The numbers don’t lie. To keep global warming at tolerable levels, the building industry has to change—radically and rapidly. That’s the message of a new report from the United Nations Environment Programme (UNEP).
The Global Status Report 2017 sounds a red alert: “near-zero-energy, zero-emissions buildings need to become the construction standard globally within the next decade” to ensure average temperatures rise no more than 2°C. Energy retrofits also need to become much more common.
The building sector is responsible for 39% of global carbon emissions, according to the report. That includes embodied carbon of building materials, and it makes the building sector the single largest contributor to global warming.
There is some good news, according to Brian Dean, coauthor of the report and an energy-efficiency expert at the International Energy Agency (IEA). “There are signs of progress on energy efficiency,” he told BuildingGreen, “but it’s not keeping up with the rate of growth.” Globally, we are adding new square footage so quickly that even major efficiency gains aren’t enough to bring overall energy use down.
Dean said energy use is declining worldwide from space heating, water heating, and lighting. But energy use from cooling, appliances, and electronic plug loads is growing fast as we see “more people, more homes, more buildings, and more wealth.”
Zero-carbon buildings and energy retrofits
The report calls for two major changes to help achieve the “two-degree scenario.” For new construction: net-zero-carbon operation. For existing buildings: energy-focused renovation. The report is replete with policy recommendations for how to get there.
Definitions of net-zero carbon differ, but in essence it means the building uses zero-carbon energy sources to make up for all of the structure’s carbon emissions over the course of a year. For example, photovoltaics on the site could make up for the carbon emissions of energy supplied from the grid.
For existing buildings, the report calls for the rate of energy retrofits to double or even triple in the next decade. Since there are so many existing buildings in the developed world, they should be the primary focus there, according to Dean. In the developing world, zero-carbon new construction is more urgent.
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