The risk of overheating and energy demand of new and old Finnish apartment buildings in the cooling season

This study has compared the risk of overheating of a new and old apartment building in Finland and aimed to improve the indoor temperature conditions of the new apartment building using the passive strategies (sun shading, window opening, and window properties) and an active cooling system. So that seven different cases were defined and simulated. Regarding the results, the risk of overheating in the old building is significantly less than in the new building, and using new well-insulated windows with the same old wall construction in the old building, decreases the heating demand but has no significant effect on indoor air temperature. So that the windows are more important for energy usage but not for the indoor air temperature in the old Finnish apartment building during the summer period. Using openable windows would be the best passive solution for keeping the indoor air temperature of the spaces of the new building within the comfort limits with less than 10% of the time above the recommended temperature limits based on EN 16789-1 standard without any significant increase in heating demand. While Using an active cooling system in the living room of each apartment is the only solution that can provide thermal comfort for 100% of the cooling season in all the spaces including bedrooms.publishedVersio

Rakennusten kosteusvauriot ja ylilämpeneminen muuttuvassa ilmastossa – RAIL

Tutkimuksessa tehtiin laskennallisia tarkasteluja ulkoseinärakenteiden rakennusfysikaalisesta toimivuudesta nykyisessä ja projisoiduissa tulevaisuuden ilmastoskenaarioissa. Lisäksi laskennallisella mallinnuksella tarkasteltiin ilmastonmuutoksen vaikutuksia rakennusten ylilämpenemiseen ja lämpöviihtyvyyteen. Rakennusten kosteusvaurioiden ja niihin liittyvien mikrobien yhteyttä ihmisten terveyteen tarkasteltiin kahdella systemaattisella katsauksella. Korkeiden kesäajan lämpötilojen vaikutusta terveyteen nyt ja tulevaisuudessa arvioitiin epidemiologisin sekä vaikutusarvioinnin menetelmiin. Tehtyjen tarkastelujen perusteella suurin osa Suomessa yleisesti käytössä olevista ulkoseinä­rakenteista pärjää myös muuttuvassa ilmastossa. Homehtumisriski nousee sellaisissa ulkoseinärakenteissa, jotka päästävät viistosadetta lävitseen, pidättävät vettä rakenteen huokosverkostossa (tiili, läpäisevä betoni) ja tuuletus on heikkoa. Palvelutalojen sekä asuntojen laskennalliset ja havaitut lämpötilat nousevat korkeiksi jo nykyisessä ilmastossa. Pelkät auringonsuojausratkaisut eivät ole riittäviä pitämään huone­lämpötiloja riittävän alhaisella tasolla, vaan sen lisäksi tarvitaan myös aktiivista jäähdytystä erityisesti helleaaltojen aikana. Jäähdytys tulisi kohdistaa rakennuksiin, joissa asuu ikäihmisiä, sillä heillä terveysriskit ovat suurimmat. Ilman lisätoimia tulevat korkeiden lämpötilojen terveyshaitat huomattavasti lisääntymään Suomessa jo lähitulevaisuudessa väestön ikääntyessä.Tämä julkaisu on toteutettu osana valtioneuvoston selvitys- ja tutkimussuunnitelman toimeenpanoa. (tietokayttoon.fi) Julkaisun sisällöstä vastaavat tiedon tuottajat, eikä tekstisisältö välttämättä edusta valtioneuvoston näkemystä

The risk of overheating and energy demand of new and old Finnish apartment buildings in the cooling season

| openaire: EC/H2020/856602/EU//FINEST TWINS | openaire: EC/H2020/894511/EU//SUREFITThis study has compared the risk of overheating of a new and old apartment building in Finland and aimed to improve the indoor temperature conditions of the new apartment building using the passive strategies (sun shading, window opening, and window properties) and an active cooling system. So that seven different cases were defined and simulated. Regarding the results, the risk of overheating in the old building is significantly less than in the new building, and using new well-insulated windows with the same old wall construction in the old building, decreases the heating demand but has no significant effect on indoor air temperature. So that the windows are more important for energy usage but not for the indoor air temperature in the old Finnish apartment building during the summer period. Using openable windows would be the best passive solution for keeping the indoor air temperature of the spaces of the new building within the comfort limits with less than 10% of the time above the recommended temperature limits based on EN 16789-1 standard without any significant increase in heating demand. While Using an active cooling system in the living room of each apartment is the only solution that can provide thermal comfort for 100% of the cooling season in all the spaces including bedrooms.Peer reviewe

Indoor temperature conditions and energy demand of a Finnish detached house in a changing climate

| openaire: EC/H2020/855607/EU//FINEST TWINSThis study investigated the effect of passive strategies (orientation, thermal mass of building structure, window opening, and window properties) and the usage of an active cooling system on energy demand and indoor temperature conditions of a detached house in Finland in the current (TRY 2012) and future climatic conditions (2050). So that nine different cases were defined and simulated. The goal was to improve the indoor temperature conditions in the cooling season and analyze the effects of global warming on energy demand. Regarding the results of passive strategies, in the current climate, using openable windows would be the best solution for decreasing the cooling demand and providing acceptable indoor air temperature of the spaces. In this case, 96% of the time in the cooling season, the indoor temperature is below the maximum recommended indoor temperature (27 °C) of the thermal environment category III of the standard EN 15251 and EN 16798-1. While using an active cooling system in the hall of the upper floor, it is the only studied solution that can provide thermal comfort in all the spaces during the cooling season in both current and future climate based on the standards. In the future 2050 climate, the heating demand decreases much more than the amount of increase in the cooling demand. So that the total electricity demand of electrically heated detached houses in the future climate would be less than in the current climate.Peer reviewe

The risk of overheating and energy demand of new and old Finnish apartment buildings in the cooling season

| openaire: EC/H2020/856602/EU//FINEST TWINS | openaire: EC/H2020/894511/EU//SUREFITThis study has compared the risk of overheating of a new and old apartment building in Finland and aimed to improve the indoor temperature conditions of the new apartment building using the passive strategies (sun shading, window opening, and window properties) and an active cooling system. So that seven different cases were defined and simulated. Regarding the results, the risk of overheating in the old building is significantly less than in the new building, and using new well-insulated windows with the same old wall construction in the old building, decreases the heating demand but has no significant effect on indoor air temperature. So that the windows are more important for energy usage but not for the indoor air temperature in the old Finnish apartment building during the summer period. Using openable windows would be the best passive solution for keeping the indoor air temperature of the spaces of the new building within the comfort limits with less than 10% of the time above the recommended temperature limits based on EN 16789-1 standard without any significant increase in heating demand. While Using an active cooling system in the living room of each apartment is the only solution that can provide thermal comfort for 100% of the cooling season in all the spaces including bedrooms.Peer reviewe

Huonelämpötilan pysyvyys ja aktiivisen jäähdytyksen tarve tulevaisuuden ilmastossa

| openaire: EC/H2020/856602/EU//FINEST TWINS | openaire: EC/H2020/894511/EU//SUREFITTämän tutkimuksen tavoitteena on laskennallisesti selvittää, kuinka asuinkerrostalossa huonelämpötila ja jäähdytyksen tarve muuttuvat tulevaisuuden ilmastossa. Tutkimuksessa analysoitiin uusien ja 60- luvun asuinkerrostalojen lämpenemistä nykyisessä (TRY2020) ja tulevaisuuden ilmastossa (TRY2050). Lisäksi tutkittiin vuoden 2018 erityisen lämpimän hellekesän (HWS2018) ja siihen pohjautuvan ennustetun tulevaisuuden hellekesän (HWS2050) merkitystä asuinrakennuksien ylilämpenemiseen. Tutkimuksessa selvitettiin lisäksi olohuoneeseen asennetun jäähdyttävän ilmalämpöpumpun tehokkuutta ja energiankulutusta sekä nykyisissä että tulevaisuuden ilmasto-oloissa. Tulokset osoittavat, että uuden rakennuksen maksimilämpötila oli alhaisempi kuin vanhojen rakennuksien johtuen pienemmästä ikkuna-alasta ja paremmasta aurinkosuojauksesta. Nykyilmastossa uusien ja vanhojen rakennuksien maksimilämpötilat olivat noin 32 oC ja 35 oC. Sen sijaan keskimäärin kesäkaudella uuden rakennuksen lämpötila on korkeampi kuin vanhassa rakennuksessa. Hellekesän 2018 aikana tutkittujen rakennusten maksimilämpötilat nousivat jopa 35-38 oC:een. Tulevaisuuden ilmastossa (TRY2050 ja HWS2050) huonelämpötilat nousevat tästä vielä noin 1 oC:lla niin normaalikesän kuin hellekesän arvoihin nähden. Olohuoneeseen asennettu ilmalämpöpumppu on ainoa tutkittu ratkaisu, jolla voidaan pitää kaikkien huoneiden lämpötila alle 26-27 oC sekä nykyisessä että vuoden 2050 ennustetussa ilmastossa. Koneellinen jäähdytys lisää sähköenergian kulutusta tutkituissa kohteissa enimmillään vain 4 kWh/m2,a

The effect of local thermal sensation on overall thermal sensation in older people under warm conditions: a chamber room study

Global aging and climate warming have made scholars begin to pay attention to the thermal comfort of the elderly. The deterioration of the function of body organs and systems caused by aging affects the thermoregulatory system of the elderly, resulting in a narrowing of their thermoregulatory range. To ensure their thermal comfort, personalised thermal comfort systems can be used, for example. When designing a system or selecting equipment, the impact of local thermal sensation on the overall thermal sensation needs to be considered. Most of the existing studies are based on young people, however, the local thermal sensation of the elderly may not be consistent with that of the young. This study recruited 26 Finnish older adults to conduct a series of human thermal comfort experiments under warm conditions in a climate chamber. The local and overall thermal sensations of the elderly were analyzed, and the weights of the influence of different parts on the overall thermal sensation of the elderly were obtained. The study found that the head and torso had a greater impact on the overall thermal sensation in a warm environment.Peer reviewe

Effect of the urban microenvironment on the indoor air temperature of the residential building stock in the Helsinki region

| openaire: EC/H2020/894511/EU//SUREFIT Funding Information: This research was funded by projects HEATCLIM (Heat and health in the changing climate, Grant No. 329306 ) and HERCULES (Health, Risk and Climate change: Understanding Links between Exposure, hazards and vulnerability across spatial and temporal Scales, Grant No. 329241 funded by the Academy of Finland within the CLIHE (Climate change and health) program. SUREFIT (Sustainable solutions for affordable retrofit of domestic buildings) funded by the European Union (Horizon 2020 program, Grant No. 894511 ). Publisher Copyright: © 2023 The AuthorsDue to climate change, there is an increased risk of apartment overheating. In Nordic countries, heatwaves have not been common in the past and hence apartments are not equipped with mechanical cooling systems, so wise urban design might be a solution. This study evaluated the influence of the urban microenvironment on residential building indoor air temperature via green view index (GVI), floor area ratio and distance from the sea. We analyzed a large dataset of over 2000 apartments in the Helsinki region during summers of 2018 and 2021, where severe heatwaves were presented, and combined it with the aforementioned parameters. In the method used, closely situated buildings were clustered into groups by the microenvironment parameters. The results showed consistent correlations between clustered groups and microenvironment parameters, where the best-performing group had an indoor air temperature of about 1 °C lower than the average during the summers and 0.7 °C lower during the severe heatwaves. Building groups with higher GVI demonstrated a greater ability to endure long heatwaves, where combined influence of other urban microenvironment factors was significantly reduced. A substantial influence of sea distance and floor area ratio was observed during short heatwaves in the middle and late summer. The indoor temperature difference of the groups was compared to the average outdoor temperature difference of group areas based on the Finnish Meteorological Institute HARMONIE-AROME weather model implemented with the SURFEX module. The results revealed a consistent correlation between predicted outdoor and indoor temperatures and their distribution of group-to-area differences.Peer reviewe

Overheating risk and energy demand of nordic old and new apartment buildings during average and extreme weather conditions under a changing climate

| openaire: EC/H2020/894511/EU//SUREFIT | openaire: EC/H2020/856602/EU//FINEST TwinsThe global average air temperature is increasing as a manifestation of climate change and more intense and frequent heatwaves are expected to be associated with this rise worldwide, including northern Europe. Summertime indoor conditions in residential buildings and the health of occupants are influenced by climate change, particularly if no mechanical cooling is used. The energy use of buildings contributes to climate change through greenhouse gas emissions. It is, therefore, necessary to analyze the effects of climate change on the overheating risk and energy demand of residential buildings and to assess the efficiency of various measures to alleviate the overheating. In this study, simulations of dynamic energy and indoor conditions in a new and an old apartment building are performed using two climate scenarios for southern Finland,one for average and the other for extreme weather conditions in 2050. The evaluated measures against overheating included orientations, blinds, site shading, window properties,openable windows, the split cooling unit, and the ventilation cooling and ventilation boost. In both buildings, the overheating risk is high in the current and projected future average climate and, in particular, during exceptionally hot summers. The indoor conditions are occasionally even injurious for the health of occupants. The openable windows and ventilation cooling with ventilation boost were effective in improving the indoor conditions, during both current and future average and extreme weather conditions. However, the split cooling unit installed in the living room was the only studied solution able to completely prevent overheating in all the spaces with a fairly small amount of extra energy usage.Peer reviewe

Dimensioning of the cooling system in Finnish office buildings using the new cooling design days for the current and future climates

| openaire: EC/H2020/856602/EU//FINEST TWINS | openaire: EC/H2020/894511/EU//SUREFITThis study aimed to investigate the dimensioning cooling power demand in the current and future climate in office buildings, using the new cooling design days for Finland. The results showed that, depending on future climate scenarios, the dimensioning cooling power demand will increase by about 5–13% and 7–17% with the air-water and all-air system, respectively.Peer reviewe