Overheating in the Nordics: challenges in the Swedish multi-residential building stock

Paper in proceeding, 2024

Overheating has not traditionally been an issue in Sweden and other Nordic countries. However, the record-warm summer of 2018 led to 700 deaths in Sweden, alarming the population and authorities. The Swedish Meteorological and Hydrological Institute projects that extreme heat events, previously occurring every twenty years, may happen every three to five years by the end of the century. This raises concerns for buildings without mechanical cooling, such as homes. The issue of overheating in Sweden requires therefore immediate attention.

To address this, a project was initiated employing a breadth of existing data resources, such as a large dataset of indoor and outdoor air temperature measurements from housing companies. This paper gives an overview of the challenges in the Swedish multi-residential building stock associated with overheating, via literature and statistics review and by analysing selected data from the warmest week in 2023. Data from one housing company were used for an overview (N=925 buildings). Two buildings in the sample were further selected for more detailed examination; one constructed in 1890 and one in 2016.

Among the identified challenges are the lack of requirements for limitation of overheating in new construction and refurbishment, a trend towards smaller and single-sided apartments and potential conflict between addressing overheating and access to daylight, which is highly valued in Northern Europe. Limited thermal adaptation of the Swedish population and sociocultural barriers are also discussed as important challenges.

The data analysis revealed variations in average daily indoor temperature between buildings, with a span of 7ºC (21-28ºC). The case study analysis showed that the 1890s building maintained overall acceptable indoor temperatures during the warmest week, while the 2016 building had a more severe issue. The project’s aim is to look at the relationships between different factors and provide short, medium and long-term solutions for new constructions and refurbishments.