Status and recommendations for better implementation of ventilative cooling into Danish standards, building legislation and energy compliance tool

Ventilative cooling (VC) is an application (distribution in time and space) of air flow rates to reduce cooling loads in spaces using outside air driven by natural, mechanical or hybrid ventilation strategies. Ventilative cooling reduces overheating in both existing and new buildings - being both a sustainable and energy efficient solution to improve indoor thermal comfort. In new buildings VC, may save cooling energy and thereby make it easier to fulfil future energy legislation for buildings. VC is an important topic supported by the International Energy Agency (IEA) - where the IEA Annex 62 has had a special focus on this area.

Low energy buildings are highly insulated and airtight and therefore subject to overheating risks, where VC might be a relevant solution. One of the tasks of IEA Annex 62 has been to evaluate the current status and make recommendations for better implementation of VC in future standards, legislation and compliance tools for 11 different countries, incl. e.g. Denmark, Italy and Japan.

The purpose of this paper is to evaluate how well ventilative cooling is currently integrated into Danish national standards, legislation and compliance tools and thereby make future recommendations based on this.

The approach is to evaluate to which extent certain ventilative cooling parameters are integrated into Danish standards, legislation and compliance tools through questionnaires asking if e.g. cross ventilation is included, which calculation time step is used for thermal comfort and if the position of windows is taken into account. Based on the answers from the questionnaire a concise status was established for Denmark, conclusions were drawn and thereafter concrete recommendations were given.

The Authors hope that the recommendations found throughout the IEA Annex 62 activities will help and inspire policy makers, regulators and experts to improve future standards, legislations and compliance tools and better address natural ventilative cooling.

Results show that ventilative cooling is not explicitly addressed in Danish building legislation nor national standards. There is presently, among others, lack of information on how to use windows, night cooling possibilities, window control and automation. In Danish building legislation and compliance tool, design air flows are specified by the designer as fixed air flow rates split up into winter and summer operation. In reality air flow rates, especially from natural ventilation, are seldom or never constant and a recommendation could be to allow the possibility for variable air flow rates. The recommendation for better implementation of ventilative cooling in Danish standards could be to have more “design specific” standards providing guidance on how to achieve well-functioning ventilative cooling systems reducing overheating in buildings. The concrete recommendations should give inspiration to regulators when making future revisions of standards, legislation and compliance tools.