ᐅ Special Case: New Construction and Heating System Upgrade

Hello everyone,

We have a special case:

We are receiving a building plot from my in-laws. An old house will be demolished, and a new solid construction will be built according to the energy-saving regulation standard (previously KfW70). Energy demand is about 7 kW (radiant floor heating).

The in-laws’ house is 20 m (65 feet) away. Their 25-year-old oil heating system is acting up, and there is a solar thermal system with 3-4 panels, about 15 years old (mostly radiators). The old oil heating has a capacity of 25 kW.

Altogether, up to 6 residential units could be created.

Now the question:
We would like to install a shared heating system since both houses remain family-owned.

What sensible modern heating technologies are possible?
Would a mini or micro combined heat and power unit (CHP) make sense?

Conditions:
- We want to move away from oil
- There is no gas connection available
- Wood is relatively easy and inexpensive to source

Thanks to the experienced heating professionals for any tips and suggestions.

Best regards,
Michael

You could calculate the performance of a wood gasification boiler combined with a properly sized layered buffer tank. This would allow you to draw water at all required temperatures and integrate solar thermal. Additionally, include a domestic hot water storage tank in the new building due to the 20 meters (65 feet) distance, as otherwise it would take too long and the circulation system would be quite long, causing significant losses. Alternatively, domestic hot water in the new building could be provided via a ventilation heat recovery system if there are only two of you. With underfloor heating, the heat loss from the pipes buried in the ground (PEX dual pipe) is around 2 to 3 W/m (0.6 to 0.9 W/ft), which is reasonable.

A combined heat and power unit without gas is hardly feasible, especially without oil.