Quantifying the Impacts of Climate Change on the Hygrothermal Performance of Prefabricated Walls in Sweden

Abstract

Human activities accelerate climate variations which cause effects all over the world. The IPCC's Sixth Assessment report, which was released in 2021, shows that human activities have already warmed up the planet significantly. The report reveal that the climate has already increased by approximately 1.1 °C since the period 1850-1900 and the average temperature is predicted to exceed 1.5 °C within the upcoming decades. These changes will affect all areas of the earth. Studies reveal that climate change is expected to have significant impacts on buildings and many of the current buildings are not designed for climate changes and future extreme events. These extreme events will increase the costs and delays for the building sector and if buildings are not designed and prepared for such events, the damages and consequent costs will increase.

In this study, the impacts of climate change on the hygrothermal performance of four prefabricated wall types across three climate zones in Sweden are investigated. The study was conducted by utilizing the dynamic hygrothermal simulation tool WUFI, where moisture and heat simulations were performed. Three representative weather data sets have been used for Luleå, Stockholm, and Lund across two time periods (2010-2039 and 2040-2069). Each period contains three one-year data sets, including typical (TDY), extreme cold (ECY), and extreme warm years (EWY).

The results in this study show that by adding an insulation layer outside the wood studs, the RH levels in the woods studs decreases significantly. A wind-driven water leakage turned out having a significant impact on the studied walls, where a decrease of 10 % in the RH in the wood studs was detected when the water leakage was removed. When analysing the ACH in the air gap, the results consistently show that a low ACH leads to poorer moisture safety in all four wall types. Both WUFI simulated and hand calculated U-values reveals that the heat transmission through the walls varies throughout the assessed period. Even though the heat transmission varies in all four wall types, no significant signs of a degradation was detected, which likely depend on the high moisture resistance of the insulation material.

Popular Abstract

Human activities accelerate climate variations which cause effects all over the world. Investigations show that human activities have already warmed up the planet significantly and studies reveal that climate change is expected to have significant impacts on buildings. In this study, the impacts of climate change on four wall types are studied. The results show that by adding an insulation layer outside the wood studs, designing a tight building envelope and by providing a high air flow in the air gap, the moisture safety in the walls can increase.

Human activities accelerate climate variations which cause effects all over the world. The IPCC's Sixth Assessment report, which was released in 2021, shows that human activities have already warmed up the planet significantly. The report reveal that the climate has already increased by approximately 1.1 °C since the period 1850-1900 and the average temperature is predicted to exceed 1.5 °C within the upcoming decades. These changes will affect all areas of the earth. Studies reveal that climate change is expected to have significant impacts on buildings and many of the current buildings are not designed for climate changes and future extreme events. These extreme events will increase the costs and delays for the building sector and if buildings are not designed and prepared for such events, the damages and consequent costs will increase.

In this study, the impacts of climate change on the moisture- and heat performance of four prefabricated wall types across three climate zones in Sweden are investigated. The study was conducted by utilizing the dynamic hygrothermal simulation tool WUFI, where moisture- and heat simulations were performed. Three representative weather data sets have been used for Luleå, Stockholm, and Lund, including typical (TDY), extreme cold (ECY), and extreme warm years (EWY).

The results in this study show that by adding an insulation layer outside the wood studs, the moisture safety in the walls decreases significantly. A wind-driven water leakage turned out having a significant impact on the studied walls, where a decrease of 10 % in the relative humidity in the walls was detected when the water leakage was removed. When analysing the air flow rate in the air gap, the results consistently show that a low air flow leads to poorer moisture safety in all four wall types.

This study highlights the need for further research of building designs to improve constructions resilience to climate change. As the climate varies and changes, the design of constructions must be developed, and new innovations are needed. By further investigating crucial factors affecting the hygrothermal performance of building envelopes, severe damages and high costs can be avoided.

• author: Esfandiari, Nima
• supervisor: Vahid Nik
• organization: Division of Energy and Building Design
• alternative title: Calculating the Impacts of Climate Change on the Moisture- and Heat Performance of Conventional Wall Types in Sweden
• course: AEBM01 20241
• year: 2024
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• keywords: Climate change, prefabricated walls, hygrothermal performance, moisture safety, thermal degradation, energy use
• language: English
• id: 9165637
• date added to LUP: 2024-06-24 09:43:06
• date last changed: 2024-06-24 09:43:06