Sunday, May 5, 2013

Green building techniques are cheaper

The first Passivhaus villa opened at Barwa City in Mesaimeer. The house has an ultra-low energy and super-insulated airtight design that requires little energy to cool, resulting in a reduced carbon footprint.
DOHA: Green building techniques are not only environmentally beneficial in Qatar but also economically viable, shows a cost analysis of the first Passivhaus (Passive House) in the country opened last week.
The analysis shows that eco-friendly methods may only require a relatively modest increase in capital costs for buildings, the Qatar Green Building Council (QGBC) said yesterday.
The first Passivhaus villa, along with a conventional villa, was constructed in Barwa City in Mesaimeer as part of an experimental project called Baytna, a joint initiative by QGBC, Kahramaa and Barwa Real Estate Group to study the benefits of the Passivhaus design in Qatar’s hot and arid climate.
“he project’s aim was to keep the inevitable uplift in capital costs required to comply with Passivhaus building standards to within 15 to 20 percent above those of the conventional villa. In less than eight months, the Passivhaus villa has been constructed to target with all the comforts of modern living, and with just a 16 percent increase in capital costs the villa is predicted to consume 50 percent less water and energy, and reduce carbon dioxide emissions by half,” said Dr Alex Amato, Head of Sustainability at QGBC.
Amato led the comparative cost analysis of the construction costs for the 225 sq m Passivhaus villa and its neighbouring conventional villa.
The main causes for increase in construction costs were increased thickness of insulation, triple glazing of window and door systems, high-efficiency lighting and advanced light control systems, as well as sun shading devices in the atrium.
The Passivhaus design is derived from a super-insulated airtight building envelope that requires little energy for cooling — an accomplishment that could greatly improve the environmental performance of buildings throughout the Gulf region.
The greatly increased level of applied insulation, along with triple glazed window and door systems, allow for much greater thermal insulation of the building envelope — requiring less energy for cooling, and reducing external heat gains.
LED and low-energy lamps have also been installed to minimise internal heat gains.
Meanwhile, advanced light control systems will improve energy efficiency through controls that switch off lighting when spaces are unoccupied and daylight sensors that prevent unnecessary artificial lighting.
Cost consultant Steven Humphrey of AECOM, one of more than 50 partners involved in the villa’s construction, said that Passivhaus villa’s reduced air conditioning load, which is roughly one third that of the conventional villa, was reflected in 1.4 percent savings in construction costs.
Amato believes that there is yet more potential to further reduce the capital costs of adopting Passivhaus standards for Qatar’s climate if ‘lean construction’ techniques are applied.
“If the design and construction processes from the onset sought to address ‘lean construction’ techniques, and if the project size was sufficiently large to permit economies of scale to be fully realised, then it is probable that the additional capital costs could be reduced to around or below 10 percent,” said Amato.
“New, but tried and tested, lean-construction techniques such as prefabrication and off-site manufacturing could be applied and these, together with sustainable procurement supply chain opportunities, could significantly reduce costs while improving the quality of future housing production that sought to adopt Passivhaus, or part-Passivhaus, standards,” he added.
Amato noted that the 16.1 percent additional cost excludes expenditure related to the other scientific experiments planned for the Baytna project, such as the production of renewable energy through photovoltaic arrays installed on the roof of the Passivhaus villa.
QGBC, Barwa Real Estate Group and Kahramaa have collectively established a scientific working committee to conduct extensive monitoring of the Passivhaus principles and low-carbon technologies being implemented.
A six-month period of testing and commissioning is now underway to compare each villa’s baseline performance without occupants.
Following this testing and commissioning period both villas will be occupied by similar-sized families, and further monitoring will take place for a year as a real life demonstration of environmental principles in practice.
The two families are expected to move into the three-bedroom villas by autumn 2013.