Climate Change and Population Density

The best thing Montgomery County can do to reduce climate emissions is free of charge

Population density is intricately linked with carbon emissions. When Montgomery County enforces heavy restrictions on population density, it not only causes the cost of housing to skyrocket and economic growth to be crushed, it causes per capita carbon emissions to be considerably higher than neighboring Washington D.C. which boasts a much higher population density.

Source

Housing

Large houses use more energy than small houses. They use more energy to heat and cool as the systems have to pump more hot or cold air into a larger area while smaller houses don’t have as much square footage for their HVAC systems to cover. Detached houses lose hot and cold air through windows and walls causing HVAC systems to work harder to keep the house at a constant temperature. Attached houses such as townhomes are insulated by the houses next to them allowing the house to stay at constant preset temperature with less work than cooling and heating systems in a detached house. Shared walls keep hot or cold air trapped inside the unit rather than escaping outside.

When population density is high, people live in apartments and attached houses which are more energy efficient. Currently dense housing such as apartment and attached houses are illegal in the vast majority of land in Montgomery County. Regulations such as minimum lot sizes and multifamily housing bans cause extremely large homes to be built rather than smaller more energy efficient homes.

In East Bethesda an old small home was recently town down. In it’s place will go a $2.5+ million mansion that will likely be over 5000 sq ft. This home will take a large amount of energy to heat and cool. If it were legal to turn the home into a four-plex, the neighborhood’s average carbon footprint would be cut sharply. Montgomery County has rendered climate friendly housing solutions illegal via R-1 Zoning Regulations that prohibit multifamily homes on this lot.

In addition to certain physical structures being more climate friendly than others, land is a big source of carbon emissions. Since the plot in Bethesda will only remain as 1 house instead of 4, 3 additional houses will be built in outer-lying locations. It is likely that forests somewhere in the country will be cleared to make way for these new houses because they could not be built in Bethesda. When this forest clearing happens, carbon that was sequestered in trees and the ground will be released into the atmosphere.

If the County Council legalized small apartment buildings and attached housing county wide it would result in per capita residential carbon emissions dropping. Population density would increase allowing for a more energy efficient usage of land.

Transportation

Due to County land-use regulations on housing construction, population density is kept low. This causes everything to be far apart. In order to travel long distances we have to use energy to make the trip. The farther apart everything is, the more energy we have to use. This is why places with high population densities require much less per capita transport energy.

Since it is illegal to open small cafes, restaurants and grocery stores & gyms in residential neighborhoods, people must drive long distances in private vehicles to reach these amenities. The average American car is around 4100 lbs. It takes a tremendous amount of energy to move this heavy box of metal from point A to point B. When population density is kept low and residential and commercial uses strictly segregated, small shops can’t operate within walking and biking distance of enough business causing per capita transport energy to be high as people drive to the stores.

Another consequence of the County limiting population density is that public transit systems cannot run as efficiently. Busses and trains are a great way of reducing transport carbon emissions, but the more full they are, the better for the climate they are as the energy cost of running the bus is spread among dozens or hundreds of people. When the vast majority of the county is kept low density, busses often run mostly empty and there are less viable bus and train routes.

In the above example of the torn down house in Bethesda, the lot is within a 15 minute walk of the Bethesda Metro and multiple bus routes. Instead of 4 families filling up the train and buses, there will be only 1 causing transport energy to remain high. If multifamily homes were legalized on that plot, then per capita transport energy usage would decline.

Moving Forward

The best thing the County can do for the climate is free of charge. It requires scraping old land use rules that were put in place before we knew the devastation that climate change is having on the world. If zoning and land use regulations were eased, then the market would naturally build houses closer together causing emissions to drop. The County could then run more bus and train routes allowing more energy efficient forms of transportation. Less energy spent on housing and transportation means less carbon emissions and dependence on oil.