Effect of formaldehyde on ventilation rate and energy demand in Danish homes: Development of emission models and building performance simulation

Building performance simulation (BPS) tools need valid emission models to quantify the effects building generated pollution has on indoor air quality (IAQ) and energy demand. Predictions from existing emission models for volatile organic compounds have been shown not to correspond well with real world observations. This study aimed to approximate the impact building generated pollution has on the energy demand of Danish homes fitted with balanced mechanical ventilation systems using heat recovery. Two emission models were developed by regression analysis: one for normal level and one for high level formaldehyde (HCHO) emission rates. Data came from measurements done in detached and semi-detached homes in rural or sub-urban Denmark. Analysis included temperature, humidity and air changes per hour (ACH) as possible predictor variables. ACH was found to be the most important predictor. The emission models were implemented into a validated BPS tool, IDA ICE. Simulations showed it was necessary to have an ACH of minimum 0.22 h-1 to safeguard against HCHO. Two control strategies could prevent harmful levels of HCHO: a base level ventilation rate of 0.3 L/(s-m2) and a demand controlled ventilation (DCV) system using HCHO as a control variable. The DCV systems with heat recovery improved IAQ and reduced energy demand up to 3% seen relative to constant air volume ventilation systems with heat recovery. Based on considerations of the current level of technology and pricing, it was recommended to continue the current practice of prescribing base ventilation rates. Still, building generated pollution deserves continued attention.