A new design method is proposed to calculate outdoor air ventilation rates to control respiratory infection risk in indoor spaces. We propose to use this method in future ventilation standards to complement existing ventilation criteria based on the perceived air quality and pollutant removal. The proposed method makes it possible to calculate the required ventilation rate at a given probability of infection and quanta emission rate. Present work used quanta emission rates for SARS-CoV-2 and consequently the method can be applied for other respiratory viruses with available quanta data. The method was applied to case studies representing typical rooms in public buildings. To reduce the probability of infection, the total airflow rate per infectious person revealed to be the most important parameter to reduce the infection risk. Category I ventilation rate prescribed in the EN 16798-1 standard satisfied many but not all type of spaces examined. The required ventilation rates started from about 80 L/s per room. Large variations between the results for the selected case studies made it impossible to provide a simple rule for estimating the required ventilation rates. Consequently, we conclude that to design rooms with a low infection risk the newly developed ventilation design method must be used.

Purpose - To provide input data to design and energy performance calculations of buildings and ventilation, heating, cooling and lighting systems. Design/methodology/approach - European directive for energy performance of buildings was approved in the beginning of 2003. The transition period is 3-6 years depending on the article. European Standardisation Organisation (CEN) has drafted several standards to help the member countries implementing the directive. One of these is the "Criteria for the indoor environment including thermal, indoor air quality (ventilation) light and noise." The standard has been developed based on existing international standards and guidelines for the indoor environment taken into account the latest results from published research. Findings - The standard specifies design values of indoor environment, values to be used in energy calculations, and methods how to verify the specified indoor environment in the buildings. The paper describes some of the principles used in standards, and gives examples presented in the standard. The standard covers all building types but the paper is focuses on the non-residential buildings, numeric examples are given only for offices. Research limitations/implications - The draft standard is under international review process during writing this paper, and subject to changes. The standard give default criteria for the indoor environmental parameters, which can be used if no national requirements are available. Originality/value - This paper describes the indoor environmental parameters, which are important for people's health, comfort and energy consumption of buildings. This will help users to select more uniform input data for energy calculations.