Retrofitting balcony doors from the 1950s: feasibility study of VIPs
Other conference contribution, 2022

By combining necessary renovation measures with energy efficiency retrofitting measures, there is potential for energy savings and reduced carbon dioxide emissions. One benefit of these measures is the increased thermal comfort for the occupants in the building. In listed buildings, windows and doors are often parts that are difficult to impose energy efficiency retrofitting measures on because of the protection against changing the appearance of the building. Traditionally, balcony doors consisted of an upper glazed part and a lower opaque part, which was rarely properly insulated by the standards of today. The energy use for heating can be decreased by installing insulation in this lower opaque part of the door while increasing the thermal comfort. This study investigates a housing area from the 1950s with 220 balcony doors. The lower opaque part of the door today consists of a 12 mm thick sheet of porous wooden board. The study aims to evaluate if the thermal performance of the lower part of the door can be improved without changing its aesthetics. The improvement should be economically sound with a low environmental impact. Three different types of thermal insulation were compared; glass wool, expanded polystyrene (EPS), and vacuum insulation panel (VIP). The thickness of all materials was 10 mm. Calculations of the thermal, moisture, economic and environmental performances were done for the three materials. The results show that the EPS and glass wool have a payback period of 57 years, while VIP, due to the much higher thermal resistance, has a payback period of 17 years. Despite the higher investment cost for the VIP, this study shows that the material is beneficial due to its higher thermal resistance compared to conventional insulation materials.

vacuum insulation panel


energy efficiency



Jack Lahti

Chalmers, Architecture and Civil Engineering, Building Technology

Alexander Svensson

Chalmers, Architecture and Civil Engineering, Building Technology

Pär Johansson

Chalmers, Architecture and Civil Engineering, Building Technology

Proceedings of the 15th International Vacuum Insulation Symposium (IVIS2021)

15th International Vacuum Insulation Symposium (IVIS2021)
London, United Kingdom,

Subject Categories

Architectural Engineering

Building Technologies

Composite Science and Engineering

Driving Forces

Sustainable development

Areas of Advance


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