REPORT
Researchers make the map of thermal
discomfort in Portugal
discomfort in Portugal
Published on January 13rd, 2015
A study by the Universidade Nova de Lisboa, under the ClimaAdaPT.Local made a diagnosis to the thermal comfort of families in Portugal and the findings highlight the need to intervene by applying HVAC systems that enable, at the same time, the reduction of greenhouse gas emissions (GHG) and the adaptation of buildings to extreme events (heat and cold waves) in the future.
“Portuguese families are far from an acceptable thermal comfort, that the legislation foresees”, said Júlia Seixas, professor at the Faculty of Sciences and Technology of the Universidade Nova de Lisboa and researcher at the Center for Environmental and Sustainability Research (CENSE) on energy and climate.
The Buildings thermal performance regulation (RCCTE) considers as internal benchmarks temperatures of 25ºC in the warm seasons and 20ºC in the cooler seasons. Based on existing information on the buildings (type and date of construction, climate zone, HVAC equipment ownership, etc.), researchers evaluated the energy required to achieve these temperatures inside and, afterwards, crossed with the data provided by the Department of Energy on the final energy that is effectively spent for cooling and heating at the various municipalities under study.
“That distance gives us an indication of climatic discomfort that people go through. It's huge! There are people living in very unpleasant thermal conditions. We go very cold in Portugal”, laments Júlia Seixas.
his statement is supported by the Eurostat data obtained through the EU-SILC survey of 2012 where it is reported that Portugal is the third worst country in the European Union regarding the percentage of people who report not being able to keep their home adequately heated. In terms of cooling, and according to the same study, Portugal is the second worst country in the EU.
Data from the study of the Universidade Nova refers to 26 municipalities participating in the ClimaAdaPT project, under which they are outlining their coping strategies. Júlia Seixas has been present in some workshops with agents of local municipalities within this network.
“We were able to categorize, in the 26 municipalities, the most resilient and the most vulnerable. We have found a great interest from municipalities. I am sure that the authorities were much more alert to the subject of thermal comfort, which was never on the agenda. Municipalities can call onto themselves responsibilities to primarily meet the most severe cases, focusing on urban renewal”, she entrusts.
According to the researcher in energy and climate, some municipalities are even interested in deepening and going into detail about this analysis with a view to intervene in the most trouble spots, while fighting climate change.
The researchers went even further and crossed the temperature and energy consumption data with socio-economic characteristics, such as the level of literacy, age and the average household income. The study identifies the most critical parishes where the greatest thermal discomfort is allied with a greater percentage of the population over age 65 and less income. The implications in terms of health are obvious.
“It is no coincidence that the emergency becomes clogged during cold and heat waves”, continues the expert, recalling a forecast for the increase in this kind of events due to climate change.
Adapt and mitigate with a single measure
Based on this study, the goal is to act both at the level of adaptation and of mitigation of climate change effects using an appropriate approach to the building.
“We can, with the same type of solution, improve the thermal envelope of the building and consume less energy. If this is of fossil origin, it is possible to reduce CO2 emissions. At the same time, we are making the building more resilient to extreme weather events such as heat waves and cold waves, protecting the health of the population”, he believes.
The focus on indoor thermal comfort cannot be made, of course, at any cost. The very Decree-Law 80/2006, of 4 April (RCCTE) imposes limits on energy consumption for air conditioning and hot water production in a “clear incentive to use efficient systems and energy sources with less impact in terms of primary energy”.
Therefore, the approach of local authorities will have to take into account available low carbon options supported by endogenous energy resources (hydro, wind, solar, biomass), namely the installation of solar panels and the use of other renewable energy sources.
Examples in Bragança and Loulé
Everyone knows that living in Bragança or Loulé makes a difference in terms of useful energy consumption and for heating and cooling, first because of the outside temperature. But there are other factors to be taken into account when making calculations, for instance, the year of construction of the building and the type of apparatus used for air conditioning.
“In a simplified manner and with the weather conditions of the RCCTE regulations, it is estimated that an urban building previous to 1919, located in Bragança, has useful energy needs of about 253.3 kWh / m2.year to keep the indoor temperature at 20ºC during the heating season and 9.7ºC kWh / m2.year to ensure the 25ºC in the cooling season”, explains Julia Seixas.
A house in the same county built in1960-1980 would need a useful energy consumption of 440.0 kWh / m2.year for heating and 14.1ºC kWh / m2.year for cooling.
Further south, the bills are different. “Similar buildings in Loulé would need a substantially lower useful energy consumption: from 87.7 to 146.3 kWh / m2.year for heating and 19.5 to 9.6 kWh / m2.year for cooling, respectively for buildings prior to 1919 and houses built in 1960-1980”.
These values, the researcher claims, “reflect the differences in the construction characteristics of the building and the climate of the two municipalities. Currently, in Loulé, the warm season lasts five months, while in Bragança, it is eight months. The outside temperature during the cooling season in Loulé is around 23ºC and 19ºC in Bragança”.
Efficient appliances reduce energy consumption
Thus, “the useful energy consumption required to ensure the 20ºC with heating is translated into different amounts of final energy, depending on the type of air conditioning technology considered and its respective efficiency”.
For example, “in the case of the house in Bragança, the heating is ensured by a conventional fire with an efficiency of approximately 35%, with a final energy consumption of 1257.2 kWh / m2.year. If instead of the traditional fireplace, a fireplace with heat recovery is used, with a much higher efficiency (about 60%), the final energy consumption will be only of 733.4 kWh / m2.year”.
For the same house in Bragança, using a central heating with natural gas, we will have an even lower consumption, about 586.8 kWh / m2.year, given the greater efficiency of this equipment.
Nevertheless, she warns, “when considering CO2 emissions associated with heating, in the case of central heating with natural gas system, we have more emissions than with a fireplace (with or without heat recovery). For every kWh of natural gas consumed we have an associated emission of 0,202 kg CO2 while CO2 emissions from the combustion of biomass for energy production are not counted because the plants have absorbed CO2 during their growth”.
By: Cláudia Azevedo
The Buildings thermal performance regulation (RCCTE) considers as internal benchmarks temperatures of 25ºC in the warm seasons and 20ºC in the cooler seasons. Based on existing information on the buildings (type and date of construction, climate zone, HVAC equipment ownership, etc.), researchers evaluated the energy required to achieve these temperatures inside and, afterwards, crossed with the data provided by the Department of Energy on the final energy that is effectively spent for cooling and heating at the various municipalities under study.
“That distance gives us an indication of climatic discomfort that people go through. It's huge! There are people living in very unpleasant thermal conditions. We go very cold in Portugal”, laments Júlia Seixas.
his statement is supported by the Eurostat data obtained through the EU-SILC survey of 2012 where it is reported that Portugal is the third worst country in the European Union regarding the percentage of people who report not being able to keep their home adequately heated. In terms of cooling, and according to the same study, Portugal is the second worst country in the EU.
Data from the study of the Universidade Nova refers to 26 municipalities participating in the ClimaAdaPT project, under which they are outlining their coping strategies. Júlia Seixas has been present in some workshops with agents of local municipalities within this network.
“We were able to categorize, in the 26 municipalities, the most resilient and the most vulnerable. We have found a great interest from municipalities. I am sure that the authorities were much more alert to the subject of thermal comfort, which was never on the agenda. Municipalities can call onto themselves responsibilities to primarily meet the most severe cases, focusing on urban renewal”, she entrusts.
According to the researcher in energy and climate, some municipalities are even interested in deepening and going into detail about this analysis with a view to intervene in the most trouble spots, while fighting climate change.
The researchers went even further and crossed the temperature and energy consumption data with socio-economic characteristics, such as the level of literacy, age and the average household income. The study identifies the most critical parishes where the greatest thermal discomfort is allied with a greater percentage of the population over age 65 and less income. The implications in terms of health are obvious.
“It is no coincidence that the emergency becomes clogged during cold and heat waves”, continues the expert, recalling a forecast for the increase in this kind of events due to climate change.
Adapt and mitigate with a single measure
Based on this study, the goal is to act both at the level of adaptation and of mitigation of climate change effects using an appropriate approach to the building.
“We can, with the same type of solution, improve the thermal envelope of the building and consume less energy. If this is of fossil origin, it is possible to reduce CO2 emissions. At the same time, we are making the building more resilient to extreme weather events such as heat waves and cold waves, protecting the health of the population”, he believes.
The focus on indoor thermal comfort cannot be made, of course, at any cost. The very Decree-Law 80/2006, of 4 April (RCCTE) imposes limits on energy consumption for air conditioning and hot water production in a “clear incentive to use efficient systems and energy sources with less impact in terms of primary energy”.
Therefore, the approach of local authorities will have to take into account available low carbon options supported by endogenous energy resources (hydro, wind, solar, biomass), namely the installation of solar panels and the use of other renewable energy sources.
Examples in Bragança and Loulé
Everyone knows that living in Bragança or Loulé makes a difference in terms of useful energy consumption and for heating and cooling, first because of the outside temperature. But there are other factors to be taken into account when making calculations, for instance, the year of construction of the building and the type of apparatus used for air conditioning.
“In a simplified manner and with the weather conditions of the RCCTE regulations, it is estimated that an urban building previous to 1919, located in Bragança, has useful energy needs of about 253.3 kWh / m2.year to keep the indoor temperature at 20ºC during the heating season and 9.7ºC kWh / m2.year to ensure the 25ºC in the cooling season”, explains Julia Seixas.
A house in the same county built in1960-1980 would need a useful energy consumption of 440.0 kWh / m2.year for heating and 14.1ºC kWh / m2.year for cooling.
Further south, the bills are different. “Similar buildings in Loulé would need a substantially lower useful energy consumption: from 87.7 to 146.3 kWh / m2.year for heating and 19.5 to 9.6 kWh / m2.year for cooling, respectively for buildings prior to 1919 and houses built in 1960-1980”.
These values, the researcher claims, “reflect the differences in the construction characteristics of the building and the climate of the two municipalities. Currently, in Loulé, the warm season lasts five months, while in Bragança, it is eight months. The outside temperature during the cooling season in Loulé is around 23ºC and 19ºC in Bragança”.
Efficient appliances reduce energy consumption
Thus, “the useful energy consumption required to ensure the 20ºC with heating is translated into different amounts of final energy, depending on the type of air conditioning technology considered and its respective efficiency”.
For example, “in the case of the house in Bragança, the heating is ensured by a conventional fire with an efficiency of approximately 35%, with a final energy consumption of 1257.2 kWh / m2.year. If instead of the traditional fireplace, a fireplace with heat recovery is used, with a much higher efficiency (about 60%), the final energy consumption will be only of 733.4 kWh / m2.year”.
For the same house in Bragança, using a central heating with natural gas, we will have an even lower consumption, about 586.8 kWh / m2.year, given the greater efficiency of this equipment.
Nevertheless, she warns, “when considering CO2 emissions associated with heating, in the case of central heating with natural gas system, we have more emissions than with a fireplace (with or without heat recovery). For every kWh of natural gas consumed we have an associated emission of 0,202 kg CO2 while CO2 emissions from the combustion of biomass for energy production are not counted because the plants have absorbed CO2 during their growth”.
By: Cláudia Azevedo