One degree less
Every degree less in room temperature saves around 6 per cent of heating energy. You often hardly notice the difference between 21 and 20 °C.
Service
Saving energy: in everyday life and in the building
Because heating and hot water costs are billed according to consumption, every kilowatt hour saved pays off directly in your own statement. Here you will find everyday tips without any loss of comfort — and, for owners, the measures that bring the most in the long term: from optimising the system to renovation.
− 1 °Caround 6 % less heating energy
5–10 minopen windows wide instead of tilting them permanently
16 °Clower limit so that nothing cools down
1. Envelopethen heating — the right order of renovation
Heating correctly
The biggest lever: space heating accounts for the lion’s share of energy used in a household.
20 °CLiving room
22 °CBathroom
18 °CKitchen
17 °CBedroom
Heat rooms to different temperatures
Not every room needs the same warmth: living room around 20 °C, kitchen around 18 °C, bedroom around 17 °C. Keep doors to cooler rooms closed.
Set the thermostat correctly
On most thermostatic valves, setting 3 corresponds to about 20 °C. Turning it all the way up does not heat faster, only for longer — the room overheats.
Do not let rooms cool down
Even when you are away, rooms should not drop below about 16 °C. Reheating cold walls costs energy and encourages mould.
Keep radiators clear
Furniture, long curtains or covers in front of the radiator trap the heat. Laundry does not belong on the radiator — it covers it and brings moisture into the room.
Bleed radiators
If the radiator gurgles or does not get warm at the top, there is air in the system. Bleeding it improves heat output. If in doubt, ask the property management.
Close shutters at night
Closed roller shutters and curtains noticeably reduce heat loss through the windows — but they must not cover the radiators.
Programmable thermostats
Electronic thermostats automatically lower the temperature at night or during working hours and heat up again in good time.
Ventilating correctly
Fresh air is important — what matters is how you ventilate.
RecommendedOpening wide briefly
- ✓ Open windows wide, 5–10 minutes
- ✓ 3 to 4 times a day
- ✓ Air is exchanged, walls stay warm
- ✓ Turn the heating off meanwhile
AvoidPermanently tilted
- ✕ little air exchange
- ✕ window reveal and wall cool down
- ✕ heating works against the open window
- ✕ increased risk of mould
Open wide instead of tilting
Open the windows wide three to four times a day for five to ten minutes, rather shorter in winter. This exchanges the air without the walls cooling down.
No permanently tilted windows
A permanently tilted window exchanges little air but cools the window reveal and wall. This costs a lot of energy and encourages mould.
Turn the heating down while ventilating
Turn the thermostat off while the window is open. Otherwise the valve opens and heats straight to the outside.
Air out moisture straight away
Ventilate briefly straight after showering, cooking or drying laundry. Dry air can be warmed faster than humid air.
Hot water and water
Hot water accounts for a considerable part of energy costs — and is billed according to consumption.
Shower instead of bathing
A full bath needs many times the water of a short shower. Showering for less time saves even more.
Water-saving shower head and aerators
Water-saving shower heads and flow regulators on the taps significantly reduce the flow without any loss of comfort.
Repair dripping taps
A dripping tap or a running cistern loses several thousand litres over the year. A look at the water meter with all taps closed shows whether anything is running.
Do not set hot water too cold
For hygiene reasons, central hot water tanks must be operated at a sufficiently high temperature to prevent legionella. So save on the quantity, not on the tank temperature.
Electricity in the household
Electricity can also be saved with little effort.
LED instead of incandescent bulbs
LED lamps need only a fraction of the electricity of conventional incandescent bulbs and last much longer.
Fully load appliances
Only run the dishwasher and washing machine when fully loaded and use eco programmes — they take longer but use less energy.
Air-dry laundry
A tumble dryer uses considerably more electricity than the washing machine. If you use one, clean the lint filter regularly.
Avoid standby
Switchable power strips completely disconnect televisions, router peripherals and chargers from the mains.
Optimising the system: for owners and property managers
Low-investment measures on the heating system benefit all residents at once and usually pay for themselves quickly.
Hydraulic balancing
Hydraulic balancing ensures that each radiator receives exactly the amount of water it needs. The system works more efficiently and radiators heat up evenly.
Insulate pipes
Previously uninsulated, accessible heating and hot water pipes in unheated rooms must be insulated under § 71 of the Buildings Energy Act (Gebäudeenergiegesetz, GEG). Insulated pipes also reduce the problem of unmetered pipe heat.
Check the heating curve and setback
A heating curve set too steeply wastes energy. Night-time and weekend setback should match actual usage patterns.
Efficient circulation pump
Old, unregulated heating pumps often run around the clock at full power. High-efficiency pumps need only a fraction of the electricity.
Make consumption visible
Remotely readable devices and the monthly consumption information show residents early on how their consumption is developing — an effective incentive to save.
Reduce communal electricity
LED lighting with motion detectors in the stairwell, basement and underground car park, as well as coordinated running times for ventilation systems, reduce the community’s electricity costs.
You can read more about how uninsulated pipes distort the billing in the article Pipe heat according to VDI 2077.
Renovating: larger measures on the building
The greatest savings lie in the building envelope and the heating technology. Such measures are expensive, but they are subsidised and increase the value of the property.
- External walls20–30 %
- Windows15–25 %
- Roof / top ceiling15–20 %
- Ventilation10–20 %
- Basement / floor5–10 %
Plan first: renovation roadmap
An individual renovation roadmap (individueller Sanierungsfahrplan, iSFP) drawn up by an energy efficiency expert shows which measures make sense and in which order. The energy consultation is subsidised, and the roadmap increases the funding for later individual measures.
Insulate the roof and top floor ceiling
Warm air rises — an uninsulated roof loses a lot of heat. Insulating the top floor ceiling below an unheated loft is often inexpensive and in many cases even mandatory under § 47 GEG.
Insulate the façade
In unrenovated buildings, most of the heat is usually lost through the external walls. Insulation is most economical when scaffolding and plastering work are due anyway.
Insulate the basement ceiling
Insulation boards on the underside of the basement ceiling are a comparatively simple measure that noticeably improves cold floors on the ground floor.
Replace windows
Modern windows with triple glazing and tight frames lose many times less heat than old single glazing or early insulating glazing. Important: after replacement, ventilate differently, because air no longer leaks through the joints.
Renew the heating
Replace old oil and gas boilers with an efficient system — such as a heat pump, a district heating connection or a hybrid solution. A heat pump works more efficiently the lower the required flow temperature is, i.e. the better the building is insulated.
Ventilation with heat recovery
After a comprehensive renovation, the building is very airtight. A ventilation system with heat recovery provides fresh air, prevents mould and recovers a large part of the heat from the exhaust air.
Use solar energy
Photovoltaics on the roof reduce communal electricity or can supply residents via a tenant electricity scheme (Mieterstrom). Solar thermal systems support hot water heating and space heating.
- Get adviceEnergy consultation and renovation roadmap (iSFP)
- Secure fundingSubmit applications before the measure begins
- Improve the envelopeRoof, façade, windows, basement ceiling
- Renew the heatingsmaller design, low flow temperature
- Fine-tunehydraulic balancing, heating curve, check consumption
Funding
- BAFA (Federal Office for Economic Affairs and Export Control): grants for individual measures on the envelope and system technology, increased with a renovation roadmap
- KfW (the German state development bank): grant for replacing the heating, tiered into basic and bonus funding
- KfW: subsidised loans for renovation to an efficiency house (Effizienzhaus) standard
- Energy consultation and renovation roadmap are subsidised
- Owner-occupiers alternatively: tax reduction under § 35c of the Income Tax Act (Einkommensteuergesetz, EStG)
WEG
- In a WEG (Wohnungseigentümergemeinschaft, the community of flat owners), energy-efficiency measures are structural alterations (§ 20 WEG)
- Resolution by simple majority at the owners’ meeting
- All owners bear the costs in the case of a qualified majority or payback (§ 21 WEG)
- Financing from the maintenance reserve, a special levy or a WEG loan
Letting
- Announcement at least three months in advance (§ 555c of the German Civil Code, Bürgerliches Gesetzbuch, BGB)
- Rent increase of 8 % of the costs per year, with a cap (§ 559 BGB)
- Special rule for subsidised heating replacement (§ 559e BGB)
- A better energy balance reduces the landlord’s share of the CO₂ costs
Funding programmes and funding rates change frequently. The current guidelines of BAFA and KfW are authoritative; applications must generally be submitted before the measure begins.
How the energy balance affects the split of CO₂ costs between landlord and tenant is explained in the article CO₂ cost allocation.
Frequently asked questions about renovation and funding
Which renovation measure saves the most energy?
That depends on the building. In unrenovated houses, the greatest amounts of heat are usually lost through the external walls, windows and roof. An individual renovation roadmap from an energy consultant shows which measure is most worthwhile.
In which order should you renovate?
As a rule, first the building envelope, then the heating. Once the building is insulated, the heat demand falls and the new heating can be designed smaller. A heat pump also works more efficiently if low flow temperatures are sufficient thanks to good insulation.
Are there renovation obligations under the Buildings Energy Act?
Yes, some retrofitting obligations: the top floor ceiling must be insulated if it does not meet the minimum thermal insulation (§ 47 GEG), uninsulated accessible heating and hot water pipes in unheated rooms must be insulated (§ 71 GEG), and many oil and gas constant-temperature boilers may no longer be operated after 30 years (§ 72 GEG). Anyone renewing external building components must comply with the minimum values under § 48 GEG.
What funding is available for renovations?
For individual measures on the building envelope and system technology, grants are available from the BAFA, for replacing the heating grants are available from the KfW, plus subsidised loans for comprehensive renovations. Energy consultation is also subsidised. Applications must generally be submitted before the measure begins; the conditions change quite often.
How does a WEG decide on an energy-efficient renovation?
Energy-efficiency measures on the common property are structural alterations that the owners’ meeting can approve by simple majority (§ 20 (1) WEG). Who bears the costs is governed by § 21 WEG: all owners pay if the resolution was passed with more than two thirds of the votes cast and half of the co-ownership shares, or if the costs pay for themselves within a reasonable period.
May landlords pass the costs of a renovation on to the rent?
Energy-efficiency modernisations entitle landlords to a rent increase of 8 per cent of the costs per year, capped at 3 euros per square metre within six years, or 2 euros for rents below 7 euros per square metre (§ 559 BGB). For a subsidised heating replacement, § 559e BGB applies as an alternative. The modernisation must be announced at least three months in advance (§ 555c BGB).
These notes are for general guidance only and replace neither an energy consultation nor legal advice in an individual case. As of: September 2026.
Keep an eye on your own consumption
With the monthly consumption information, you can see how your heating and hot water consumption is developing — compared with the previous month, the previous year and an average household. This way you notice immediately whether your saving measures are paying off — even after a renovation.