Hybrid Ventilation Systems for Reduced Lifetime Emissions in Cold Climates

Abstract

Heating, ventilation, and air conditioning systems are notable sources of emissions in buildings. In cold climates, mechanical ventilation systems are characterized by significant initial embodied emissions but benefit from reduced operational emissions related to heating energy. On the other hand, natural ventilation systems have the advantage of lower initial embodied emissions but will use more heating energy, in cold climates, for the same atmospheric quality, due to the general lack of efficient heat recovery solutions. Hybrid ventilation systems are hybrids of these, using a combination of driving forces. This study utilized a life cycle assessment (LCA) to compare lifetime emissions of hybrid and mechanical ventilation systems in a Nordic climate. Findings suggest that hybrid ventilation systems can yield lower lifetime emissions, provided upfront emissions are reduced without significantly increasing energy consumption. Reduction potential in upfront emissions is more substantial in open landscape offices than classrooms due to higher person density in classrooms necessitating more fresh air, limiting reductions that can be achieved without thermal discomfort during the winter season. Our study shows the feasibility of reducing the carbon footprint of ventilation systems by employing hybrid climatization strategies.