Climate change wears down heavily on the built environment

Decisions made about building design and especially about infrastructure today have repercussions far into the future. Climate change affects the built environment, for example, by increasing wear on technical infrastructure and the external walls of buildings and by increasing the risk of flooding in certain areas. Climate change may also make built environments less attractive to residents at times. Negative effects may be mitigated by creating favourable microclimates by means of planning. The effects of climate change need to be taken into consideration in all aspects of construction, from land use planning to the positioning, construction, and life-cycle management of buildings. Clever infrastructure planning can counteract some of the negative effects of climate change and create attractive built environments.

Soil properties and areas prone to flooding may change

The most important direct effects of climate change on property development and land use relate to changes in soil properties and areas prone to flooding. The likelihood of ground frost decreases as winters become milder. The average depth of ground frost in snowless areas is likely to decrease by between 0.5 and 1.0 metres from current levels. The southern parts of the country will be the most affected. Due to variations in winter weather, buildings will nevertheless need to be protected against ground frost throughout the country even in the future, although the standards set on the level of protection may be revised. Water levels in the ground are likely to rise with heavier rainfall especially in the winter. This weakens the soil and reduces its ability to support the weight of infrastructure. Increasing summer droughts may also lower the levels of groundwater, which may cause subsidence. This kind of movement in the soil surface may damage pipelines especially in soils with high proportions of clay. Changes in the levels of moisture may cause acidification in water bodies in the acid sulphate soils found on the southwest and west coasts. [1]

The increasingly mild winters and heavier rainfall affect seasonal variations in water levels and change the volume and temporal distribution of flooding. Different water bodies and different parts of the country may be affected in different ways. Changes in areas prone to flooding affect the prerequisites of land use and property development. Rising sea levels and coastal flooding resulting from violent sea winds, which may increase with climate change, also have implications on property development in coastal areas. Heavier rains and the increasing likelihood of rainstorms may also increase local flooding far away from water bodies, if storm water systems are unable to cope with the increasing rainfall. Problems with storm water can be prevented by redirecting surface runoff to parks and other safe areas where permeability is high. [2] [3] [4]

Microclimates change and weather causes building wear

The microclimates found in built environments are important in determining how attractive an area is to residents. The attractiveness of living environments affects the well-being of residents and the amount of time they spend outdoors, for example. Climate change may have negative implications on the microclimates found in built environments at times, which needs to be factored into planning. Increasing windiness is one of the changes that may have a negative effect on the attractiveness of living environments, especially in coastal areas and in the winter. Increasing rainfall may also damage the attractiveness of living environments, although this may be remedied by introducing awnings and covered walkways, for example. The increasing likelihood of hot spells in the summer may make urban environments feel claustrophobic. This can also be solved by means of awnings and vegetation. [2] [3]

From the perspective of property development, the most important effect of climate change is rising winter temperatures. It may both benefit and harm the construction business. The decreasing likelihood of sub-zero temperatures facilitates concreting and foundation engineering, for example, while increasing rainfall creates problems on building sites with regard to storing materials, for example. Increasing windiness may also make work more difficult on building sites at times. Increasing temperature variations both below and above freezing may complicate the maintenance of buildings and other elements of built environments [1].

In general, the effects of climate change are more likely to increase the challenges of property development and the need for property maintenance than to decrease them. Especially the external surfaces of buildings are likely to suffer increasingly from wet and windy conditions as a result of climate change. Increasing rainfall is likely to increase rain loads by between 20 and 50 percent, and façades will be more and more susceptible to diagonal rain in windy weather. Low evaporation levels in the winter leave external surfaces wet for longer periods of time. There is a danger that external surfaces will deteriorate faster and require more regular maintenance in the future. [1]

Kerrostalon julkisivuremontti © Pirjo Ferin

Exterior renovation of a tower block in progress. Rainfall and windiness, which may increase with climate change, cause wear on the external walls of buildings.

Increasing temperature variations both below and above freezing is likely to increase weathering especially in Northern Finland. The number of days when temperatures hover around zero is likely to increase at first but to decrease as winters become shorter and shorter, first in the south and eventually also in the north [5]. Chemical weathering of concrete structures increases as temperatures and humidity levels rise. This may result in both structural and cosmetic damage in concrete façades. Corrosion in metal structures such as roofs is also likely to become increasingly common. [1] Other roof loads are expected to decrease with lower snowfall across the country. The water equivalent of snowfall may drop by more than 80 percent in the south [5]. Exceptionally snowy winters with large snow loads may nevertheless occur over the next few decades even in the southern parts of Finland, albeit less and less frequently.

The durability of infrastructure in the face of the seasonal variations of weather conditions in Finland is a major challenge, and climate change and the increasing likelihood of extreme weather phenomena will only exacerbate the problem. From the perspective of infrastructure, the most challenging of the gradual changes are those affecting soil moisture levels, as these may damage pipelines or cause corrosion in pipes and underground cables. [1] Soil acidity may also increase in places, which needs to be taken into consideration when building structures that have a long service life, such as district heating pipelines and bridge foundations [6].

Clever infrastructure design helps with adaptation

The importance of infrastructure design increases with climate change. The increasing risk of floods needs to be controlled by identifying the areas that are most vulnerable to flooding and discouraging property development in those areas, by imposing regulations on planning in high-risk areas, and by determining minimum heights from sea levels for buildings in each location. More detailed recommendations can be issued in connection with local and regional plans and local authority building regulations revised and supplemented as required. On a national level, a reform of the Finnish Land Use and Building Act and the Finnish Land Use and Building Decree may be necessary. The reform may involve identifying areas prone to flooding, imposing restrictions on property development in high-risk areas, or factoring in microclimates, topography, and soil characteristics, for example. New regulations may also be introduced on redirecting rainwater and surface water or on property development in coastal regions, including rules on minimum distances from shorelines and the height of buildings. [1] The easiest way to prepare for the effects of climate change is to factor them in when planning and developing new areas. Adapting existing buildings is always more challenging, especially if future adaptation needs have not been factored in by leaving space for protective structures and permeable surfaces, for example.

Favourable microclimates are important in determining how attractive an area is to residents, and climate change only serves to emphasise this. Attractive microclimates can be created by positioning buildings and vegetation so as to provide shelter from the wind, by designing sheltered outdoor areas, and by leaving enough room for green spaces. The effects of climate change on built environments can be controlled by clever microclimate design in communal gardens and public spaces and by creating covered outdoor spaces where possible. Green spaces amid infrastructure help to level out temperatures in the summer and provide shade in hot weather. They also provide shelter from the wind and increase the surface area where rainwater can be absorbed, which lowers the risk of flooding. Permeable surfacing can also be used in street and road structures to prevent localised floods. Drainage capacity may have to be increased in places due to increased rainfall. [1] [3]

References

  1. Ala-Outinen, T. Harmaajärvi, I., Kivikoski, H., Kouhia, I., Makkonen, L., Saarelainen, S., Tuhola, M., & Törnqvist, J. 2004. Ilmastonmuutoksen vaikutukset rakennettuun ympäristöön. (Impacts of climate change on the built environment. Abstract in English.) VTT, Espoo. VTT Tiedotteita 2227. 83 + 6 s. http://www.vtt.fi/inf/pdf/tiedotteet/2004/T2227.pdf
  2. Suomalainen, M., Vehviläinen, B., Veijalainen, N., Lepistö, A. & Mäkinen, R. 2006. Effects on the hydrological cycle – inland waters. In: Silander, J., Vehviläinen, B., Niemi, J., Arosilta, A., Dubrovin, T., Jormola, J., Keskisarja, V., Keto, A., Lepistö, A., Mäkinen, R., Ollila, M., Pajula, H., Pitkänen, H., Sammalkorpi, I., Suomalainen, M. & Veijalainen, N. 2006. Climate change adaptation for hydrology and water resources. FINADAPT Working Paper 6. Finnish Environment Insitute, Helsinki. Finnish Environment Institute Mimeographs 336: 5–13. http://hdl.handle.net/10138/41044
  3. Wahlgren, I., Kuismanen, K. & Makkonen, L. 2008. Ilmastonmuutoksen huomioiminen kaavoituksessa – tapauskohtaisia tarkasteluja. (Abstract in English.) Tutkimusraportti Nro VTT-R-03986-08. VTT. http://www.vtt.fi/inf/julkaisut/muut/2008/VTT_Ilmastonmuutos_kaavoitus_Loppuraportti.pdf
  4. Ministry of Agriculture and Forestry. 2005. Finland’s National Strategy for Adaptation to Climate Change. Ministry of Agriculture and Forestry, Helsinki. Publications 1a/2005. 280 p. http://www.mmm.fi/attachments/ymparisto/5kghLfz0d/MMMjulkaisu2005_1a.pdf
  5. Jylhä, K., Ruosteenoja, K., Räisänen, J., Venäläinen, A., Tuomenvirta, H., Ruokolainen, L., Saku, S. & Seitola, T. 2009. Arvioita Suomen muuttuvasta ilmastosta sopeutumistutkimuksia varten. ACCLIM-hankkeen raportti 2009. (The changing climate in Finland: estimates for adaptation studies. ACCLIM project report 2009. Extended abstract in English.) Ilmatieteen laitos, Helsinki. Raportteja 2009:4. 102 s. http://hdl.handle.net/10138/15711
  6. Saarelainen, S. 2006. Climate change and risks to the built environment. FINADAPT Working Paper 9. Finnish Environment Institute, Helsinki. Finnish Environment Institute Mimeographs 339. 22 p. http://hdl.handle.net/10138/41051

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