Low indoor temperatures are connected with a number of health issues and most people spend more than 90% of their time indoors.
| 18-24°C | The comfort zone, no risk to sedentary, healthy people |
| 16°C | Increasing risk of respiratory disorders |
| 12°C | Cardiovascular strain, increased blood pressure and viscosity |
| 9°C | Failing thermoregulation and risk of hypothermia, after two hours exposure as the deep body temperature falls. |
Decreasing indoor temperature below the comfort zone progressively influences the respiratory, cardiovascular and thermoregulatory systems and consequently the maintenance of good health.
The start of discomfort is likely to indicate the commencement of health risks, so that the temperatures required for comfort and for health are broadly the same.
For comfort and health, the temperature of the main occupied room should average 21°C. For other areas such as bedrooms, bathrooms and halls 18°C is recommended.
One group that may need higher temperatures is the sick and disabled. Restricted mobility inevitably results in more time spent in the home and the reduced level of activity means that a higher temperature is needed to achieve comfort.
An important point to note is that many very old people find it harder to detect temperature changes than other age groups. In some cases, temperatures of 15-16°C may not be experienced as ‘cold’ by the old person but will nevertheless be injurious to health.