Economical impact of improved air quality in office buildings in cold climate

The annual energy cost and first cost of the HVAC system, life-cycle costs (LCC) and benefits of improved productivity were simulated in an office building located in a cold climate when improvements of air quality were made by increasing the outdoor air supply rate and by reducing the pollution loads. The building was ventilated by a variable air volume (VAV) system with an economizer or a constant air volume (CAV) system with heat recovery. The pollution loads were assumed to be similar to those in a non-low-polluting or low-polluting building. The costs were compared with benefits in improved productivity. The annual benefit due to improved air quality was always at least 14 times higher than the increase in annual energy and maintenance costs in a building with a CAV system, and at least 6 times higher when a VAV system was used. LCC showed that the simple pay-back time of investments for upgrading air quality was always = 2 years, and that the annual rate of return on investments was 4-5 times higher than the acceptable minimum rate of return. Although the present results include only direct benefits from productivity (excluding health and sickness absence costs), they already constitute a powerful argument for providing indoor air