Indoor temperature — reference values and owner duties

The reference values for indoor temperature sit in the Swedish Public Health Agency's general recommendations HSLF-FS 2024:10, in force since 15 May 2024, which replaced the earlier recommendations FoHMFS 2014:17. They support municipal environmental committees in supervising dwellings and premises for public purposes, and they support you as property owner — referred to in the recommendations as the operator (verksamhetsutövare) — in ensuring the operation is run in accordance with the Environmental Code.

If the temperature is not kept within the reference values it may constitute a detriment to human health. Not automatically, but that is the starting point for the committee's assessment.

The reference values

Lowest indoor temperature

Parameter	Reference value
Lowest operative temperature	18 °C
Lowest operative temperature, sensitive group	20 °C
Lowest floor surface temperature	16 °C
Lowest floor surface temperature, sensitive group	18 °C
Highest mean air velocity at indoor temperatures up to 24 °C	0.15 m/s

Highest indoor temperature

Period	Parameter	Reference value
Autumn, winter, spring	Highest operative temperature	24 °C
Summer	Highest air temperature	26 °C

For sensitive groups the summer value applies around the clock. For others a somewhat higher temperature may be acceptable during the day, but it should not exceed 26 °C at night.

Do we have to keep 20 degrees?

That is the most common misconception, and it comes from the old recommendations. The general reference value for the lowest operative temperature is 18 °C. 20 °C is the value for a sensitive group — people sensitive to cold or heat, for example those with chronic illness or disability, as well as the elderly and small children.

The earlier recommendations also gave a recommended range of 20–23 °C that was frequently quoted as a requirement. That range is not in HSLF-FS 2024:10. Many pages online still reproduce the old figures — go to the regulation itself when the question turns sharp.

Three terms that decide how measurement is done

• Operative temperature is the mean of the air temperature and the mean radiant temperature from surrounding surfaces. That is why a flat with cold external walls can be at 21 °C in the air and still below the reference value.
• The occupied zone (vistelsezonen) is the area bounded by two horizontal planes, 0.1 metres and 2.0 metres above the floor, and vertically 0.6 metres from an external wall — but 1.0 metre in front of a window or external door. Temperature and mean air velocity are to be measured there, not in the middle of the room at ceiling height.
• Floor temperature is measured directly on the floor.

For summer it is usually sufficient to measure air temperature, which is why the value for that period is stated as air temperature rather than operative temperature.

What is new in the 2024 recommendations: heat

The major change from the old recommendations is the focus on high temperatures. The recommendations state that you should plan and adapt the operation in the knowledge that the climate is warming, and carry out measures that prevent high indoor temperatures in both the short and the long term. The measures named are

• solar shading at windows with direct solar gain,
• preserving and planning for shade trees,
• ensuring windows can be opened for ventilation safely,
• remedying deficient insulation,
• work on the ventilation, and
• investigating the need for and feasibility of comfort cooling.

The recommendations also say that measures requiring less energy should be preferred where they suffice, and that regard should be had to outlook, daylight and noise in the choice — a window film that darkens the room solves one problem and creates another.

On an SMHI warning or notice of high temperatures you should be especially attentive: inform residents about ventilating when it is cooler outside, inform them how to use solar shading, prioritise complaints relating to heat, and ensure sensitive individuals have access to cool spaces. This applies particularly in residential care homes, short-term care, supported housing and preschools.

What the recommendations require of self-monitoring

HSLF-FS 2024:10 points directly at Environmental Code Ch. 26 s. 19 and lists what the routines may cover:

• maintenance and servicing of heating systems, any cooling systems and other installations affecting the thermal indoor climate,
• the need for insulation measures,
• monitoring of indoor temperature, and
• handling of complaints and fault reports.

The last point is where supervision catches people out. A complaint about a cold flat that was not registered, investigated and closed is hard to account for after the fact. See self-monitoring under the Environmental Code.

The recommendations also invoke the knowledge requirement in Environmental Code Ch. 2 s. 2: you should be able to judge what measures are needed, which among other things presupposes good knowledge of the building's heating system.

The link to ventilation

Draught is part of the same assessment — the highest mean air velocity of 0.15 m/s sits in the same table as the temperature. Badly balanced ventilation produces both draught and uneven temperature, and a complaint about cold in a flat is as often a ventilation problem as a heating problem.

That means a temperature case at the environmental committee and a ventilation remark at the building committee can concern exactly the same installation, seen by two authorities from two directions. See ventilation remarks and the annual calendar.

Emphyx does not measure temperature and does not receive sensor data. What can be handled in the inspection round checklists is the manual check — measurement on complaint, recorded per building and flat with a date, so a case can be followed from report to closure.