Summer: long days, BBQs, ice creams, and unfortunately, for many of us, uncomfortably hot houses. When the mercury starts to rise, it can turn our comfortable homes into stifling hot boxes, making it difficult to sleep, work, or relax. But what if we told you there’s a solution? EWI can do wonders for your home’s temperature regulation, not just in winter, but crucially, during the heat of summer too.

What is External Wall Insulation?

External wall insulation involves applying an insulating layer to the exterior of a building. This technique improves the energy efficiency of your home and provides a refreshed aesthetic appeal. What many people don’t realise, however, is that in addition to keeping your house warm during the colder months, it can also help keep your home cooler in the summer. We promote three major systems of insulation: Mineral Wool, EPS, and Phenolic Foam.

Mineral wool, also known as rock or stone wool, is made from molten rock that is spun into fibres and then formed into panels or batts.

• Fire Resistance: Mineral wool is non-combustible and has excellent fire resistance.
• Acoustic Properties: It is effective at reducing noise transmission thanks to its dense fibrous structure.
• Environmental Impact: Mineral wool is made from abundant, naturally occurring materials and is recyclable.
• Breathability: It is vapour permeable, allowing moisture to escape from the building and thereby reducing risks of dampness and mould.
• Durability: Mineral wool is robust and maintains its performance over time.

Expanded Polystyrene is a lightweight, rigid foam insulation material.

• Thermal Performance: EPS has good thermal performance.
• Weight: It is lightweight, making it easy to handle and install.
• Moisture Resistance: EPS is resistant to water absorption, which helps to maintain its insulating performance.
• Cost: It’s generally a less expensive option compared to other insulation materials.
• Environmental Impact: While it is not as environmentally friendly as some other options due to its petrochemical origins and difficulties with recycling, its longevity and insulation properties can still make it a viable option.

Phenolic foam is a type of rigid foam insulation that is known for its excellent thermal performance.

• Thermal Performance: Phenolic foam has one of the lowest thermal conductivities of any insulation material.
• Fire Performance: It has good fire performance characteristics and low smoke emission.
• Moisture Resistance: Phenolic foam performs well in damp conditions and is resistant to water absorption.
• Thickness: Because of its high insulating performance, phenolic foam can be thinner than other materials for the same level of insulation, which can be useful where space is limited.
• Cost: It’s generally a more expensive option compared to other insulation materials.

How does EWI help keep my home cool in the summer?

The effectiveness of EWI in cooling your home in summer hinges on a property known as the ‘thermal lag.’ This is the delay between the peak external temperature and the point at which the internal space reaches peak temperature. With good insulation, the thermal lag is extended. This means that by the time the peak internal temperature is reached, the hottest part of the day has often passed.

In essence, EWI creates a thermal barrier. In hot weather, heat will always try to move to a cooler place following the natural flow of hot to cold. External wall insulation acts as a buffer and absorbs this heat, slowing its transfer into the home.

The denser and thicker the insulation material, the more heat it can absorb and the slower that heat will be transferred. So during a hot day, the heat from the sun hits the exterior of your house. Instead of the walls absorbing the heat and transferring it inside, the insulation layer (which is covered by a protective render) absorbs this heat.

Moreover, due to the thermal lag, by the time some of the absorbed heat might start to seep into your home, the outside temperature has often already begun to drop. This means your home stays cooler during the day, and any heat that does eventually make it through the insulation does so in the cooler evening when it’s less of a problem.

Choosing the right render for your EWI system

When applying an external wall insulation system, one of the crucial components is the render. This is the outermost layer, and it not only protects the insulation material but also contributes to the overall thermal performance and aesthetic appeal of your home. There are several options available, including silicone, monocouche, and lime render, each with unique properties that can enhance the insulating capabilities of the system.

Silicone render, for example, is highly weather-resistant and flexible. It allows the walls to breathe, helping maintain a comfortable indoor environment throughout the year. Monocouche render is another excellent choice. It’s durable, resistant to abrasion, and does not require painting, reducing maintenance efforts. Lime render, a traditional option, is ideal for older, solid-wall properties due to its high breathability and flexibility.

The environmental and economic perks

Aside from the comfort aspect, external wall insulation is a great way to reduce your environmental impact. By keeping your home cooler in the summer and warmer in the winter, you’re reducing the need for artificial heating and cooling. This leads to lower energy consumption, reduced carbon emissions, and substantial savings on your energy bills.

In conclusion, if you’re looking to keep cool this summer, external wall insulation could be a fantastic solution. Not only does it make your home more comfortable and energy-efficient, but it also helps you save on utility bills and contribute to a healthier planet. So when you’re considering upgrades to your home, remember: a well-insulated home isn’t just for winter. It’s a year-round comfort solution that might just be the key to your most enjoyable summer yet.