BIOCLIMATIC ARCHITECTURE & PASSIVHAUS

Between them, buildings and the construction sector consume 36% of the planet's energy and produce 39% of CO₂, emissions, according to a report by the International Energy Agency External link, opens in new window. (IEA), a body dependent on the Organisation for Economic Co-operation and Development (OECD). Therefore, the building industry's transition toward sustainability is crucial to mitigate the effects of climate change. This is where bioclimatic architecture comes in, which is applied both to infrastructure and buildings.

WHAT IS BIOCLIMATIC ARCHITECTURE. OBJECTIVES

Bioclimatic architecture is a way of designing buildings based on the local climate, with the aim of ensuring thermal comfort using environmental resources. They must also blend into their natural surroundings. This is nothing new, because it is fair to say that traditional architecture is intrinsically bioclimatic. All you need to do is look at the shapes of roofs and the sizes of windows in different countries and regions.

The main aims of bioclimatic architecture are to create healthy, comfortable homes for the inhabitants of these buildings, while respecting the environment. To do this, it is essential to avoid using polluting materials, ensure the wellbeing of local biodiversity and make efficient use of energy, building materials, water and other resources.

BIOCLIMATIC STRATEGIES IN ARCHITECTURE

Bioclimatic buildings are based on design and daily use strategies that contribute to reducing their energy costs. These are the most common:

 Bioclimatic, efficient design. Designing buildings that adapt to the local climate to minimise energy expenditure and resources used, avoiding leaks and wastage.

 Control and smart use of space. Buildings and their rooms should be of a suitable size as to optimise energy use.

 Sustainable materials. Sustainable materials like wood, stone, natural fibre and recycled materials minimise the impact of the building.

 Use of renewable energies. Bioclimatic buildings use different types of renewable energies — solar, geothermal, wind and hydraulic — to reduce their consumption.

 Use of smart materials. For example: window panes that automatically darken, tiles that store the heat of the sun and smart materials that repair themselves to lengthen their useful life.

ELEMENTS OF BIOCLIMATIC DESIGN

Bioclimatic buildings require the use of a series of elements and building techniques that help to reduce their energy consumption and environmental impact:

• The orientation, size, height, layout, and even the colour of these houses is planned before they are built to make the best use of energy.
• The buildings are kept compact to reduce their surface area, with the main windows face the to make the most of passive solar energy.
• The materials surrounding the outside of the house (walls, doors, roofs, etc.) must be properly insulated to avoid heat loss through transference.
• Ventilation systems ensure that the heat in the air that is removed from the building is transferred to the fresh air that is brought in through heat exchangers to avoid thermal losses.
• Water and plants are also important in hotter climes, using trees, climbing plans, vertical gardens, green roofs and other techniques to create cool areas that protect from the heat of the sun.
• Thermal accumulators such as heat exchangers and pumps make it possible to capture and store the heat generated by the heating system or the sun and avoid losses.
• The air tightness of the building is essential. Leaks through gaps should be minimal with respect to the total volume of the house.
• Thermal bridges must be avoided: edges, corners and joints must be created carefully to avoid heat loss through these bridges.
• Hygrothermal comfort can be achieved by efficiently controlling air currents, evaporation caused by the sun or by reducing condensation, particularly in warm climates.

ADVANTAGES OF BIOCLIMATIC ARCHITECTURE

Bioclimatic architecture and ecoefficient buildings are beneficial to both building companies and their users, as well as taking care of the environment and society at large:

 Saving on bills due to better energy management and integration with their surroundings.

 Optimal thermal comfort to keep temperatures stable in any climate and season of the year.

 A lower carbon footprint due to reduced greenhouse gas emissions (GGE) and water footprint by optimising water consumption.

 Less noise pollution by using insulation.

 Improved sustainable habits by making sparing use of energy and other resources.

 Investment in innovation by using installations including aerothermal heating, renewable energy and electrical self-consumption.

WHAT IS A 'PASSIVHAUS' OR PASSIVE HOUSE

You can build a house with bioclimatic criteria, but you can go even further and build a passive house. This construction standard of German origin covers not only adapting the house to the climate, but also internal energy consumption itself so that the building needs as little energy as possible for heating and air conditioning. Some of the basic features are listed below:

​​​​​​​  SEE INFOGRAPHIC: The basic features of a passive house (passivhaus) [PDF] External link, opens in new window.

The Passivhaus Institut publishes a list of specifications with which passive houses must comply to obtain certification. These include the following:

• Use no more than 15 kWh/m² per year for heating and cooling. If the latter is essential, in warmer climes, for example, an additional margin is allowed for dehumidification.
• Use up to 60 kWh/m² per year of total primary energy, in other words, that used for heating, hot water and electricity.
• Thermal comfort must be available in all inhabited areas, in winter and summer alike, with a maximum of 10% of hours in the year above 25 °C.

Passive homes achieve these standards by making smart use of the main principles of bioclimatic architecture. It is estimated that there are more than 25,000 passive houses in the world, mainly in Germany, Switzerland, Austria and the Scandinavian countries.