Cooling of existing buildings

Recommendation 85
Measures against incoming solar heat

Chapter (theme)
Architectural spaces (temperature)

Because of
sensory sensitivity (warmth), stereotypical patterns: rigidity

In order to
contribute to the thermal comfort in order to create a better learning environment.

Elaboration
The theme temperature estimates that in roughly 40% of Dutch schools it is often too hot or (less frequently) too cold. This estimate squares with the statement of 45% of Dutch teachers who find the school regularly too hot. Such estimates are usually in general alignment which those in other developed countries.
Students with autism suffer more from this circumstance than others because many are unable to adjust their body temperature to the ambient temperature. This leads to unwell-being, even to those who don’t consciously experience this maladjustment.
For this reason it is important to take extra measures in order to keep the temperature in school within the range of thermal comfort. This can – among other things – be achieved by measures preventing solar heat on roofs, walls and windows to enter the building.

Suggestions for schools which aren’t up to standard are:

• a second ceiling immediately below the roof
• a second cavity
• transverse ventilation below the roof
• if necessary, better insulated attics
• if not present: double glazing.

Green roofs
An option which merits some elaboration because of its many advantages is that of ‘green roofs’. It is inspired by the NYC Department of Education Office of Sustainability et al’s ‘Guide to Green Roofs on Existing School Buildings’. It defines ‘green roofs’ as “a system of layers (primarily consisting of protective roofing membranes, growing medium, and vegetation) that is installed on a rooftop of a building.” The guide distinguishes a simple type, ‘extensive’, from the more expensive and complex ‘intensive’ green roofs with more elaborate plantings or vegetable gardens.

The main reason we mention them here is that they minimize “the trapping and retaining of the sun’s heat that is the hallmark of dark-colored impervious roofing material. This ‘heat island effect’ can be reduced by the evaporative cooling that occurs with a Green Roof.”

There are many other advantages of green roofs as well:

• rain water will mostly not enter the sewage system because it is absorbed by the plants and is evaporated
• roof life extension because (other) roofing material is subject to heat and ultra-violet light which causes constant thermal stress
• improved air quality: because of its natural cooling effects less pollutants are released and less energy is needed for artificial cooling
• educational opportunities, among others in the fields of biology and environmental science.

The guide gives a ‘feasibility study checklist’, including an assessment of the load capacity of the existing roofs, which may need to be replaced and stresses that, especially the extensive roofs “may be quite expensive, even cost- prohibitive.”

*

double glazing