Actual energy performance and indoor climate in Finnish NZEB daycare and school buildings

Abstract

The study addressed the improvement of building energy performance along with a good thermal comfort and indoor air quality (IAQ) in newly built Finnish daycare and school buildings. Indoor Environmental Quality (IEQ), calculated and actual energy performance, investment and life cycle cost (LCC) were monitored. Ventilation airflow rates, temperature, and CO2 were measured onsite in five daycare and school buildings during summer and winter, and an occupant questionnaire survey was conducted in parallel with onsite measurements. Energy performance was evaluated based on an energy performance certificate (EPC) and actual metered consumption to figure out possible performance gaps. Simulations were conducted to calibrate models and analyse improvements in ventilation system operation, which showed energy-saving potential while ensuring good thermal comfort and IAQ. The thermal comfort and IEQ of all buildings were excellent and were in line with the results of the questionaries survey except in ‘School 3’, which had specific odour and noise problems. The measured energy use of all buildings except ‘School 3’ was increased by a factor of 2.1–2.6 compared to the EPC value, caused by poor control of a ventilation system and the presence of some non-regulated uses such as hot kitchens, washing machines, and dryers. LCC considerably depended on actual energy use stressing the importance of accurate energy prediction. It was shown that the reduction of energy use by a factor of 1.9–3.1 is possible without compromising indoor climate by adjustment of correct operation hours, improving ventilation system control, and limiting excessive outdoor airflows in some cases.