The importance of properly constructed cavities

The introduction of the Domestic Minimum Energy Efficiency Standard (MEES) in 2018 means all new homes must adhere to a minimum-level of energy efficiency. A positive move from the UK government, over the last couple of years it has led to a substantial cut in carbon emissions from home energy use and significantly slashed homeowners’ electricity bills.

Currently the housebuilding, and wider construction sector is one of the biggest polluters, responsible for around 40% of the global carbon footprint. The majority of this can be attributed to operational emissions; in other words, the energy needed to heat, cool and light a building. As such, initiatives such as the MEES are imperative in the fight against climate change.

Furthermore, they are essential if we are going to come anywhere near meeting our 2050 net-zero carbon targets, so it’s important that housebuilders get to grips with and adhere to this standard to meet its criteria.

Hazards of poor insulation installation

One of the most popular, simple and effective methods to help housebuilders meet the MEES is the installation of efficient cavity wall insulation, keeping warm air trapped within a house and reducing the need for excessive heating. The layer of insulation will keep the U-value of the wall low, lowering the transmission rate of heat energy and the risk of thermal bridging.

Unfortunately, poorly installed insulation can allow water from the outside in and be contaminated by mortar, increasing moisture levels inside. This issue is compounded as warm air traps moisture, leading to the formation of damp which can result in mould and mildew on walls, windows and the loft space. That’s just what you can see. Beyond the building itself, mould can negatively affect occupant health, which the housebuilder could be liable for.

In areas with adverse weather conditions, the moisture problem is further exacerbated as wind driven rain can easily penetrate the outer wall, leading to more water trapped within the cavity.

Prolonged exposure to damp can cause ailments such as asthma and other respiratory illnesses. This is why it’s crucial for housebuilders to make sure they install an effective cavity barrier and not cut corners. This will keep moisture to a minimum and help achieve the low U-values required by the MEES.

The solution

New innovations in building materials mean that backing blocks can be replaced by a non-porous, polypropylene sheet that maintains an effective air gap. This seals the wall against wind-driven rain and outside moisture, keeping the insulation within dry and preventing damp and mould. The sheet itself allows a thicker layer of insulation to be used in the cavity, delivering a lower U-value and improved energy efficiency.

In addition, using these sheets removes a layer of concrete within the wall further helping to cut emissions. Concrete is one of the most carbon intensive materials in the construction sector. As such, designing it out is vital to help keep the industry’s carbon footprint as low as possible.

In today’s eco-aware society, it’s crucial we push for more sustainable construction practices. Reducing operational emissions of buildings through a focus on energy efficiency is an excellent approach to this issue, and can also increase property values by up to 14%. However, it’s equally important housebuilders do not rush insulation installation or it could have a significant impact on occupants’ health.

Fortunately, choosing between energy efficiency and occupant health needn’t be a zero-sum game. We implore everyone in the industry to take the time to research what products are available that will achieve both strong U-values and protect residents from damp.

Charlie Ayers, founder, SureCav