Tear downs of old homes and building McMansions raises carbon emissions, and should be halted
The rising value of land and houses in Arlington has resulted in a very unhealthy rise in carbon emissions and other environmental damage because of the demolition of older and smaller houses and the building of mansions with often two or three times the living area of the demolished house. All living vegetation and trees are demolished on site to build the new house, and more open surface area is paved which thus increases storm water runoff and raises the temperature because of loss of tree canopy.
The County Board decided in 2019 to have a carbon neutral county by 2050. The demolition and then the construction of a new house typically raises carbon emissions by about 50 metric tons. A remodeling of an existing house typically raises carbon emissions by 15 m tons. A typical house in the U.S. generates 7.5 m. tons of carbon a year; even if the new house generated 30 percent less than the demolished house, it would take 20 years to recoup the carbon used in the new construction. However, new and larger square footage houses use more carbon in operating energy than the demolish house.
Energy use of a house is proportional to the square footage of the house. Thus a typical new 4,000 square foot house in Arlington would use nearly twice as much energy as an existing 1,400 square foot house. If the new house meets high insulation and building tightness standards (perhaps 30 percent more efficient), then the new house uses only 100 percent more energy.
The only realistic way for the Arlington County Board to halt this tear down disaster is to impose a county wide zoning called a historic district designation on all Arlington neighborhoods. A historic district zoning de facto blocks tear downs of houses, but does allow for renovations and additions.
The historic district also requires that older trees and existing green space be preserved so that there is no loss of tree canopy. There is one Arlington neighborhood Maywood that has had a historic district since the late 1970s and in the 40 years, no house has been demolished although most have been renovated and expanded.