This article describes the retrofitting of a five-family apartment building, implemented as a pilot and demonstration project for the Swiss Federal Office of Energy. The fact that this building on Mutschellenstrasse in Zurich is a listed building, imposes restrictions to the retrofitting process. However, the cellar ceiling, the roof and part of the building facade have been insulated, new windows have been installed and three apartments have been fitted with a mechanical ventilation system with heat recovery. Heating is provided by heat pumps.

Thermal comfort in a naturally ventilated test room is investigated. The test room is a lightweight portable cabin located in a sheltered area at Loughborough University, UK. Thermal comfort simulations were carried out for various sizes of openings and glazing. Medium and high thermal mass were added to the test room and their effects on thermal comfort were investigated. The results suggested that thermal mass has significant effect on thermal comfort parameters. Adding a 200 mm thick layer of medium-density concrete to the walls improved the thermal comfort over the summer by 40%.

A numerical model, employing a local-averaging formulation was developed for heat transfer and water vapor deposition within fiberglass insulation under air exfiltration and frosting conditions. Frost growth on the cold surface was modeled using special frost growth boundary conditions. Non-isotropic permeability effects that occur in fiberglass boards were included in the mode/for porous medium flow because tests showed that the permeability for flow parallel to the plane of the boards was 69% higher than perpendicular to the insulation boards.

This report presents a simplified computational model for combined air-, moisture and heat transport for one-dimensional cases. The model is based on finite difference technique with explicit forward differences in time. Analytical solutions for the coupling, the conductances, between the computational cells for a given air flow through the construction are used. Moisture is transferred by vapour diffusion and vapour convection. No liquid water transport occurs.