Mud bricks best for cool, green houses, says study

This article was first published on SciDev.Net, 28.06.17

Simple mud concrete bricks provide the most affordable and sustainable houses in the tropics, a Sri-Lankan study suggests.

Comparisons of four different types of walling materials revealed that mud concrete bricks have the lowest environmental impact and keep houses cool. They are also the cheapest, and easiest to dispose of once a house is knocked down.

Researchers compared mud concrete bricks with red bricks (modern fired clay bricks), hollow cement blocks and Cabook, the Sri Lankan name for bricks made from laterite soil, which are common in the tropics. The goal of the study was to find out which types of walling material are the most suitable for constructing affordable houses in the tropics, where population density and poverty are generally high.

“The sustainability of buildings and housing construction is essential to save lives and prevent inadequate living conditions.”

Christophe Lalande

“Why spend more money and destroy the environment more?” asks Rangika Halwatura, a civil engineer at the University of Moratuwa in Sri Lanka, and one of the authors of the paper.

Mud concrete bricks are made from soil in the same way as traditional mud bricks, but contain gravel and sand to improve their strength. The researchers looked at the carbon footprint of all four walling materials, and found that mud concrete bricks were the most environmentally friendly to produce and dispose of.

To check on thermal conductivity the researchers built one-square-metre model houses of the different walling types. Here, they found that red brick kept a house coolest, but mud concrete bricks performed almost as well.

Mud concrete bricks were also found to be the cheapest, at less than US$1,000 in Sri Lanka for an average-sized house, whereas red bricks cost nearly US$3,500.

Mud concrete bricks are widely used in other tropical countries but novel in Sri Lanka. They are popular because they are easy to make and therefore cheap, says Hurryson Moshi, a civil engineer in Tanzania. However, Moshi points out that as people grow wealthier they prefer the red bricks and cement blocks, as these are associated with higher socio-economic status.Walling material graph (FINAL)

Red Brick (modern fired brick), Cement (Hollow Cement Blocks), Cabook (laterite soil brick), Mud (mud concrete brick). Adapted from a graphic ©Udawattha and Halwatura, with permission. 

 

Moshi agrees with the study’s findings but says that other considerations, such as aesthetics, and symbols of modernity or social status, influence people’s choice of materials. Future studies should also take into account other sources of environmental damage such as deforestation (to produce timber to fire the bricks) or excavation of soil, he added.

In 2015, the government of Sri Lanka launched a programme to build 150,000 houses for the poor. This triggered the researchers’ idea to compare the different types of brick.

According to the United Nations, more than 850 million people around the world live in inadequate slum housing.

According to Christophe Lalande, leader of the UN-Habitat’s Housing Unit, poor neighbourhoods in developing countries are often the most affected by climate change and natural hazards such as storms and rising temperatures.

“The sustainability of buildings and housing construction, being adapted to the local environment, is essential to save lives or prevent inadequate living conditions,” he says.

Bigger isn’t better for energy savings

This article first appeared on Climate News Network, 19.05.17.

LONDON, 19 May, 2017 Advances made in the energy efficiency of heating and transport are lost because of people’s desire to have bigger houses and cars, two research papers have shown.

Researchers have found that houses in England, Australia, Canada, the US and New Zealand are getting bigger as people want more space and extra rooms. This means there is more air to be heated, destroying any climate benefits gained by better heating systems and more efficient insulation, they say.

The study, published in ScienceDirect, found that most house buyers struggled to understand the actual amount of energy their new home would use. Instead, they took information on energy efficiency as a yardstick for consumption.

This means house-owners may think their new, efficient home uses little energy, when in fact it may use more than their neighbours older, smaller houses, says Helen Viggers, a researcher at the public health department of the University of Otago in Wellington, New Zealand, and a co-author of the paper.

Implicit trade-off

“There is general knowledge in the public that both house sizes and insulation standards have increased, and a feeling that both of these are probably ‘good things’,” she told the Climate News Network. “But there is less understanding of the implicit trade-off in energy requirements with increasing house size.”

Viggers is critical of measuring energy usage by square metre, as this “immediately hides [the fact] that larger houses use more energy than smaller ones”.

The New Zealand team also found that larger, stand-alone dwellings featured more wasted” space – such as large lobbies, corner space and little-used hallways. They were designed in a less energy-efficient way than multi-home buildings or small houses.

The findings of the study mirror a 2016 paper by a team of scientists from the University of Barcelona in Spain. They compared Spanish car-buying habits with advances in the energy efficiency of engines, and found that, instead of actually saving energy, people would buy bigger and faster cars.

With little awareness of actual energy consumption,
people involuntarily increase their carbon footprint
while thinking they are helping the environment

The Spanish researchers found that fuel efficiency would have improved by 32% and 40% for petrol and diesel cars respectively, if the cars had stayed the same size. However, they learned that car weight increased by 31% for petrol cars and 26% for diesel between 1988 and 2015, meaning modern cars actually use more fuel than those from three decades ago, despite being more energy efficient.

The New Zealand researchers admitted they did not know whether increases in efficiency directly led to larger-sized consumer objects, or whether other factors influenced people’s buying decisions. But such consumer behaviour has dire consequences for the environment, both teams warn in their papers.

With little awareness of actual energy consumption, people involuntarily increase their carbon footprint while thinking they are helping the environment, Viggers says.

Attractive alternatives

She and her colleagues say policymakers and homebuilders need to come up with better, more attractive smaller homes, and should design some “stunningly good” smaller dwellings.

“They should make the maximum use of the space available, have appropriate room sizes and be aesthetically pleasing,” says Viggers, “so that buyers can see an alternative that might work just as well as a larger dwelling for their family.”

She also supports the creation of mandatory energy certificates that take into account actual consumption, and not just heating efficiency, which would allow those moving into a new home to “make a more informed decision about what that dwelling is worth”.

“Thermal modelling earlier in the design process also forces the designer and builder to explicitly choose the level of energy efficiency they want, and therefore the trade-offs they have to make,” she says. Climate News Network