Passive solutions to avoid overheating in your home

The current regulations promote improving thermal performance of buildings. To achieve this, it restricts the values of thermal transmittance of the opaque parts of the exterior enclosures and limits the openings of the facade based on the opaque-void ratio, orientation, climate zone, and internal load, in order to avoid overheating indoors. The new trend towards nearly zero-energy buildings makes it necessary to rethink the design and conventional construction techniques, following a more sustainable construction model. Below, we present four passive improvement solutions to reduce overheating without compromising the comfort of your home.

Solution 1: improve thermal performance of the envelope

If we increase the thickness of thermal insulation, we improve the thermal transmittance of the facade, which represents an energy improvement, as it decreases heating demand. It is estimated that a north-facing facade with 7 cm insulation increases its thermal transmittance by 13%. In the case of the roof, the improvement ranges between 3 and 4% for thicknesses of about 8 cm of extruded polystyrene.

But we should not only consider the insulation of opaque parts; we must also take into account improving the performance of the openings by increasing the air chamber of the glass, using low-emissivity glazing, and a minimum class 3 carpentry, taking advantage of the thermal inertia of materials to accumulate and regulate gains. We can reduce heating demand by up to 40% and cooling demand by 15% by installing airtight carpentry (class 3) that minimizes air infiltration.

Solution 2: solar control

To reduce cooling demand, we can decrease solar input by using radiation shields, both in the openings and opaque parts. To reduce both heating and cooling demand, we can take advantage of the benefits provided by thermal buffering spaces in the facade. It is estimated that a total demand reduction of 3% can be achieved in south-facing buildings and 5% in north-facing buildings.

Solution 3: solar accumulators

The use of solar accumulation strategies, such as glazing outdoor spaces (terraces), is a good solution in winter. However, in summer, if we want to avoid overheating these spaces, there must be the possibility of doing without part of this glazing (folding or sliding glass), as well as enjoying proper ventilation and an adequate solar protection system. It is also advisable to increase the thermal inertia of the facade to reduce total annual demand by increasing the weight of the envelope and the thickness of thermal insulation.

Solution 4: ventilation to avoid overheating

If we add a rate of internal ventilation to the energy performance improvement actions of the thermal envelope and solar protection, we can reduce the heating demand value by between 3 and 6 kWh/m² and cooling demand by 5 to 6 kWh/m², as well as achieve a considerable reduction in CO2 emissions. This translates to the following: with passive solutions, an energy rating B or A can be achieved.
Passive improvement strategies enable the distribution of indoor temperatures for a large part of the year, so active air conditioning systems are only necessary in specific cases without compromising interior comfort.