Ventilation requirements based on carbon dioxide concentration criteria: implications on IAQ and energy use

Abstract

ABSTRACTMinimum airflow rates are either recommended or required based on the number of occupants, the intended use of the space or the floor plan area. This paper focuses on a new proposal for Spanish Technical Building Code based on limitations of the ventilation using the CO2 concentration as an indicator. The aim of the proposal is to introduce indoor air quality criteria in order to determine the design ventilation rates, and as a result, reduce the ventilation energy losses.Based on this proposal, the perceived indoor air quality in terms of the concentration of CO2 and other contaminants of concern is analysed through simulation. Maximum allowed area-based emission rates are defined for the indoor source contaminants. It was found that the minimum outdoor airflow rates based on maximum allowable CO2 concentrations would reduce heating demand by more than 25% when compared to the reference airflow rates. In addition, the influence of the airtightness of the envelope on the indoor air quality is analysed with regards to defining the corresponding maximum allowed area-based emission rates. As the envelope permeability increases, the maximum allowed area-based emission rates decrease for HCHO and total volatile organic compound, and should be around 27% lower comparing to the design case values.