A new study offers a glimpse of a villa that could help the UAE to achieve its net-zero energy targets without compromising on suitability for the extreme climate.
Design features such as shading, solar panels and an underground heat exchanger mean that if the building were to be constructed, the electricity that it took from the grid would be no more than the amount it supplied to the grid through generating its own power.
Using 3D printing could make the villa – which includes a majlis, a liwan leading into a central courtyard and a living area – less expensive to build than a standard villa if large numbers were produced, the new study suggests.
The design is created to be suitable as housing for Emirati families, and so hundreds or thousands of similar or identical buildings could be made.
Dr Tareq Abuimara, the study’s lead author and an assistant professor in the Washington State University School of Design and Construction, said that the building used “passive design” features from traditional UAE architecture to keep temperatures low.
“Most of the passive energies are taken from the vernacular [local or traditional] architecture, like increasing insulation or the thickness of the house, adding thermal mass to the house, using architectural shading. We’re trying to avoid heat from getting into the house,” said Dr Abuimara, who was an assistant professor at UAE University in Al Ain when the project started.
The UAE is committed to achieving net-zero emissions by 2050. As part of the plan, it plans to invest Dh200 billion ($54 billion) by 2030 to ensure energy demand is met while sustaining economic growth.
To help achieve the target, the UAE has started various projects and initiatives, such as the Mohammed bin Rashid Al Maktoum Solar Park, one of the world’s largest. The development will have a total capacity of 5,000 MW or five million kilowatts, and will reduce carbon emissions by 6.5 million tonnes every year when completed in 2030. This is just one portion of the Dh147 billion earmarked for investment into clean energy sources over the past 15 years.
Cooling down the house
The building uses a geothermal cooling system, which involves pipes that run underground. In summer, when the land underneath the villa is cooler than the outside air (because land underground heats or cools more slowly than the air), water or air can flow through the pipes so that the cooling effect can be felt in the house.
“Geothermal does not totally eliminate the mechanical cooling or heating, but it saves a lot,” Dr Abuimara said. “Let’s say I have air or water that has a temperature during the summer of 40-something. In the UAE, we pump some of this water through the soil so that it releases some of the heat to the cooler soil.
“Then, I will have my chiller or cooling equipment having to cool 28º water or air instead of 40º water or air. It’s a saving mechanism.”
While there would be an initial cost for creating the network of pipes, Dr Abuimara said that in the long run there would be financial savings and lower emissions.
Photovoltaic or solar panels on the roof of the villa would generate energy. At times of surplus, energy could be transferred to the grid. The villa is designed so that overall it does not take more electricity from the grid than it supplies to it.
The cost of 3D printing the villa would be much higher if a single unit were produced, but lower for each property if many similar villas were built.
The researchers’ calculations suggest the villa could cost as much as 20 per cent less than a villa produced using standard construction methods.
As well as 3D printing, the building design also makes use of hollow core concrete slabs, which have circular voids that reduce the amount of material used.
The design includes a central courtyard, which offers privacy to the villa residents and improves the natural ventilation.
Also involved in the project was Dr Madhar Haddad, an associate professor at UAE University, and four students – Alyazia Aldhaheri, Maitha Alzubaidi, Meerah Alyafei and Rauda Alderei.
The study, House of the Future: Designing a Net-Zero Energy Housing Archetype for Emirati Families, was published in Environmental Science and Sustainable Development last month.
Aside from the carbon emissions generated by operating buildings, the emissions from making building materials and from the construction process – the embodied or embedded emissions – are also a concern.
Prof Ljubomir Jankovic, author of Designing Zero Carbon Buildings: Embodied and Operational Emissions in Achieving True Zero, said that over time buildings with negative emissions – meaning that they supplied more power to the grid than they extracted – could cancel out their embodied emissions. This can take decades, although with some buildings the period is much shorter, depending on the balance between embodied and operational emissions.
Net-zero properties around the world included, he said, the Birmingham Zero Carbon House, a retrofitted terraced house in Birmingham in England built in 1840. The Floating Office Rotterdam in the Netherlands, and the new global headquarters of the American Society of Heating, Refrigerating and Air-Conditioning Engineers (Ashrae), a renovated 1978 building in the US state of Georgia, are other notable examples.
New material
The embodied emissions could be reduced, Prof Jankovic said, by using biologically derived materials, such as timber, straw bale, adobe (a mixture of clay and straw) and hempcrete (a bio-composite of hemp and lime).
“Bio-based materials help to reduce the starting emissions. But you can’t make a building completely out of these bio-based materials. You need to use some conventional materials,” said Prof Jankovic, who is professor of energy and buildings at the University of Salford in the UK.
He said that by maximising the use of bio-based materials, which have less embodied carbon, the amount of energy that the building needed to generate itself to achieve net zero over its lifetime was reduced.
According to Aaron Gillich, professor of building performance and policy at London South Bank University, while the use of low-carbon alternatives to concrete and steel should be maximised, such materials are more difficult to produce at the scale needed.
“The biggest commercial driver for this will be material efficiency,” he said. “In the past, we would just throw a lot of materials and energy at a project because it was quicker or easier than optimising the design.
“So, we’ve come a long way with this, and you can reduce construction costs and embodied carbon with good design and material efficiency, so this is a win-win.”
To make net-zero buildings more common, it may be necessary to develop business models in which developers benefit from using materials with lower embodied carbon.
“If the interests of developers and building users are aligned, then there’s no problem,” Prof Jankovic said. “If the developers can benefit from reduced energy bills over a number of years from a building, and therefore contribute to reduced carbon emissions, that would be a win-win.”
Net zero buildings can be more comfortable – because it is easier to keep temperatures to desired levels, such as through improved insulation – and cheaper to run, Prof Gillich said.
“It’s about giving people something better, not taking something away,” he said. “Net zero is an upgrade, not a compromise.”
