The heating is on, the living room gets warm — and yet there is a draft at the window. At the same time a room remains surprisingly cool, even though the thermostat is set high. With the next bill in mind, people look for quick fixes. This is precisely where Saving energy in rental apartments takes a pragmatic approach: measures that work without renovation, can be checked immediately and, if necessary, can be reverted without leaving traces.
This practical guide deliberately focuses on the levers tenants actually control: heating, ventilation, domestic hot water and electricity. You get a sequence, short everyday tests, typical fault patterns — and clear stop-or-escalation points if the real problem is not behavior but the building or building services.
Starting question: How can you tell that energy is currently being lost „in the wrong place“?
Before you buy anything or change routines, a quick reality check helps. In rental apartments three consumption blocks typically dominate: room heating, hot water and household electricity. Which block is currently „running away“ in your case is often visible from simple observations:
- Heating: You turn the dial up frequently, rooms heat unevenly, it feels drafty, or windows show heavy condensation.
- Hot water: Shower times are long, bathing is routine, or hot water is generated electrically (instantaneous water heater/boiler).
- Electricity: Many devices run in the background (standby), or there are genuine continuous consumers such as refrigerators/freezers.
Short log worth keeping: Over 5 to 7 days note (1) approximate room temperatures and (2) typical humidity peaks (showering, cooking, sleeping). A simple thermometer/hygrometer is sufficient. This lets you see more quickly whether you should mainly address heat losses, incorrect ventilation, or hot-water/electricity habits.
Saving energy in rental apartments: heating without renovation — what has immediate effect
1) Lower room temperature in small steps and keep it stable
If you want to test only one measure: lower the room temperature by a small step and then keep it stable. The Umweltbundesamt cites „lowering room temperature“ as an effective short-term action.[Source] A UBA report also gives a rule of thumb: 1 °C less room temperature can save about 6 % energy.[Source] The figure is not a firm guarantee — building, weather and behavior change the result — but it indicates the direction: small corrections have an effect on every heating day.
What matters is the limit. If you reduce too far, surfaces can cool; moisture then condenses more easily. In addition there are health-related frameworks: the WHO cites 18 °C as a reference value and stresses that for certain population groups and circumstances higher minimum temperatures may be sensible or necessary.[Source] Practical implication: lower stepwise, monitor comfort and humidity, and avoid “everything at once”.
2) Set thermostats correctly: room-by-room instead of „one number for everything“
Many apartments are heated inefficiently because the same thermostat setting applies everywhere. A room-by-room logic is more sensible: warmer where you spend more time; cooler where you sleep or rarely go. The UBA recommends room-by-room temperature settings and points out that more precisely regulating thermostatic valves can reduce energy consumption.[Source]
A common misunderstanding: the thermostat is not an accelerator pedal. Turning it up very high does not make a room „heat faster“; it raises the target temperature until the control closes again. For everyday operation a clear set of modes works well: Normal (when you are present), Away (during the day) and Night. Few, repeatable settings are more stable than constant readjustment.
3) Door management: keep heat where you need it
Open doors feel generous but are often an energy leak: warm air moves into cooler zones, which you then unintentionally heat. The UBA names keeping doors of heated rooms closed — including towards less-heated rooms — as a concrete measure.[Source]
The consequence is simple: if you want zones with different temperatures, you need boundaries. In rental apartments the door is often the most important „control“ available without structural changes.
4) Keep radiators clear and, if responsible, bleed them
Radiators work more efficiently when they can emit heat unobstructed. Furniture directly in front, curtains over them or laundry on the radiator impede air circulation and make thermostatic control imprecise. The UBA recommends as an immediately actionable measure not to cover radiators and to bleed them regularly.[Source]
Context for rental apartments: depending on house rules, bleeding may be the responsibility of the property management or part of the tenant’s duties. If you are permitted to bleed radiators yourself, take care: hot water may be released. If there is constantly air in the system or radiators repeatedly remain cold, this is not a „bleed more often“ issue but an escalation point for the property management.
Proper heating and ventilation: save energy without provoking humidity problems
Shock and cross-ventilation instead of tilt ventilation
Tilting windows may seem harmless, but during the heating season it is often an expensive continuous loss: building components cool down, and the heating system works against a permanent leak. The Verbraucherzentrale recommends short, full-window ventilation several times daily during the heating season and warns against keeping windows tilted open permanently, because this causes energy losses and can cool down building components.[Source]
Everyday translation: Open windows fully for short, clear intervals. Cross-ventilation (opposite windows opened simultaneously) speeds up air exchange. Then close them again consistently.
Event-based ventilation: actively remove moisture peaks
Humidity is the factor that can quickly turn energy saving into a risk. When you lower the temperature, surfaces are more likely to become cold — and moist air then condenses more easily. That is why an event-based control works better than fixed times: ventilate promptly after showering, cooking and sleeping. The Verbraucherzentrale emphasizes that moist air after such situations should be exchanged quickly; regular short or cross-ventilation helps with air exchange and can prevent mold.[Source]
A small hygrometer is more than a „gadget“ here: it makes visible whether a temperature setback and your ventilation intervals match. People who act only by feel often overheat out of concern or ventilate for too long out of habit.
Hot water savings: reversible, but with priorities
Domestic hot water is often underestimated in everyday life — especially when it is produced electrically. The UBA lists effective measures among others: low-flow showerhead, showering instead of bathing, turning off the water while soaping, and repairing dripping taps.[Source] The advantage in rented apartments: many measures are possible without intervention in the building fabric.
Showering instead of bathing: the biggest lever when bathing is routine
If bathing is a regular occurrence for you, it is usually the single largest hot-water lever. The UBA gives as a rule of thumb: one bath corresponds approximately to three showers (at about 6 minutes).[Source] As a decision aid this is valuable, even though your individual consumption may vary depending on the fitting and habits.
Low-flow showerhead: test first, then keep
A low-flow showerhead reduces flow and can therefore reduce hot-water and energy consumption. The limit is technical: some instantaneous water heaters require a minimum flow, otherwise the temperature fluctuates or control becomes unstable. The rental-apartment-compatible approach is therefore a test: install, observe two to three uses, then decide. Abort criterion: noticeably fluctuating temperature or reduced user comfort – then revert or choose a different model.
Leaking fittings: report instead of „DIY repairs“
A dripping tap is maintenance. Depending on the system, not only water but also energy for heating it is lost. In rental apartments „repairing it yourself“ is often problematic (liability, consequential damage). Practical approach: briefly document (photo/video), report in writing, arrange an appointment.
Saving electricity in the rental apartment: less continuous operation instead of abstention
For electricity it is rarely single „savings actions“ that decide, but continuous loads. You do not have to live ascetically, but you should determine what really needs to run permanently.
Reduce standby consumption: think in device groups
Consumer electronics, monitors, peripherals, printers: many devices continue to draw power in standby. A switchable power strip makes sense when you can separate whole device groups cleanly. The important step is organizational: what must run 24/7 (e.g. router if telephony depends on it)? What can be turned off at night or during absence? Once this decision is made, the measure becomes permanent – not a daily discussion.
Lighting: LEDs as a straightforward measure
If halogen or very old lamps are still in use, switching to LEDs is one of the simplest electricity measures without remodeling. In everyday life the point is less „as bright as possible“ than appropriate light points: illuminate work surfaces specifically, instead of permanently lighting the whole room at maximum.
Cooling and freezing: first check operation, then consider replacement
Refrigeration appliances are continuous runners. Without remodeling you can often improve them: Can the unit dissipate heat at the back (clearance to the wall)? Do the seals close properly (paper-strip test: a trapped strip of paper that can be pulled out very easily = seal likely weak)? Is the temperature unnecessarily low? Is the unit heavily iced? Icing often costs efficiency and space. These checks cost little to nothing and are particularly appreciated in rental apartments.
Decision aid: Which measure fits which symptom?
| Observation | Likely cause | Immediate measure without retrofit | Abort/escalation point |
|---|---|---|---|
| It feels drafty even though the heating is set high | Drafts, incorrect ventilation, radiator obstructed | Draft check at windows/doors, brief intensive ventilation instead of tilting, keep radiators clear | If the draft clearly comes from defective seals/windows: document and inform the landlord/property manager |
| High heating costs, but only a few rooms are used | No zoning, doors open, same thermostat setting everywhere | Room-specific temperature strategy, door management, define away state | If individual rooms do not warm up despite normal settings: have radiator/system checked |
| Windows fogged, corners smell musty | Humidity spikes, incorrect ventilation habits, cold surfaces | Event-driven short intensive airing, ventilate bathroom/kitchen promptly, avoid excessive temperature setpoints | If visible mold or recurring stains: determine cause and file a formal report |
| Electricity bill comes as a surprise, although devices are not new | Standby power, always-on devices, inefficient lighting | Switchable power strips for device clusters, LED lighting, check refrigeration operation | If unclear: systematically record meter readings or use a measurement device |
| Hot water acts as a cost driver | Long shower times, high flow rate, dripping faucet | Trial a low-flow showerhead, turn off water while soaping, report drips | If temperature fluctuations occur on the tankless water heater: revert the measure and have the system inspected |
Constructed everyday scenario: The 30-minute check before you spend money
Implementation as a plan: 7 steps to maintain in daily routine
- Define baseline: Set a target temperature for each room. Keep initial changes small.
- Replace ventilation habit: Replace tilted-window airing with short intensive or cross-ventilation, especially after showering, cooking and sleeping.
- Check radiators: Remove curtains, furniture, laundry that block heat emission. Clarify responsibility for bleeding (venting) radiators.
- Create zones: Use doors between warm and cooler areas intentionally instead of leaving everything open as the default.
- Prioritize hot water: Reduce baths (if relevant), adjust shower routine, retain a low-flow showerhead only after a compatibility test.
- Set up standby zones: Group device clusters (media, workspace) on switchable power strips; continuous operation only where necessary.
- Check after 14 days: Monitor comfort, condensation and humidity. If humidity rises or rooms become uncomfortably cold: adjust cautiously, rather than lowering further.
Typical fault patterns — and how to recognize them early
Fault 1: Letting rooms cool down excessively and later „force-heating“ them
Very cold rooms can promote moisture problems and later require high reheating energy. In practice, a moderate setback is usually the more stable strategy: you save energy without letting surfaces cool down excessively. If rooms feel uncomfortable despite an „apparently warm“ air temperature, first check for drafts and the radiator environment before turning the thermostats up further.
Error 2: Continuous tilt ventilation as presumed mold prevention
Windows left tilted open permanently are not automatically safer, but are often more expensive. Short, cross-ventilation typically removes moisture faster without cooling building components for a long time. If condensate occurs regularly, that is a signal about timing and temperature balance — not an argument for keeping the window open permanently.
Error 3: Buying before the bottleneck is clear
A new shower head helps little if the tap leaks or the instantaneous water heater oscillates strongly at low flow. A power strip saves little if the main consumption is a frozen refrigeration unit. Sequence remains the most reliable saving strategy: observe, test small, then decide.
Safe stop and escalation points: When to stop and clarify responsibilities
Some causes cannot be „optimized away.“ In rental apartments it makes sense to recognize early when the issue is one of maintenance or safety.
- Windows/doors close poorly: If drafts clearly originate from the building element, document and report them instead of concealing them.
- Radiators stay cold or gurgle persistently: A one-time bleeding may help; recurring problems belong to the property management.
- Visible mold or recurring damp stains: Do not „regulate it away.“ Clarify the cause, report correctly, and if necessary keep a ventilation/heating log. For health complaints, qualified medical advice is the appropriate course.
- Electrical anomalies: Warm sockets, a smell of burning, or flickering power strips are not energy-saving issues: stop immediately and call in professional help.
Final thought: Savings arise from stable operation
Lower consumption in rental apartments rarely comes from a trick, but from a system that fits together: moderate, room-by-room temperatures; short, effective ventilation; unobstructed radiators; doors used for zone control; a hot-water routine with realistic tests; and a clear view of continuous power consumers. If comfort or moisture balance deteriorates after two weeks, that is not a sign that saving energy „doesn’t work,“ but an indication that you should readjust — before a saving turns into a consequential cost problem.
Sources and further information
The key technical statements were editorially contextualized based on the following external sources.
- Understandable monthly heating information as the key to reducing consumption (www.umweltbundesamt.de)
Rule of thumb: 1 °C lower room temperature can save about 6 % of heating energy; additionally recommendations on room-by-room temperature settings, keeping doors closed, keeping radiators unobstructed and bleeding them, as well as hot-water measures such as a water-saving shower head and showering instead of bathing. - Heating: 10 simple tips to save on heating costs | Verbraucherzentrale.de (www.verbraucherzentrale.de)
Short, intensive ventilation (opening windows briefly) instead of continuous tilt ventilation is recommended to avoid energy loss. - Heating and ventilating: How to do it correctly | Verbraucherzentrale.de (www.verbraucherzentrale.de)
Targeted ventilation after moisture peaks (showering, cooking, sleeping) helps with air exchange and prevents mold. - WHO HOUSING AND HEALTH GUIDELINES (iris.who.int)
The WHO cites 18 °C as a reference for minimum indoor temperatures and notes that higher temperatures may be required for certain groups. - Policy recommendations for energy saving | Umweltbundesamt (www.umweltbundesamt.de)
Lowering room temperature and adjusting the heating are cited as short-term effective measures.
For this topic, Reducing heating costs without renovation and Hot water savings — shower are also important. The article classifies these aspects clearly and explains what matters in everyday practice.