German law gives you no general right to „Hitzefrei” — a free afternoon when the office overheats. But it does impose a graded ladder of employer duties: from 26°C the employer should act, from 30°C it must take effective measures, and at 35°C a room is legally unsuitable for work without special protections (Technical Rule ASR A3.5). The same framework sets minimum temperatures for the cold months. The rules are enforceable — through documented complaints, the works council and the occupational-safety authority — but expectations should be realistic: this is a field of pressure and process, not of walking out at 27 degrees.
The legal framework: ArbSchG, ArbStättV and ASR A3.5
The duty chain runs from the general obligation to protect employees’ health (§ 3 ArbSchG, § 618 BGB) through the Workplace Ordinance (ArbStättV), which requires a „gesundheitlich zuträgliche Raumtemperatur” — a room temperature not harmful to health. What that means in numbers is spelled out in the Technical Rule for Workplaces ASR A3.5 („Raumtemperatur”). The ASR is not a statute, but an employer who complies with it is presumed compliant with the ordinance — and one who ignores its values has to prove equivalent protection by other means. In practice, labor courts and safety authorities treat the ASR values as the operative standard.
Too cold: the minimum temperatures
ASR A3.5 sets minimum air temperatures by work intensity and posture. The key values:
- 20°C for light work performed seated — the classic office desk.
- 19°C for light work performed standing or walking.
- 17°C for moderate standing work, down to 12°C for heavy physical work.
- Washrooms and break rooms: 21°C.
If the heating fails, the employer must restore compliant temperatures within a reasonable span — mobile heaters, moving staff to other rooms, or temporarily releasing them. A brief morning dip while the heating ramps up is tolerated; a week at 15°C in an office is not.
Too hot: the 26 / 30 / 35 ladder
For heat, ASR A3.5 works in three steps:
- Above 26°C room temperature: the air temperature in work rooms „should” not exceed 26°C. Once outdoor temperatures pass 26°C and suitable sun protection exists, exceeding it is tolerated — but the employer should begin taking measures, and must do so where vulnerable employees work.
- Above 30°C: the employer must take effective measures. This is a hard duty, and its breach is what you document and escalate.
- Above 35°C: the room is unsuitable as a work room for the duration — unless the employer applies the special measures known from genuine heat work (air showers, cooling phases, protective equipment).
Typical measures, in the order the ASR prefers (technical before organisational before personal):
- effective sun shading (external blinds beat curtains),
- night-time cooling and ventilation regimes,
- shifting working hours into cooler morning slots — within the limits described in our article on maximum working hours,
- relaxing dress codes (no tie and jacket at 31°C),
- fans and, where feasible, mobile cooling units,
- providing drinks — obligatory above 30°C in practice.
No Hitzefrei — what you can and cannot do
There is no threshold at which employees may simply stop working. A right to refuse performance (Zurückbehaltungsrecht, § 273 BGB in connection with § 618 BGB) exists only where the employer persistently ignores its duties and the conditions pose a concrete health hazard — a high bar that courts assess after the fact. An employee who misjudges it risks a warning or dismissal for refusal to work.
Vulnerable groups: the thresholds shift
The ladder above describes duties toward healthy adult employees. For vulnerable groups the duties tighten well below 30°C:
- Pregnant and breastfeeding employees: the Mutterschutzgesetz requires an individual risk assessment; heat is a recognised hazard, and adjusted hours, cooler rooms or paid release can be required.
- Older employees and those with cardiovascular conditions or relevant medication: the employer’s risk assessment (Gefährdungsbeurteilung) must account for them individually.
- Home office as accommodation: where the office bakes and the job allows it, temporary remote work is an obvious measure — the legal framework is in our article on home-office rights.
Enforcement: the escalation path
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Measure and log
A simple thermometer, readings at fixed times, dates, room, outdoor temperature. A two-week log is worth more than any indignant email.
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File a Gefährdungsanzeige
A written hazard notification to the employer: temperatures, effects, request for measures, deadline. It creates the record and shifts the risk of inaction to the employer.
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Involve the works council
Health protection is a core co-determination right (§ 87 Abs. 1 Nr. 7 BetrVG). A works council can force binding heat rules through, if necessary via the Einigungsstelle.
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Complain to the Arbeitsschutzbehörde
Employees may complain to the occupational-safety authority if the employer does not remedy documented breaches (§ 17 Abs. 2 ArbSchG) — and may not be disadvantaged for it. Inspections tend to produce sudden budget for blinds.
Worked example
A call-center employee in Bonn, €2,900 gross per month, works in an open-plan office under a flat roof. During a heat wave the room log shows 31–33°C on ten consecutive working days; the employer’s response is a crate of water on day six. She files a Gefährdungsanzeige with the temperature log and involves the works council, which invokes § 87 Abs. 1 Nr. 7 BetrVG. Within a week the employer rents two mobile cooling units (about €1,800 for the season), moves shift starts to 7:00 and relaxes the dress code — a total outlay far below the cost of a single authority inspection or one week of heat-driven sick leave across a 60-person floor.
A colleague on the same floor chose the other route: he left at midday on the third hot day, announcing „this is illegal anyway.” He received a termination for refusal to work. In the subsequent Kündigungsschutzklage we negotiated a settlement of €5,800 (about two gross months) — the dismissal was disproportionate without a prior warning, but his refusal right was shaky because nothing was documented and the employer had not yet been formally notified. Same office, same heat: process made the difference.
Frequently asked questions
Is 26°C a hard legal limit?
No. Above 26°C the employer „should” act; the hard duty begins above 30°C, and 35°C makes the room unsuitable without special measures. But for pregnant employees and other vulnerable groups, concrete duties can arise well below 30°C.
If the employer sends everyone home, is the day unpaid?
No. If the employer closes the workplace because it cannot provide compliant conditions, it bears the risk: pay continues and the hours are not owed back.
Can the employer insist on the full dress code in the heat?
Relaxing dress codes is one of the listed heat measures, and where a works council exists, dress rules are co-determined. An employer that enforces jackets at 32°C while taking no other measures is building the file against itself.
What about the temperature in my home office?
For genuine telework arrangements the ArbStättV applies to the home workstation in reduced form; for occasional mobile work it largely does not. The employer’s general duty of care remains, but enforcement is weaker — the practical lever is usually agreeing flexible hours during heat waves.
My office sits at 17°C because the landlord won’t fix the heating. Can I refuse to work?
Same discipline as with heat: document, notify, escalate. The landlord dispute is the employer’s problem, not yours — it must provide compliant rooms, mobile heaters or alternative arrangements. Refusal remains the documented last resort.