Derby Council have recently completed 4 carbon-negative homes in Arboretum, which generate more energy than they use. The overall result is achieved through energy efficiency measures and clever design. The result is a set of properties with an EPC rating of A and carbon-negative status. These effectively offset -0.5 tonnes of carbon dioxide every year.

As a result of this status, the homes will significantly reduce living costs for tenants. The energy efficiency measures installed include solar panels, insulation, and air source heat pumps. The homes are an excellent demonstration of how energy generation, retention, and recycling collaborate to form a unified approach to saving. Moreover, it represents a commitment from Derby Council to the provision of energy-efficient housing.

Quotes about the project

Chair of Derby Homes, Jsan Shepherd said:

• “We didn’t set out to build carbon-negative properties, we just wanted to create solid, well-insulated houses that use the latest energy efficiency technology.”
• “We’re investing in our existing stock too. We’re improving insulation in some of our coldest properties, installing solar panels on roofs and protecting the local swift population by attaching boxes to homes for them to nest safely.”
• “I’m incredibly proud to be part of these innovative, forward-thinking projects and I’m excited to see how this changes the landscape of social housing for the better.”

Councillor Shiraz Kahn, Cabinet Member for Housing, Property and Regulatory Services, said:

• “These properties not only provide homes for families who desperately need them, but the energy-efficient designs will mean the cost of heating and powering them should be more affordable.”
• “This site was prone to fly-tipping and was using significant Council resources to clear it regularly, so the project has also delivered much wider benefits.”

Councillor Carmel Swan, Cabinet Member for Climate Change, Transport and Sustainability, added:

• “To be building net zero council houses is a monumental achievement and one the people of Derby should be so proud of.”
• “The project is partnership working at its very best and feeds into the Council’s ‘Green City’ focus area.”

What does ‘carbon negative’ and ‘net zero’ mean?

Carbon negative, sometimes referred to as “climate positive,” goes a step further than net zero. Instead of merely balancing emissions with removals, a carbon-negative entity removes more carbon from the atmosphere than it emits. This means they are actively working to reduce the overall concentration of greenhouse gases in the atmosphere, not just neutralising their impact.

Achieving a carbon-negative status involves a significant commitment to reducing emissions. It also relies on then removing additional carbon dioxide from the atmosphere. This can be done through direct methods like enhanced land or ocean management to increase carbon sequestration. It can also be achieved through technological solutions like direct air capture and storage.

Net zero refers to achieving a balance between the amount of greenhouse gases emitted and the amount removed from the atmosphere. In other words, to be net zero, any carbon dioxide or other greenhouse gases that an entity emits must be counterbalanced by an equivalent amount being removed or offset. This can be achieved through a combination of reducing existing emissions and actively removing or offsetting the remaining emissions.

For instance, a company might reduce emissions by switching to renewable energy sources, improving energy efficiency. They can then offset the remaining emissions by investing in carbon offset projects such as reforestation or carbon capture technologies. The goal of net zero is to ensure that an entity’s activities don’t add to the overall amount of greenhouse gases in the atmosphere. This effectively neutralises its climate impact.

How do EWI, solar PV, and heat pumps contribute to a home becoming carbon-negative?

External Wall Insulation (EWI)

EWI involves adding a layer of insulation to the external walls of a building. This drastically improves the building’s thermal efficiency by reducing heat loss in the winter and heat gain in the summer.

By improving insulation, EWI lowers the energy demand for heating and cooling. This reduction in energy use directly translates to lower carbon emissions. This is especially the case in homes where the energy supply is not 100% renewable.

The improved energy efficiency brought by EWI is long-term. Once installed, it continues to reduce the energy demand of the home for many years.

Solar Photovoltaic (PV) Systems

Solar PV systems convert sunlight into electricity, providing a renewable source of energy that can power a home. By using solar energy, a home can reduce its reliance on grid electricity, which is often generated from fossil fuels.

Solar PV systems can significantly lower a home’s carbon footprint by replacing the carbon-intensive electricity from the grid with clean, renewable energy.

In many cases, solar PV systems can generate more electricity than the home uses. This excess can be fed back into the grid. Consequently, overall carbon emissions are reduced by providing renewable energy to others.

Heat Pumps

Heat pumps are highly efficient systems for heating and cooling a home. They work by transferring heat from outside the home into it and vice versa. Overall, they use less energy than traditional heating and cooling systems.

By replacing conventional heating systems that run on fossil fuels like natural gas, oil, or coal, heat pumps can significantly reduce a home’s carbon emissions.

When combined with a renewable energy source like solar PV, heat pumps can operate in an almost entirely carbon-neutral manner. If the electricity used to power the heat pump is generated from a renewable source, the system can contribute to making a home carbon-negative.