Think of greenhouse gas (GHG) emissions and the first sectors that spring to mind are probably power generation and transport. However, according to the 2019 Global Status Report for Buildings and Construction, buildings accounted for 36% of final energy use worldwide in 2018 and 39% of energy and process-related carbon dioxide (CO2) emissions. This is a significantly higher proportion than power generation or transport – the latter comes in at 28% of final energy use and 23% of CO2 emissions. The report was prepared by the International Energy Agency for the Global Alliance for Buildings and Construction.
Across the world, more and more people live in urban environments. The proportion of the world’s population considered urban reached 55% in 2018. The UN expects this figure to rise to 68% by 2050. There are also more and more people. According to the UN, there could be another 2.5 billion people living in urban areas by 2050, which means more houses, offices, shops, restaurants and all the other building requirements that go with urban life. According to the Global Alliance for Buildings and Construction report, the energy intensity of space heating improved by 20% over the period 2010-2018, lighting by 17%, water heating by 9% and cooking by 8%. However, space cooling’s energy intensity rose by around 7%. Moreover, while water heating and lighting continued to improve in 2018 year on year, water heating, cooking and appliances saw no progression and space cooling’s energy intensity rose by 2.7%. As a result, GHG emissions from buildings are rising. Global buildings emissions increased 2% in 2018 for the second consecutive year and were 7% higher than in 2010, according to the report. Over the 2010-2018 period, the global population rose by just under 10% and the amount of floor space per person jumped 23%.
Buildings cause emissions in a number of ways. There are those generated from the machines and materials used in construction. Then there are the boilers and furnaces used for space heating, which might run on natural gas, heating oil or even coal. Water heating is another source of emissions, as is on-site power generation from diesel or gas-fired generators. These are direct emissions, but buildings also use a lot of grid electricity, the emissions of which depend on how the electricity is generated. A low carbon mix of renewables, natural gas and nuclear power will provide far fewer indirect buildings emissions than a grid system heavily dependent on coal, for example. Electricity use in buildings has leapt 19% since 2010. Indirect emissions account for a larger share of buildings emissions than direct emissions in both the residential and non-residential sectors. Consequently, power sector decarbonisation is a critical means of improving the emissions performance of buildings. Low carbon electricity from the grid can be used to replace direct emissions from fossil fuel use in buildings via electrification.
In addition, renewable energy sources, such as solar and ground source heat pumps, can provide clean energy on site.
Efficiency improvements are also an important means of reducing building emissions, but the direction of travel is not always positive.
According to the Global Alliance for Buildings and Construction report, the energy intensity of space heating improved by 20% over the period 2010-2018, lighting by 17%, water heating by 9% and cooking by 8%. However, space cooling’s energy intensity rose by around 7%. Moreover, while water heating and lighting continued to improve in 2018 year on year, water heating, cooking and appliances saw no progression and space cooling’s energy intensity rose by 2.7%. Although it only accounts for 6% of the total, space cooling has been the fastest growing use of energy in buildings since 2010, the report says. Overall, efficiency gains are not keeping pace with the expansion of urban environments and people’s desire for larger living areas.
However, some countries, states, cities and companies are getting to grips with the problem, aiming to eliminate building and construction sector emissions by 2050. For example, the Finnish capital Helsinki has pledged to be carbon neutral as early as 2035. Companies like Goldman Sachs, Grimshaw Architects and Grosvenor Group have all signed up to the World Green Building Council’s Net-Zero Carbon Buildings Commitment. The World Green Building Council aims to ensure that all new buildings and major renovations are net zero from 2030 and that all buildings are net zero by 2050.
A growing number of countries have established Green Building Councils. Governments are tightening building regulations and encouraging certification so that buildings’ emissions performance can be checked and verified. In January, 11 office buildings in the UK cities of Liverpool and Manchester became the first to be verified as net zero carbon under the UK’s Green Building Council’s 2019 definition based on their operational carbon emissions.
As the world’s population grows, achieving net zero in the buildings and construction sectors is undeniably a tough challenge, but one which must be met if the 2050 carbon targets adopted by an increasing number of countries are to be achieved. These, in turn, are designed to deliver on the goals of the Paris Treaty on Climate Change. It is a challenge which is already stimulating a huge amount of innovation and opportunity across multiple sectors from materials to architecture. Although yet to be widely deployed, companies are looking at everything from green cement and passive heating to the integration of solar power generation into the materials used to construct buildings. It is not impossible that the houses and office blocks of the future are net energy generators rather than net consumers.
Photo credit: shutterstock.com, Songquan Deng