1. THERMAL CONDITIONS, REVISION
Marianna Luoma
National Building Code of Finland: D2
Source: Seppänen, O. and Seppänen, M., Indoor Climate in Residential Buildings and HEPAC Technology, 1996

2. Indoor air temperature design value during the heating season is 21 ºC
National Building Code of Finland: indoor climate and ventilation of new buildings (D2)
Indoor air temperature design value during the heating season is 21 ºC
Acceptable range is ºC during the heating season; ºC outside the heating season

3. Temperature levels used in Finnish housing
Measurements carried out in 241 housing units in the Helsinki region
155 units in detached houses (including terraced houses)
87 units in high-rise buildings
Measurements made in November April 1989 (Ruotsalainen, R.)
Measurement period duration of two weeks per housing unit
Average value 21.8 ºC, variation range ºC
More than 50% of the units had a variation range of ºC

4. Temperature variation
Variation is caused, for example, by control equipment functions, thermal loads and external air temperature variations
Large temperature variations are experienced as unpleasant (especially in body areas between the head and ankles)
Structural heat capacity may be used to reduce temperature variations to a certain extent

5. Uneven thermal radiation
A room’s thermal conditions may be comfortable on average, but heat radiation may cause unpleasant fluctuations in thermal conditions
large windows
heaters, radiators
To be assessed by means of radiation temperature

6. Floor surface temperature
A cold floor surface cools the feet and may cause discomfort
The floor surface temperature may easily drop too low in cases where the floor borders with external air or with a semi-heated space.
When using normal footwear, the surface temperature for a person in the sitting position is 25 ºC, and 23 ºC in the standing position.
An applicable design value for floor heating is 29 ºC
Floor heating may cause problems through excessive floor surface temperature levels
In bathrooms, floor heating is experienced as a comfortable solution

7. Thermal conditions and building design
Massive wall structures attenuate the effect of external air temperature variations on indoor air temperature, during cold and warm seasons alike

8. Glass constructions
Large, sunny windows may cause extreme temperature levels in summer and a freezing sensation in winter

9. Internal thermal loads
Improved thermal insulation in wall construction has increased the effect of internal thermal loads on indoor temperature levels
Summertime temperature levels in workplaces may become excessive
A rise in indoor temperature may be prevented through mechanical cooling
FROM BUILDING HEATING 
TO BUILDING COOLING?