In this article epc4less, a Belfast-based Energy Performance Certificates (EPC) provider, advises homeowners how to enhance their home’s energy efficiency by insulating their property’s external walls.

What Is a Cavity Wall?

Until the 1920s, Belfast houses had solid stone or brick walls. However, towards the end of the 1920s, the concept of cavity wall gained popularity. The concept of cavity walls involves the creation of an air-filled cavity between the inner wall called the masonry wall, or inner block leaf, and the outer wall called the face brick or outer brick leaf.

Cavity Insulation Process Between 1930 and 1980

Until the 1980s, Belfast’s Building Control Standards did not require mandatory insulation of the cavity, which essentially meant that the cavity between the inner and the outer wall stayed empty. Therefore, for properties with no cavity insulation, the process of insulation involves drilling small coin-sized holes around the outer wall of the house and injecting a mix of a water-based adhesive and polyester beads into the cavity wall through. The polyester beads move around in the cavity, making sure that every inch of the cavity gets covered. Once the beads completely covered the cavity, the holes are covered with either cement or any material that goes well with the exterior wall of the building.

Cavity Insulation Process After 1980
In 1980s building regulations in Belfast changed making cavity insulation a mandatory requirement for all houses as built. Thus, after the 1980s, the process of cavity insulation included the use of polyurethane foam or Kingspan foam blocks, mineral fiber wool, and polystyrene granules. While all of these different materials were equally popular in different parts of Northern Ireland, in Belfast, mineral fiber wool and rigid Kingspan Insulation boards, were most common.

How Does Cavity Insulation Affect a Home’s Energy Performance Rating?

Most homeowners do not know that external walls are responsible for losing up to 33% of a home’s total heat energy. Thus, when homeowners and developers insulate the cavity they can increase their home’s Energy Performance certificate rating by anything between 5 to 10 points. The exact number varies depending on the size of the house — the bigger the house, the higher will be the heat loss from external walls. Thus, when homeowners with bigger homes insulate their cavity, they see a more significant improvement in their Energy Performance Certificate rating as compared to owners with smaller homes.

Mid-terrace properties have other homes attached on both sides. These properties, therefore, have a smaller heat loss perimeter. When owners of min terrace, end terrace or semi detached properties do cavity insulation, though they see an impact on their Energy Performance Rating, this impact is not as significant as that seen in large detached properties. Detached homes, or large semis, have a very long heat loss perimeter and therefore, benefit significantly from cavity insulation in terms of their energy performance.

To seek the advice of a Belfast-based domestic energy assessor you can search your local directory for “EPC Belfast