Home green home: The quickest carbon cutsBuildings gobble up almost half the world’s energy and spew out nearly a third of global greenhouse gas emissions. How can we reduce their impact?
Imagine for a moment taking all America’s cars and trucks off the road.
That would be the climate impact of green building, say consultants McKinsey & Co, who reckon that 520 billion dollars spent on building efficiency through 2020 would reduce U.S emissions by 1.1 gigatons every year.
Sounds expensive, but wait: That cash would also buy 1.2 trillion dollars of energy savings in a world facing rising prices and insecurity of supply. No wonder the Empire State Building in New York is going green. The retrofit should slash power bills by 38 percent.
And no wonder the U.S. and China put building efficiency at the heart of their climate plans, while Europeans are dumping wasteful lightbulbs and India is nurturing an eco-building revolution: In the campaign against global warming, green building promises quick wins.
On the other hand, if we do nothing our rapidly urbanizing world will double emissions from buildings by 2030. And because buildings are the biggest greenhouse gas emitters in most countries, this would make it impossible to prevent runaway global warming.
The building sector has the largest potential for significantly reducing emissions, says the Intergovernmental Panel on Climate Change (IPCC). Energy consumption could be reduced by 30 to 50 percent.
Incredibly, the IPCC says those savings could come at no extra cost. Many buildings need upgrading anyway, and energy-efficiency investments will pay for themselves by saving money on energy bills. And unlike carbon capture or geo-engineering, it can be done today, with proven technologies, many inspired by traditional architecture.
“The Romans did it,” points out Daniel Mill, senior consultant with Camco, one of the world’s biggest energy efficiency consultancies, “they cooled air coming into rooms by funneling it through ducts in the ground.”
Modern buildings by contrast spend 80 to 90 percent of their energy budget on cooling, heating, ventilation, lighting, and appliances.
In cold climates, better insulation of walls, roofs, floors, and windows is essential. Making buildings airtight, and orienting living areas towards the sun, also reduces heating costs.
In hot climates, better ventilation and protection from the sun are the priorities. Open plan designs help circulate air while roof gardens, thick walls, and shaded corridors reduce demand for air conditioning.
Energy-efficient appliances and lighting solutions, such as skylights, automated lighting, and low-energy bulbs, make a huge difference. Lighting accounts for around 17 percent of global energy consumption, according to Siemens Energy CTO Michael Weinhold.
Space and water heating/cooling systems must be more efficient. Gas-powered systems are cleaner than electric ones, but greener alternatives include geothermal heat pumps, biomass burners, air-to-water heat pumps, wood-burning, and solar-powered systems.
An even more efficient solution, says Daniel Mill, is to share energy. “Rather than each house having individual hot water boilers you have a shared boiler. Underground pipes distribute the water around the neighbourhood.”
The next step is to generate power locally. In Malmo, Sweden, they burn household waste to generate heat and electricity. By going off-grid they don’t lose energy in transmission. The houses are 40 to 60 percent more energy efficient than average European homes, says Mill, and only three percent of their waste goes to landfill.
From Malmo to Masdar City in the Arabian Desert, eco building is a hot topic. And there are plenty of standards to certify efficient and sustainable architecture: Australia’s GreenStar, Japan’s CASBEE, or the Leadership in Energy and Environmental Design (LEED) from the U.S. Green Building Council.
The problem is that the focus is on new buildings whereas the vast majority of buildings are old.
“Even in 2050, 80 to 85 percent of buildings will be buildings that are standing now,” says Mill. “We have got to do something about our existing stock.”
Some people are retrofitting old homes. In the U.S. homeowners can get 1500 dollar tax credits for making their homes more energy efficient. And in Germany, since 2004, homeowners have been able to get energy efficiency loans at preferential interest rates, reducing German emissions.
There are huge barriers, however.
First, buildings have extremely long life cycles. It is difficult to renovate them on the promise of energy savings in the distant future. The payback time for investments resulting in at least 20 percent reduced energy use ranges “from 15 to 25 years in existing buildings”, says the United Nations Environment Programme Sustainable Building Initiative (UNEP-SBCI).
Second, building users, who pay the energy bills, often don’t own the building so are unwilling to invest. The building owners, on the other hand, don’t pay the energy bills and so feel the same.
Third, politicians, lawmakers, and markets have not championed green building.
"Not a SINGLE suggestion (on the Bali Action Plan) from the Parties, including agencies and observers, covered the building sector," complained Kilaparti Ramakrishna, UNEP’s senior advisor on environmental law and conventions, in April 2009.
UNEP-SBCI points out that of 4500 projects in the Kyoto Protocol Clean Development Mechanism only 12 seek to reduce energy demand from buildings. “Market forces alone will not bring about emission reductions from buildings,” it concludes in a study that argues that government regulations such as building codes are more effective.
Some governments have made encouraging moves. The UK Carbon Reduction Commitment will from 2010 reward owners of commercial property for cutting energy use and penalize them for wasting energy. The Sustainable Buildings Code will require all new buildings to meet efficiency levels that will increase year by year.
There is also the European Union’s Energy Performance of Buildings Directive and the U.S. government’s Energy Star programme.
“We know it can be done, the technology is there,” concludes Daniel Mill. “We need architects and builders designing buildings to suit the climate and environment rather than just to make money.”