“The most efficient house is the one that demands the least energy, not just the one that generates it through renewable energies,” says Fabián Garreta, our month’s guest on Natura Argentina´s Blog. Some tips to make a better use of the climate and energy in our homes.
There was a time when comfort needs were directly satisfied with architectonics resolutions. Those that could not be solved with construction was mitigated with clothing. If it was not enough either, a wider comfort range was tolerated. Since the middle of the last century, and in the framework of a sort of “world of cheap and abundant energy”, architecture has divorced from interaction with the environment and the heating and cooling systems that we know today began to multiply.
Currently, and beyond the final amount that we paid in the electricity, gas or network water bill, the cost of energy has been growing due to the constant increase in demand (growth of the world population and greater consumption) and the search for more environmentally sustainable solutions.
The construction and use or operation of buildings is responsible for about a third of greenhouse gas emissions. The highest energy consumption is in air conditioning: cooling and heating of living spaces.
In Argentina, this percentage is repeated, even with the demographic distribution highly favored by the climate. Construction quality in the country is deficient, since the building envelope is unable to take advantage of favorable environmental conditions (solar gain in winter and ventilation on hot days) and avoid harmful ones (thermal insulation, use of eaves and sunshades).
The need to achieve comfort, to rest, work or study, is beneficial for our health and to improve our quality of life. It is now widely established that the best conditions are achieved with temperatures between 18 and 26°C. If the architecture achieves a very good interaction with the climate, and the building reaches these temperature values, the energy demand to improve its habitability drops significantly.
THE PATH TO SUSTAINABLE HOUSING
Many variables involve a home to be sustainable. From the most basic aspects related to architecture and its way of living it, to the recovery of water, landscape design, the incorporation of efficient equipment or the implementation of renewable energies.
Maintaining or improving the level of comfort by lowering energy consumption is the great challenge. The most important factor when it comes to achieving an efficient home is to reduce the exchange of heat between the interior and the exterior, given that more than 60% of the energy consumed in the home is used for thermal conditioning (hot and cold). The most efficient home is the one that demands the least energy, not only the one that generates it through renewable energies.
Here are some tips (or bioclimatic design criteria) to keep in mind:
-Verify and, if necessary, correct the level of thermal insulation of walls, roofs and windows. Depending on the type of roof, it is more or less easy to add thermal insulation, there are solutions that rest directly on flat roofs and reduce heat loss to less than 1/3.
-Working on the walls is usually more complex, but we can use thermal plasters, insulation plates or coatings that allow us to incorporate greater control of the thermal flow between the existing wall and the new finish.
-The openings (the most thermally permeable elements), can be replaced by new ones with hermetic double glazing technology (DVH) and profiles with less conductivity and infiltration. If the budget is tighter, weather stripping can be applied to all openings, reducing the entry and exit of air, which greatly reduces the demand for air conditioning.
-Friendly materials: select materials with sustainability certification, such as the Floor-score or FSC in wood. Look for those that have recycled content and those that are produced near the work site, to reduce the impact of transportation. Nowadays, thanks to consumer demand, most companies show these qualities in the technical sheets of their products. For electrical appliances, select those with efficiency A or higher and look for robust equipment that requires less replacement.
THE FUTURE OF OUR HOUSES
There is a growing and unsatisfied demand for housing in Argentina that could be addressed from bioclimatic design and efficiency. Bioclimatic design should not be associated with construction with rudimentary materials (mud, straw, industrial waste). On the contrary, project and technological decisions must respond to the climate and ensure stability over time with minimal maintenance and energy use.
The implementation of the Distributed Generation Law, in force for some years now, can be a strategic instrument to decarbonize the existing and future architecture. Its application on a scale depends on the will of each government, but it is already an available and proven tool.
There are companies that sell materials with certifications that ensure a lower impact on the use of inputs and their production. Unfortunately, the construction market evolves very slowly in the hands of an unstable economy, which makes it difficult to create companies with a “green spirit”.
An excessive and misleading use of the concept of sustainability for commercial purposes can often be observed, as well as not very successful associations of the use of solar energy in architecturally very inefficient buildings. For example, sometimes, a solar system for hot water or photovoltaics is simply installed, and with that we believe that we are sustainable.
But in the last decades there have been regulations and legislation, especially in central countries, that require professionals to reach certain minimum values of energy efficiency in projects. In some cases, these requirements result in higher construction quality and less impact on the environment, even complying with standards of architectural excellence, such as LEED, Passivhaus, Breeam, EDGE Certification or others.
In Europe, it is common to find buildings that have an energy balance equal to zero. That is, during an annual cycle they consume the same as they generate. That is not the most advanced, there are buildings that even have an energy surplus: they produce more than they consume.
In Argentina, cities such as Rosario and Buenos Aires have regulations aimed at carrying out architectural projects with lower energy demand. All have the legal framework; however, its application is not yet effective.
The challenge of the future is in the application of bioclimatic design criteria: consider orientations, use of thermal insulation, natural ventilation, sunlight of interior spaces in cold seasons and sun protection in summer, etc. If we add to this the choice of efficient systems and installations, the use of energy for air conditioning equipment will be greatly reduced. Just by taking advantage of the sun as a source of heating in homes, Argentina would be saving more than 10% of primary energy.
Fabián Garreta is an Architect graduated from the UBA, with postgraduate training in bioclimatic design and renewable energies in the country and abroad. Category III MinCyT researcher, he carried out activities at the CIHE-FADU-UBA and the UTN-BA. He has taught courses on solar technology in architecture in different fields and made presentations at national and international scientific meetings. He is currently the owner of SURSOLAR (sursolar.com), a consultant for sustainability in architecture and the integration of renewable energies in buildings.