Graph of the Day: How buildings cut energy and emissions

According to the IEA, energy consumption in the global building sector accounts for around one-third of global final energy use, and produces about one-sixth of end-use direct CO2 emissions, having grown by 18 per cent between 2000 and 2010, to reach a whopping 117 exajoules (EJ).

But one of the more positive findings in the IEA’s Tracking Clean Energy Progress 2013 report, released on Wednesday, was that existing technologies offer significant potential to cut energy use in this sector and achieve deep CO2 emissions reduction.

In the report’s 2DS – the best-case scenario of limiting global warming to 2°C – the IEA predicts an increase in energy consumption by the building sector of only 6.6% from today’s levels to around
124 EJ in 2020, despite projected increases of 24% in the number of households and 21% in services floor area. And it says deep emissions reductions can be achieved at low cost based on existing technologies.

As you can see in the chart below, the IEA’s estimated 2DS building sector energy savings amount to 9.8EJ in 2020, while it predicts an emissions reduction of 511Mt of CO2.

The challenge, says the report, is to ensure appropriate policies are in place to realise this potential through energy savings in new and existing residential and commercial buildings; efficient heating, ventilation and air conditioning (HVAC) technologies; improved appliance and equipment efficiency; and energy-efficient lighting.

The report also points out that only China and the EU member states have mandatory building energy codes (BECs) that cover the entire building stock. In Australia, Canada and the United States, BECs
are voluntary at the federal level, but mandatory in some states or provinces. Chile, India, Korea, Russia and Tunisia also have mandatory codes, but these cover some elements of the building stock only.

As for performance-based BECs – the most advanced codes, which set absolute minimum energy performance requirements for building design and overall energy consumption of regulated loads (i.e. heating, cooling, ventilation, hot water and, in some countries, lighting) – they are only used by three countries in the world currently: Denmark, France and Tunisia.