Regulation for Heat Insulation in Brazil
Houses and other residential buildings are large consumers of electricity and gas. One of the ways to reduce the energy consumption in our homes is investing in heat insulation, which is still little explored in Brazil. In this article you will learn about the regulations that involve heat insulation in houses.
The low level of heat insulation in buildings turns out to be a major cause to the emission of millions of tons of CO2 and greenhouse gases. Degraded insulation in walls requires high gas consumption and electricity within the air conditioning of buildings. The electricity consumption in houses corresponds to 23% of the total energy consumed in Brazil, while residential gas consumption corresponds to 5.9%.
That is why in July 2013 new standards that set minimum criteria for heat insulation conditions in buildings were established. All construction projects developed from this date must follow the standards established by ABNT, short for Brazilian Association of Technical Standards. The standards do not apply to artificial temperature conditioning such as cooling or heating, all criteria were established based on natural conditions of sunlight and ventilation amongst others.
According to the standards, the basic components of the building comprising structures, walls and roofs must present fire resistance, heat insulation, acoustic insulation stability and impermeability appropriate to the function and size of the building.
Residential buildings must present minimum and maximum internal levels of temperature variation which are required according to each of the Brazilian bioclimatic zones defined by ABNT. There are 8 zones and each of them have several technical and construction recommendations in order to improve the buildings thermic conditions through better climate adaption.
Construction regulations that depend on the climatic zone have different ratings. The heat insulation of roofing and external walls can be classified as:
- Leve e isolada or light and isolated
- Pesada or heavy
- Leve e refletoras or light and reflective
These terms are related to the thermic characteristics of each element - to the transmission, retention and solar factor.
The heat insulation of open spaces such as windows and respective shading can be one of the following types:
- Medium with sunshine during the cold period
Medium and shaded
- Small and shaded
- Big and shaded
The terms small, medium and big refer to the percentage of the floor area in relation to the opening ventilation area. Shaded means the use of elements that protect the building from the sun, as small protective awnings on windows. Trees and pergolas can be used as shading options.
Thermic Conditions Requirements
ABNT established criteria regarding the thermic conditions of residential buildings that must be followed according to the required needs during the summer and winter.
Summer
The maximum daily air temperature inside rooms where people will spend long periods of time such as the living room and bedrooms must always be less than or equal to maximum temperature outside the building. This maximum temperature inside the house is calculated without the presence of internal heat sources like people, lamps and other equipment.
Winter
The minimum temperature inside rooms where people will spend long periods of time must always be higher than or equal to the external minimum temperature plus 3°C. These thermic conditions are required for the bioclimatic zones from 1 to 5 which are located in the South, Southeast, a small section of the Northeast and Central West. In the bioclimatic zone numbers 6, 7 and 8 located in the North and major part of Central West and Northeast, it is not necessary to follow these requirements in the winter.
Conditions for Heat Insulation
The walls and roofs between twin houses must provide fire resistance for a minimum period of 30 minutes, ensuring flames are contained in the building, heat insulation, stability and structural integrity. In the case of isolated housing units, 30 minutes fire resistance is required for roofs and walls that divide the kitchen and closed areas where gas equipment is located.
The insulation of external walls is not only a necessity for cold and mixed climates like the south of Brazil, it is also important for Brazil’s hot climates. Although the transmission of heat through the walls is much lower than through windows or roofs, it needs to be considered.
For Brazil’s hot climates minimum levels of wall insulation o must be 0.6 U, this is equivalent to a rigid plate of a high density heat insulating material with 50 mm thickness. For buildings in the Southern area of Brazil levels must be much higher with high density rigid plates of 10 cm thickness or more.