Design curves for the application of night cooling ventilation.

A thermal simulation model and suitable weather data were used to generate design curves for the application of night ventilation cooling to office buildings. The work was carried out under the programme of the International Energy Agency (IEA) Annex 28 on 'Low Energy Cooling'. The generated curves show the potential reduction in internal peak day temperatures throughout the cooling season, the free cooling provided by night ventilation and the number of hours that a fan would run during the night for mechanical systems to achieve this free cooling. The advantages of using internal exposed thermal mass is clearly demonstrated in the graphs through the achieved temperature reductions, and the higher amount of free cooling available. However, they also demonstrate that night ventilation is a worthwhile cooling strategy to follow even in standard internally lightweight buildings.