Low energy buildings are highly insulated and airtight and therefore subject to overheating risks, where Ventilative cooling (VC) might be a relevant solution. 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 (State-of-the-art-review, Kolokotroni et al., 2015). VC is further an important topic supported by the International Energy Agency (IEA) - where the IEA Annex 62 has had a special focus on this area.
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 (Status and recommendations for better implementation of ventilative cooling in standards, legislation and compliance tools, Plesner, 2018).
The purpose of this task is to evaluate how well ventilative cooling is currently integrated into 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 national 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 the different countries, 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, which is why a workshop like this will be a way to discuss the findings from this study and hear people's views on if these recommendations could be used in their countries as well.
Results show that ventilative cooling is not explicitly addressed in all 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 many building legislation and compliance tools, design air flows are specified by the designer as fixed air flow rate. 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 objective of this topical session on "Better implementation of ventilative cooling in national building standards, legislation and compliance tools" is to give the participants an insight and discuss how well "Ventilative cooling" currently is integrated and used in EN, ISO and national standards, as well as in national legislation and compliance tools. There will be presentations based on national inputs for the status and recommendations for better implementation of ventilative cooling from 4 countries (UK, Italy, Switzerland and Denmark) with a special focus on natural ventilative cooling. The reason to focus on natural ventilative cooling is the fact that it is the area where we see the biggest compliance gap as calculation methods fully supporting e.g. wind and stack effects are not always present nationally, e.g. if too simplified methods are used for example only allowing the input of fixed air change rates.