Overheating assessment for apartments during average and hot summers in the Nordic climate

Figures & data

Table 1. Summary of the literature review on the overheating risk through field measurements.

Research	Climate	Country	No. of the cases	Measure parameters	Criteria	Period of measurement	Analyzed years
Lomas et al., 2021	Climates other than cold climates	UK	750 apartments and houses	Indoor temperature	Adaptive Static (CIBSE (26 °C/1%))	Whole summer	2018
Pathan et al., 2017			122 dwellings	Indoor temperature, relative Humidity	Adaptive Static (CIBSE (26 °C/1%))	Whole summer	2009; 2010
Vellei et al., 2017			55 dwellings	Temperature, humidity, CO2	Adaptive	Whole summer	2014–2015
Gupta & Gregg, 2020			4 apartment buildings (5 flats)	Indoor and outdoor temperature, relative humidity CO2 levels	Adaptive Static (CIBSE (26 °C/1%))	26 June–27 July	2017
Beizaee et al., 2013			207 apartments and houses	Indoor temperature	Adaptive Static (CIBSE (26 °C/1%))	Whole summer	2007
Mavrogianni et al., 2017			101 dwellings	Indoor temperature	Adaptive Static (CIBSE (26 °C/1%))	Whole summer	2007
Baborska-Narożny et al., 2017			18 flats	Indoor temperature	Static, BS EN 15251	Whole summer	2013
Sharifi et al., 2019		Australia	8 detached house buildings	Indoor temperature	Adaptive	Whole summer	2011–2015
Birchmore et al., 2017		New Zealand	3 houses	Indoor temperature	Static (CIBSE (26 °C/1%))	4 seasons	2011
Tamerius et al., 2013		US	327 dwellings	Indoor temperature, relative humidity		5–14 days of summer	2008–2011
(Laouadi et al., 2020)	Cold climate	Canada	_	_	self-defined method	_	_
(Maivel et al., 2015)		Estonia	100 apartment buildings	Indoor temperature, relative humidity	Static	Whole summer	2011; 2018
(Kotol et al., 2014)		Greenland	79 dwellings	Indoor and outdoor temperature, relative humidity, CO2 levels	(ISO7730:2005)	7 days of summer	2011

Figure 1. The cities in the Helsinki Region [43].

Figure 2. The changes in Finnish building codes over time.

Figure 3. The number and share of apartments in categorized design years.

Figure 4. The number of apartments in different apartment type categories.

Table 2. Statistics of the mean outdoor air temperature at the Helsinki-Vantaa weather station in summers (between May 15 and August 31) 1989–2021.

Percentile/Year	Mean temperature (°C)
Minimum	13.8 (the year 1993)
10th percentile	14.3
33rd percentile	15.3
50th percentile (median)	15.9
67th percentile	16.5
90th percentile	17.4
Maximum	18.3 (the year 2018)
Summer 2020	16.3
Summer 2021	17.4

Figure 5. Outdoor daily mean, maximum, and minimum temperature during the summers of 2020 and 2021.

Figure 6. Global radiation during the summers of 2020 and 2021.

Figure 7. The percentage of apartments with the maximum hourly temperature of the summer above 27°C, 30°C, and 32°C. 6,974 apartments in 2020 and 6,056 apartments in 2021 are analyzed.

Figure 8. Degree hours above 27°C, 30°C, and 32°C for 98% of the apartments during the whole summer of 2020 and 2021.

Figure 9. Degree hours above 27°C, 30°C, and 32°C for 98% of the apartments during the relaxing time (21:00–8:00) of the whole summer in 2020 and 2021.

Figure 10. Degree hours above 27°C, 30°C, and 32°C for different design year categories.

Table 3. Post hoc test results of statistically significant differences for degree hours above 27°C in different design year groups. (The values in the brackets are P-value results.)

2020
	Before 1977	1977–2003	2004–2009	2010–2011	After 2012
Before 1977	_	FALSE (0.15)	TRUE (<0.01)	FALSE (0.87)	FALSE (0.93)
1977–2003	FALSE (0.15)	_	TRUE (<0.01)	FALSE (1.00)	FALSE (0.06)
2004–2009	TRUE (<0.01)	TRUE (<0.01)	_	TRUE (0.04)	TRUE (<0.01)
2010–2011	FALSE (0.87)	FALSE (1.00)	TRUE (0.04)	_	FALSE (0.66)
After 2012	FALSE (0.93)	FALSE (0.06)	TRUE (<0.01)	FALSE (0.66)	_
2021
Before 1977	_	FALSE (0.78)	FALSE (0.82)	FALSE (0.19)	TRUE (<0.01)
1977–2003	FALSE (0.78)	_	FALSE (1.00)	FALSE (0.05)	TRUE (<0.01)
2004–2009	FALSE (0.82)	FALSE (1.00)	_	FALSE (0.06)	TRUE (<0.01)
2010–2011	FALSE (0.19)	FALSE (0.05)	FALSE (0.06)	_	FALSE (0.12)
After 2012	TRUE (<0.01)	TRUE (<0.01)	TRUE (<0.01)	FALSE (0.12)	_

Figure 11. Degree hours above 27°C, 30°C, and 32°C for different apartment type categories.

Table 4. Post hoc test results of statistically significant differences for degree hours above 27°C in different types of apartments. (The values in the brackets are P-value results.)

	1-room	2-room	3-room	4-room	5-room	6-room
2020
1-room	_	TRUE (<0.01)	TRUE (<0.01)	TRUE (<0.01)	FALSE (0.95)	FALSE (1.00)
2-room	TRUE (<0.01)	_	TRUE (<0.01)	FALSE (0.79)	FALSE (0.96)	FALSE (1.00)
3-room	TRUE (<0.01)	TRUE (<0.01)	_	FALSE (0.63)	FALSE (0.42)	FALSE (0.99)
4-room	TRUE (<0.01)	FALSE (0.79)	FALSE (0.63)	_	FALSE (0.80)	FALSE (1.00)
5-room	FALSE (0.95)	FALSE (0.96)	FALSE (0.42)	FALSE (0.88)	_	FALSE (1.00)
6-room	FALSE (1.00)	FALSE (1.00)	FALSE (0.99)	FALSE (1.00)	FALSE (1.00)	_
2021
1-room	_	TRUE (<0.01)	TRUE (<0.01)	TRUE (<0.01)	FALSE (0.08)	FALSE (0.91)
2-room	TRUE (<0.01)	_	TRUE (<0.01)	FALSE (0.97)	FALSE (1.00)	FALSE (0.99)
3-room	TRUE (<0.01)	TRUE (<0.01)	_	FALSE (0.65)	FALSE (1.00)	FALSE (1.00)
4-room	TRUE (<0.01)	FALSE (0.97)	FALSE (0.65)	_	FALSE (1.00)	FALSE (0.99)
5-room	FALSE (0.08)	FALSE (1.00)	FALSE (1.00)	FALSE (1.00)	_	FALSE (1.00)
6-room	FALSE (0.91)	FALSE (0.99)	FALSE (1.00)	FALSE (0.99)	FALSE (1.00)	_

Figure 12. Degree hours above 27°C, 30°C, and 32°C for different area groups.

Table 5. Post hoc test results of statistically significant differences for degree hours above 27°C in different area categories (The values in the brackets are p-value results).

2020
	25 < area < 60	60 < area < 80	80 < area
25 < area < 60	_	TRUE (<0.01)	TRUE (<0.01)
60 < area < 80	TRUE (<0.01)	_	FALSE (<0.47)
80 < area	TRUE (<0.01)	FALSE (<0.47)	_
2021
25 < area < 60	_	TRUE (<0.01)	TRUE (<0.01)
60 < area < 80	TRUE (<0.01)	_	FALSE (<0.17)
80 < area	TRUE (<0.01)	FALSE (<0.17)	_

Lomas, K. J., Watson, S., Allinson, D., Fateh, A., Beaumont, A., Allen, J., Foster, H., & Garrett, H. (2021). Dwelling and household characteristics’ influence on reported and measured summertime overheating: A glimpse of a mild climate in the 2050s. Building and Environment, 201, 107986. https://doi.org/10.1016/j.buildenv.2021.107986

 Web of Science ®Google Scholar

Pathan, A., Mavrogianni, A., Summerfield, A., Oreszczyn, T., & Davies, M. (2017). Monitoring summer indoor overheating in the London housing stock. Energy and Buildings, 141, 361–378. https://doi.org/10.1016/j.enbuild.2017.02.049

 Web of Science ®Google Scholar

Vellei, M., Ramallo-González, A. P., Coley, D., Lee, J., Gabe-Thomas, E., Lovett, T., & Natarajan, S. (2017). Overheating in vulnerable and non-vulnerable households. Building Research & Information, 45(1-2), 102–118. https://doi.org/10.1080/09613218.2016.1222190

 Web of Science ®Google Scholar

Gupta, R., & Gregg, M. (2020). Assessing the magnitude and likely causes of summertime overheating in modern flats in UK. Energies, 13(19), 5202. https://doi.org/10.3390/en13195202

 Web of Science ®Google Scholar

Beizaee, A., Lomas, K. J., & Firth, S. K. (2013). National survey of summertime temperatures and overheating risk in English homes. Building and Environment, 65, 1–17. https://doi.org/10.1016/j.buildenv.2013.03.011

 Web of Science ®Google Scholar

Mavrogianni, A., Pathan, A., Oikonomou, E., Biddulph, P., Symonds, P., & Davies, M. (2017). Inhabitant actions and summer overheating risk in London dwellings. Building Research & Information, 45(1-2), 119–142. https://doi.org/10.1080/09613218.2016.1208431

 Web of Science ®Google Scholar

Baborska-Narożny, M., Stevenson, F., & Grudzińska, M. (2017). Overheating in retrofitted flats: Occupant practices, learning and interventions. Building Research & Information, 45(1-2), 40–59. https://doi.org/10.1080/09613218.2016.1226671

 Web of Science ®Google Scholar

Sharifi, S., Saman, W., & Alemu, A. (2019). Identification of overheating in the top floors of energy-efficient multilevel dwellings. Energy and Buildings, 204, 109452. https://doi.org/10.1016/j.enbuild.2019.109452

 Web of Science ®Google Scholar

Birchmore, R., Davies, K., Etherington, P., Tait, R., & Pivac, A. (2017). Overheating in Auckland homes: Testing and interventions in full-scale and simulated houses. Building Research & Information, 45(1-2), 157–175. https://doi.org/10.1080/09613218.2017.1232857

 Web of Science ®Google Scholar

Tamerius, J. D., Perzanowski, M. S., Acosta, L. M., Jacobson, J. S., Goldstein, I. F., Quinn, J. W., Rundle, A. G., & Shaman, J. (2013). Socioeconomic and outdoor meteorological determinants of indoor temperature and humidity in New York city dwellings*. Weather, Climate, and Society, 5(2), 168–179. https://doi.org/10.1175/WCAS-D-12-00030.1

 PubMed Web of Science ®Google Scholar

Laouadi, A., Bartko, M., & Lacasse, M. A. (2020). A new methodology of evaluation of overheating in buildings. Energy and Buildings, 226, 110360. https://doi.org/10.1016/j.enbuild.2020.110360

 Web of Science ®Google Scholar

Maivel, M., Kurnitski, J., & Kalamees, T. (2015). Field survey of overheating problems in Estonian apartment buildings. Architectural Science Review, 58(1), 1–10. https://doi.org/10.1080/00038628.2014.970610

 Web of Science ®Google Scholar

Kotol, M., Rode, C., Clausen, G., & Nielsen, T. R. (2014). Indoor environment in bedrooms in 79 Greenlandic households. Building and Environment, 81, 29–36. https://doi.org/10.1016/j.buildenv.2014.05.016

 Web of Science ®Google Scholar