pump is, of course, necessary and is included in the package. It is very efficient in summer but somewhat less so in winter, as it uses the exhaust air from the Proxon heating system (in summer: heating off, exhaust air > 20°C (68°F); in winter: heating on, exhaust air minus 8°C (17.6°F)). For a household of four, we need about 900 kWh of electricity per year for water heating.
I would always recommend including the ground heat exchanger, as it was able to warm the supply air to plus 2°C (35.6°F) even at ambient temperatures of minus 15°C (5°F), and cool it from 30°C (86°F) to 18°C (64.4°F) in summer. This allows the Proxon system to operate efficiently even in the coldest winter months. In both winters, the PTC electric heaters were not needed; instead, the soapstone fireplace was occasionally used during winter.
Auxiliary heating is required for comfort, especially in bathrooms. We installed infrared panels instead of the offered convection fan heaters. This was not necessarily worthwhile, as IR heaters are somewhat slower to respond; we only use them when the children are taking baths.
Regarding comfort: radiant heat is missing. Anyone who wants to sleep at 23/24°C (73/75°F) in winter and sit in front of the TV wearing only a T-shirt will not be happy. The heating system provides around 21°C (70°F), which is the limit with 42°C (108°F) supply air temperature from the heat pump; higher temperatures are possible, of course, with PTC electric heating. But with the fireplace, it’s enjoyable.
What’s great is the always fresh air, absolutely no drafts, no noise, and the heating system responds quickly: when the sun shines through the south-facing windows in winter, the system immediately switches off, as it does during fireplace operation as well.
I would always recommend including the ground heat exchanger, as it was able to warm the supply air to plus 2°C (35.6°F) even at ambient temperatures of minus 15°C (5°F), and cool it from 30°C (86°F) to 18°C (64.4°F) in summer. This allows the Proxon system to operate efficiently even in the coldest winter months. In both winters, the PTC electric heaters were not needed; instead, the soapstone fireplace was occasionally used during winter.
Auxiliary heating is required for comfort, especially in bathrooms. We installed infrared panels instead of the offered convection fan heaters. This was not necessarily worthwhile, as IR heaters are somewhat slower to respond; we only use them when the children are taking baths.
Regarding comfort: radiant heat is missing. Anyone who wants to sleep at 23/24°C (73/75°F) in winter and sit in front of the TV wearing only a T-shirt will not be happy. The heating system provides around 21°C (70°F), which is the limit with 42°C (108°F) supply air temperature from the heat pump; higher temperatures are possible, of course, with PTC electric heating. But with the fireplace, it’s enjoyable.
What’s great is the always fresh air, absolutely no drafts, no noise, and the heating system responds quickly: when the sun shines through the south-facing windows in winter, the system immediately switches off, as it does during fireplace operation as well.
...and regarding electricity consumption, 170 m² (1830 sq ft), 4 people: about 900 kWh for hot water (I have a meter for that) and an estimated 2000 kWh for heating. We run everything in the house through one meter, including household electricity (estimated just under 3500 kWh), totaling 6000–6500 kWh, of which the photovoltaic system (7.2 kWp) contributes 2000–2500 kWh for self-consumption, so including household electricity we consume about 4000 kWh of electricity per year (and sell 5500–6000 kWh of photovoltaic power).
Additionally, 1–2 cords of firewood...
The approximately 3000 kWh for heating and hot water are certainly the lower limit for a 170 m² (1830 sq ft) Energy Efficiency House 55, as this is without any electrical supplementary heating, which we do not use.
The Proxon system is suitable for me if:
- Energy Efficiency House 55 or better, airtight!
- occupants less sensitive to cold (due to lack of radiant heat)
- south-facing house with many windows
- photovoltaic system and fireplace planned anyway
Additionally, 1–2 cords of firewood...
The approximately 3000 kWh for heating and hot water are certainly the lower limit for a 170 m² (1830 sq ft) Energy Efficiency House 55, as this is without any electrical supplementary heating, which we do not use.
The Proxon system is suitable for me if:
- Energy Efficiency House 55 or better, airtight!
- occupants less sensitive to cold (due to lack of radiant heat)
- south-facing house with many windows
- photovoltaic system and fireplace planned anyway
H
Hausqualle22 Jul 2015 20:25Fiorino schrieb:
Oh yes, I forgot to mention earlier.... ... in the USA, residential houses usually have a single heating and cooling system ... when it’s too hot outside, it switches to cooling mode and the house stays comfortably cool ..Yeah, and the humidity in winter is 0%... at least in the USA – but houses there tend to have drafts.
Also, underfloor heating doesn’t work on the principle of “heater on, room warm” (just as a side note) – the usual advice is actually not to let the house cool down at all, or so I’ve heard.
5500 kWh of pure electricity?! That’s $120 / month – for a new build with the described limitations, that doesn’t sound very appealing. However, in Melvilli’s second post, the consumption figures look more favorable.
I would have thought this system is only suitable for passive houses – for anything else, rather suboptimal.
Definitely very interesting reports – thanks for sharing.
Also, underfloor heating doesn’t work on the principle of “heater on, room warm” (just as a side note) – the usual advice is actually not to let the house cool down at all, or so I’ve heard.
5500 kWh of pure electricity?! That’s $120 / month – for a new build with the described limitations, that doesn’t sound very appealing. However, in Melvilli’s second post, the consumption figures look more favorable.
I would have thought this system is only suitable for passive houses – for anything else, rather suboptimal.
Definitely very interesting reports – thanks for sharing.
Just throwing all the numbers around doesn’t provide much clarity. In addition to factors like the number of occupants and the heating load, the climate zone is also very important. In the Rhine Valley, an air-to-air heat pump can work very well in a KFW55 house, and it can also work in Upper Franconia in the same type of house—however, with significantly higher electricity costs and possibly only about 19°C (66°F) in the living room.
A quick search reveals many homeowners dissatisfied with air-to-air heat pumps—and the general consensus is that an air-to-air heat pump is only suitable for KFW55 houses (depending on the climate region) or better.
For example, Fiorino on page 1: a KFW70 house with an electricity consumption of 5500 kWh plus wood for the fireplace used for heating, ventilation, and hot water. The consumption is enormous—unless the house is around 350 m² (3800 ft²) and occupied by 8 people, or located at the Zugspitze summit. But Fiorino is satisfied...
In comparison, we only use a ground-source heat pump without a fireplace in a 200 m² (2150 ft²) house (including a partially heated basement) with 4 people including hot water, in the coldest climate zone in a KFW70 house, and last year we consumed less than one third of that amount.
A quick search reveals many homeowners dissatisfied with air-to-air heat pumps—and the general consensus is that an air-to-air heat pump is only suitable for KFW55 houses (depending on the climate region) or better.
For example, Fiorino on page 1: a KFW70 house with an electricity consumption of 5500 kWh plus wood for the fireplace used for heating, ventilation, and hot water. The consumption is enormous—unless the house is around 350 m² (3800 ft²) and occupied by 8 people, or located at the Zugspitze summit. But Fiorino is satisfied...
In comparison, we only use a ground-source heat pump without a fireplace in a 200 m² (2150 ft²) house (including a partially heated basement) with 4 people including hot water, in the coldest climate zone in a KFW70 house, and last year we consumed less than one third of that amount.
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