Which is Greener, Cheaper and Better for the Environment?
The process of new construction, with all of the advanced green building systems, is often faster than renovating an existing structure. But when you factor in having an existing building and infrastructure, which then has the biggest impact environmentally?While the ease of new construction might be preferred, the greater potential for reducing your carbon impact during a renovation compared to a new construction is very apparent over a 75 year life span of a home or building. The National Trust for Historic Preservation recently stated that the greenest building may be the one you already own.
A new building that is 30% more energy efficient than the average building could take 10 to 80 years to overcome the negative carbon impact that comes with new construction versus renovation. There is an immense amount of energy and CO2 locked into existing buildings from the foundation, materials, energy to make new materials, transport materials, etc. that provides a savings in carbon dioxide compared to the demolition (energy to destruct and haul away) of an existing structure and the creation of a brand new building.
CO2 emissions from homes or buildings include two distinct sources; “embodied” CO2 given off during the building process and the manufacture of the materials during the building of the home, and “operational” CO2 given off from the energy use of living in the building. Obviously renovating an existing building saves substantial CO2 emissions, but over a life span of 50 to 75 years there will be a crossover to where the 30% more efficient new building would save more CO2 emissions through energy savings. But the question is – are short term CO2 emissions more important than long term bigger saving, assuming everything else stays the same?
The building industry expects that 25% of the U.S. commercial building stock will be demolished before 2030. What if instead, we reuse these buildings and retrofit them to high efficiency within the existing building’s limitations? We have already made the CO2 investment in the “embodied” building so let’s reuse and retrofit as a major part of our overall strategy, and create jobs and economic development while reducing CO2 emissions.
New construction will always be a part of the building mix, but if we build to an advanced standard like LEED, Net Zero Energy and Living Building Challenge, we can beat that 30% theoretical operating savings for 50% to 100% reduction in “operational” CO2 emissions. The USA can’t afford to build to minimum standards but needs to build to advanced standards that have long term economic and environmental implications. Just imagine a future where existing buildings gain a new life at a higher “operational” efficiency and new buildings need to operate at a Net Zero Energy standard and have Zero energy “operational” CO2 emissions!
I always shudder when I am watching HGTV and they are renovating with sledge hammers instead of deconstructing, reusing, repurposing and donating materials saved to someone that needs a cabinet or window. We recently had a whole house renovation project and by deconstructing what was being redone we were able to give away: kitchen cabinets, 3 storm doors, all appliances, carpeting, ceiling fans and light fixtures. A second floor master bedroom was added on the garage and a sun room addition that reused 20 sheets of plywood, 30- 2X8s from the existing home and 3 patio doors from another building being renovated. Not only was there zero energy or CO2 emissions created from the reuse, but additional savings in transporting the building materials from a factory were also saved. The reduction in the construction waste headed to the landfill saved money, CO2 and gave the owners and builder a sense of pride. The existing home received new energy star rated windows with low-e glass, 95% efficient furnace, water sense toilets, fixtures and showerheads, LED lighting and CFLs, energy star rated appliances, walls insulated to R24 and ceiling to R50, hardwood floors made in WI direct from the mill and a fireplace mantel from recovered timber. Something old, something new, making the best use of the “embodied” CO2 and converting the home to high efficiency to reduce the “operational” CO2 gave a family a place they can call home.
To learn more about this residential renovation please check out the Oak Lane project.