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Thermal mass
What is night cooling?
Answer
Night ventilation is a low-energy strategy for cooling a building, providing a more comfortable environment for the occupants during hot daytime periods. It works by using natural or mechanical ventilation to cool the surfaces of the building fabric at night so they can absorb heat during the day
BRE Information Paper 4/98 describes the weather and building design conditions necessary for this technique to be applied successfully. The paper discusses suitable control strategies and the potential energy savings, some of which can be used for operating fans and other parts of the system. The principles of thermal mass (the dense structural elements such as concrete, brick and stone etc.) are explained in more detail in the BRE Digest 454 : Thermal mass in office buildings. This digest shows how increasing levels of thermal mass can reduce summer temperatures during the day. The greater the mass available to absorb heat during the day, the greater the cooling effect. During the night, windows may be left open or mechanical ventilation used to cool the exposed internal surfaces of the building.
Acknowledgement:
The Concrete Society
Other references:BRE Information paper 4/98 : Night ventilation for cooling office buildings
BRE Digest 454 - Part 2 : Thermal mass in office buildings : design criteria
BRE Digest 454 - Part 1 : Thermal mass in buildings - an introduction
