Future-ready Nordic Homes: Responding to the Changing Climate with Free-running Buildings

Abstract

The increasing urgency of climate change, coupled with the energy crisis and resource scarcity, demands radical and resilient building solutions. Buildings currently consume a significant portion of energy – in the Nordic context, primarily for indoor space conditioning – highlighting their vulnerability to future climate impacts.

Free-running buildings, operating without any energy for heating, cooling, and mechanical ventilation, relying instead exclusively on passive design strategies, arise as a potential countermeasure to this risk. The thesis aimed to evaluate the viability of free-running residential buildings in the Nordic region under contemporary and future climate scenarios. In the available scientific literature, knowledge of whole-year functional free-running buildings was quite limited.

A detailed case study of the Austrian free-running building „2226“ provided a basis for creating a model suitable for the selected six Nordic locations. Parametric simulations conducted in IDA ICE considered various materials of the building enclosure, internal heat gains, sensor-based control systems, and climate scenarios based on historic and present data, as well as the worst-case future climate projections. Parameters were modified to determine the impact of thermal transmittance, thermal inertia, and natural ventilation on building performance, which was assessed through the adaptive thermal comfort model, indoor relative humidity, and carbon dioxide concentration.

The findings demonstrated that in colder Nordic regions, insufficient internal heat gains during winter limited the viability of free-running buildings. However, in milder Nordic climates, free-running buildings could sustain comfort levels in cases of sun-facing window orientation, higher occupancy, and adequate natural ventilation. Future overheating risks were identified but could be mitigated by thermal inertia, particularly if high-mass materials were exposed on the interior building surfaces. Based on the results, simultaneous fulfillment of year-round requirements for thermal comfort and indoor climate solely through passive design measures in Nordic climates was proven challenging, especially during future extreme cold waves and heat waves.

The significance of this research lies in its contribution to the understanding of sustainable and resilient building practices in cold climates. While free-running buildings offer a promising approach to reducing dependence on energy consumption, their viability depends on the optimization of building design and certain occupancy patterns. Further research on hygrothermal behavior is warranted. The thesis paves the way for future exploration and development in the broader field of climate change adaptation.

Popular Abstract

Imagine a comfortable building that needs zero energy for heating. Here, in Sweden? No way! Unless..?
In this thesis, you can find out whether the so-called free-running buildings – using no energy for heating, cooling, or mechanical ventilation – could function in the Nordic countries, while still being healthy and comfortable.

Can free-running buildings function in the Nordics?
The results of computer simulations revealed that in colder parts of Nordic countries, free-running buildings struggled to maintain comfort during winter, simply because it was too cold outside. However, further down the south, these buildings might sustain comfortable conditions if the rooms receive enough heat from the sun and people living inside. In the south, there is also a risk of becoming too hot, but you can counter this partially by putting high-mass materials, such as brick or thick plaster, on the inside of your walls, floors, and ceilings. But generally, it would be hard to balance the criteria of comfortable indoor temperature and comfortable indoor humidity at the same time.

Will the functionality of a free-running building change with the changing climate?
To answer this question, the viability of the concept was studied for the past and present climates, and the worst-case future climate scenarios in the year 2100. In the „regular“ future, the average future global warming is taken into account, while in the „extreme“ future, intense cold waves and heat waves are included in the calculation. In extreme cases, it was shown that it would still get rather cold in winter, while in summer, heat waves will become much warmer, especially in the southernmost parts of the Nordic region. This means that the potential of the fully free-running concept might be limited to several months and not the whole year.

Why would anyone want a free-running building?
You should be aware that at this point, it is safe to assume that climate change will not be stopped or reversed. Increasing the adaptability and robustness of our buildings in the face of the coming crisis is therefore an important goal. We need to achieve more with less – in this case, for example, more warmth with less heating. Additionally, in the coming decades, we will probably experience many risks in the production, supply, and use of our energy, which is linked to how unsustainably we consume resources and pollute the planet. Wouldn't it be great if at home you didn't have to worry about meeting this (usually high) building energy demand because your house is thermally independent?

Has anyone ever tested the free-running concept?
Yes! In the thesis, you can read about an example of a real free-running building where it is never too warm or too cold inside, and the air is always fresh. It is located in Austria, where winters get quite cold. Nonetheless, people are happy to work there. In the context of Nordic climates, more research is needed to fully understand the behavior of free-running buildings.

How is this work important?
The findings of this thesis can be useful to building professionals who want to know more about the performance of passive building design in this part of the world, as well as to anyone assessing the impacts of climate change on the built environment. Hopefully, it can contribute to a better understanding of climate adaptation within the construction industry.

• author: Ljubas, Marko
• supervisor: Pieter de Wilde
• organization: Division of Energy and Building Design
• course: AEBM01 20241
• year: 2024
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• keywords: Free-running buildings, Climate change adaptation, Thermal inertia, Thermal comfort, Indoor climate, Passive building design
• language: English
• id: 9170924
• date added to LUP: 2024-08-22 15:51:01
• date last changed: 2024-08-22 15:51:01