When considering a new home or building, developers and homeowners are often confronted with a choice: whether to retrofit an existing building, or tear it down and build a new one? Which one is better for climate change?
Among building energy experts, it is commonly understood that existing buildings, even after being upgraded for energy efficiency, cannot ever perform as well in terms of energy efficiency as a new building will. Therefore it seems that it should be better – in terms of overall energy-use – to build new rather than update existing buildings. However, due to the immense amount of greenhouse gases that get expended from manufacturing new building materials and transporting them, even the greenest new buildings have a greater impact on the planet than retrofitting existing buildings. While a new building may perform better in itself than a retrofitted building, the imbedded energy during construction far outweigh the increased energy savings.
In simpler terms, retrofitting older buildings is always better for the planet than building new ones.
A new study by the Preservation Green Lab of the National Trust for Historic Preservation found that retrofitting existing buildings is much better in terms of greenhouse gas emissions and amount of waste than state-of-the-art new ones. The study compares six types of buildings in several different cities, each with different climates. In every case, retrofitting existing buildings reduces the negative environmental impacts more than new ones. For example, a new state-of-the-art urban village mixed-use building in Chicago will take 42 years to have a better environmental impact than a similar retrofitted existing building. It takes 80 years in Portland, Oregon.
These findings contradict a common perception that new is always better, when in fact, more efficient use of existing resources emits less greenhouse gas. City planners and architects should be aware of the environmental ramification of building new, even if the new building is very green. Today, developers commonly knock down existing buildings just to construct a new building from scratch in the same location. Not only do all the materials from the existing infrastructure go to waste, but also the building has to be entirely re-constructed with new materials, all of which have imbedded energy costs.
Less often, developers will refurbish existing buildings, and usually only because they have historical significance. These old buildings have been proven to provide significant increases in energy performance after upgrades. For example, the Empire State Building in New York City (NYC) was recently retrofitted to improve its energy-use and building efficiency. After the renovation, the building is expected to reduce energy use by more than $4.4 million annually and cut carbon emissions by 105,000 metric tons over a 15-year period. The energy upgrade will pay itself back in just over three years, thanks to its 38 percent reduction in overall building energy use. The building achieved such huge savings largely through simple solutions, such as caulking gaps in the stone, spraying foam insulation around radiator pipes, and insulating the windows. What’s more, the building owner purchases 100 percent of the energy it does use from clean, renewable energy resources through Green Mountain Energy’s carbon offset program.
Upgrades like the one on the Empire State Buildings will become more common and more important in the years to come, especially in cities. In NYC alone, buildings account for 70 – 80 percent of emissions. In order for the city to reduce emissions and meet state targets, it will have to have much more energy-efficient buildings. Multi-family buildings can reduce utility costs by 15 to 30 percent in buildings with five or more residential units, according to the American Council for an Energy Efficiency Economy. Nationwide, that’s about $3.4 billion in savings. For NYC, which has a lot of multi-family buildings, the savings could be enormous. As the city grows, it will be important for developers to not only build energy-efficient buildings, but to also integrate them as best as possible to the existing infrastructure and resources already in hand.
As population grows in cities, new buildings will have to be built, so not every building can, or should be renovated. What is important for developers when constructing new buildings is to really consider the entire picture of what it means to be a sustainable building. Sustainability includes the overall footprint of the building, from its future energy demand, to its construction processes and material usage. Sustainability means looking at the big picture – all of the carbon emissions along the construction supply chain – and making the best choices for the ourselves as well as the planet.