The Oasis building has the honour of being the first passivhaus residential building in Murcia. This collective housing building is located in Murcia's old town. It has "Nearly Zero-Energy Consumption", high energy efficiency and sustainability with the internationally recognised passivhaus certificate.
The building consists of ten homes on four floors, garages and storerooms on the ground and basement floors. Modern and timeless, sober and elegant, this building is well integrated into the historic centre and, together with the garden, forms a true urban oasis.
"If we focus on the Passivhaus certification, we can see that, as initial sustainability criteria, this certification particularly stresses the need for energy efficiency. A highly efficient building has very low CO2 emissions and therefore pollutes less and protects the environment," says Antonio Fernández, architect of Alma Verde, the property's developer.
Over the years, Passivhaus buildings have used a specific construction system that has given them extraordinary results in achieving high energy efficiency with low energy consumption and emissions. These building systems, which are now copied by building regulations in different European countries, focus on the following criteria:
- Highly insulated envelope (façades, roofs and floors) with energy-efficient windows.
- Blower door test of the building to prevent unwanted draughts.
- Double-flow ventilation with energy-efficient heat recovery.
An efficiency test
The blower door test consists of a test whereby, at a pressure of 50 Pascals, which we achieve by installing a large fan in the entrance door, the company has to check that there are no unwanted air inlets or outlets. The operator uses smoke diffusers or infrared cameras to do this.
Double-flow ventilation is an installation that brings in clean air from outside and discharges stale air from inside permanently. This means all the air in the house is renewed every two hours. A heat exchanger is placed at the junction between the extract and supply air, which transfers the energy between the output and input flows with an efficiency of more than 85%.
"The passivhaus objective is to design a building to resemble a "thermos" that is fully insulated around its entire perimeter. In doing so, we manage to control the indoor-outdoor heat flow by using energy-efficient windows with solar protection elements," says Fernández.
The fully insulated building has virtually no unwanted draughts, meaning that, in principle, no air enters or leaves the building. The design is complemented by a controlled ventilation system that renews all the air in a house every two hours with virtually no energy loss, thanks to the heat exchanger.
"We, therefore, have the real "machine à habiter" Le Corbusier spoke of a century ago. Buildings have very low air-conditioning consumption, high comfort by maintaining constant indoor temperatures throughout the year and high indoor air quality due to frequent renovation and filtered air coming in from outside," says the architect.
In addition, this building has a centralised hot water system that heats the water through a combined aerothermal system and photovoltaic solar panels. It also has a lithium battery-powered lift that is mainly supplied by the energy from the solar panels.
A recirculation circuit was designed next to the domestic hot water installation to improve the water-saving system, activated by a push button. In this way, when the user needs to use hot water, they must first use the button located in the bathrooms, and in less than two minutes, they will have hot water in the shower or washbasin.
An investment in sustainability and housing's useful life
"A home is the most important investment we make in our lives and should have a useful life of at least 40 years. Today, there is no point in laying a brick that is not efficient and that does not take into account green materials, energy efficiency and construction systems to achieve more sustainable buildings with better levels of comfort and health and lower energy consumption," says Tamara Lemos, Head of Sustainable Construction at Triodos Bank.
From a market point of view – in the medium to long term – this type of housing will increase in value, and we'll see a growth in demand, according to the bank. "Throughout this year, we have become more aware of the need for efficient housing due to energy prices, but it is not just savings that are driving the change, but rather a greater commitment to the impact we have on the environment and how the environment affects people with higher temperatures, more polluted air that needs to be filtered or lower water and electricity consumption," adds Lemos.
Commitment to sustainability
"We have been financing sustainable construction in Spain for over 15 years because we're appeciate the sector's impact. We only support projects that have a positive impact on the environment and people's wellbeing. At Triodos Bank, we demand a minimum A rating in emissions and consumption, together with efficiency, which is fundamental to reducing consumption. We also take into account that the construction system incorporates the highest levels of health and comfort, as is the case with the passivhaus certification, which adds another qualitative element to housing and represents a milestone in our portfolio," explains the head of Sustainable Construction at Triodos Bank.
Regarding the higher cost usually involved in designing such a project, the bank's experience suggests that projects should be conceived as sustainable buildings from the outset, rather than modifying projects with a traditional profile.