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What Are Carbon Retrofits?
Carbon zero homes attempt to produce as much energy as they use annually. The achievement of this goal means that there are virtually zero carbon dioxide emissions associated with the house. Carbon neutrality is a popular sustainability housing strategy in the UK and other European countries. Newly built "carbon zero" homes combine solar panels, wind turbines, and other renewable energy technologies with energy-efficient appliances and airtight construction techniques such as those employed by passive houses.
Carbon retrofits adapt the theory behind carbon zero new home construction to existing homes. Carbon retrofit companies and products attempt to increase the renewable energy produced by a home drastically. Simultaneously, they aim to lower the energy demand by increasing the home's energy efficiency.
What Are the Benefits of Retrofits Over New Construction?
A study on housing in the UK found that a moderately sized new home built in Scotland accounts for more than 80 tons of carbon dioxide released into the atmosphere. Technological improvements certainly make newer homes more energy-efficient. However, the ecological cost of building new homes is often an overlooked part of the equation for accounting for the housing industry's environmental footprint.
Today, the commercial and residential building sector accounts for almost 40% of all carbon dioxide emissions in the United States each year. To reduce these emissions, the building community calls for newly constructed homes to be carbon neutral, and more importantly, for the renovation of older homes. Low carbon and carbon zero retrofits can keep an older home in use for more extended periods. They can also drastically reduce (or even erase) the carbon emissions associated with older homes that are often leaky and filled with energy-inefficient devices.
Housing experts often ignore the embodied energy of the raw materials used to build a new home. Still, it is one of the main contributors associated with the carbon footprint of homes. The adage "the greenest building is the one already standing" is generally true, so we like to focus on sustainable home renovation projects here at Rise.
What Are the Economic Benefits of Carbon Retrofits?
A newly built carbon zero home costs between 5 and 15% more than homes built to minimum code. However, the savings from reduced heating, cooling and electricity needs offset these costs. For example, the average household in the US uses around 900 kWh of electricity each month. This consumption amounts to about $110 per month (depending on your cost per kilowatt-hour). During the winter months, suppose an average of $600 is also spent on heating with propane, natural gas, or other fossil fuels. This energy use comes out to almost $2,000 per year on utilities. Carbon zero homes can almost entirely reduce that cost through passive house design, implementation of renewable energy technology, and other energy efficiency measures.
As an added benefit, investing in low carbon or zero carbon retrofit will most likely increase your home's value. Many homeowners can also apply for a home equity line of credit to finance a zero-carbon retrofit. They could see an immediate return on investment through the monthly savings on their electricity and gas bills.
What Do Carbon Retrofits Focus On?
While each carbon retrofit will be different for each home's specific context, most carbon retrofits focus on four main areas:
- Airtightness and insulation
- HVAC systems
- Appliances and lighting
- Renewable energy
Each of these areas of focus is expanded on below.
Airtight and Well Insulated
First, a carbon retrofit aims to make the home airtight by sealing windows, doors, and other drafty areas. This objective also increases the home's insulating properties in critical areas such as the attic while also investing in energy-efficient windows. This work can be a significant investment - in the range of $20,000 investment for an average-sized home. This estimate depends on how extensive the insulating work is, the type of insulation you choose, and the number of windows that need to be replaced.
Efficient HVAC Systems
Replacing the mechanical systems that heat, cool, and ventilate your home can go a long way to reduce your carbon footprint. This strategy often includes installing an electric heat pump system and a heat or energy recovery ventilator (HRV/ERV). These upgrades could cost you around $15,000.
Efficient Appliances and Lighting
Third, zero-carbon retrofits focus on improving the overall energy efficiency of your home. You might have to get rid of that old refrigerator and invest in a newer model and also switch out your lights for LEDs. Depending on the age of your appliances and other electric devices, you might spend another $5,000 on these upgrades.
Renewable Energy
Consider installing a solar system, residential wind turbine, or a hybrid renewable energy system to cover your home's energy needs. Fortunately, the other upgrades and renovations will reduce your home's energy demand, thus requiring a smaller renewable energy system. A five-kilowatt system will cost between $10,000 and $20,000 before tax incentives and rebates. There are various financing, leasing, and community solar options that you can consider to help you make renewables a reality.
In sum, a low carbon renovation can cost around $50,000. If you can meet all of your energy needs through the retrofit process, the $2,000 annual savings means that you should be able to break even within 25 years. That does not consider the immediate increase in value that you will perceive in your home's value or the increasing cost of energy. It also does not consider any rebates or incentives offered by local utilities and municipalities that may bring down that total spend, often by tens of thousands of dollars.
As the housing industry continues to move towards more ecologically sustainable homes, more of these financing options will become available to the average homeowner.
Tobias Roberts
Tobias runs an agroecology farm and a natural building collective in the mountains of El Salvador. He specializes in earthen construction methods and uses permaculture design methods to integrate structures into the sustainability of the landscape.
