Tackling Overheating in New Build Homes

With the Government looking to build 1.5 million homes this parliament, housebuilders need to consider the issue of overheating.

Steve Pearce, Product Manager at Vent-Axia, discusses overheating challenges in new build homes and how the newest ventilation solutions can help tackle them.

As part of the Planning and Infrastructure Bill, the Government plans to get Britain building faster. The aim is to accelerate the Government’s Plan for Change to build 1.5 million homes this Parliament. With such an ambitious programme, it is vital that housebuilders carefully consider the growing issue of overheating in new-build homes.

In the UK, homes have not traditionally struggled with overheating. However, today’s new build homes are very different. High levels of air tightness and insulation, extensive glazing, and limited solar shading all contribute to an increased risk of overheating. At the same time, the number of openable windows is often restricted due to noise, air pollution, or security considerations, adding to the overheating problem.

Climate change and increasing summer temperatures add another layer of complexity. Urbanisation has also contributed to raised temperatures, especially in city centres, like London, where the Urban Heat Island effect can elevate nighttime temperatures by 10ºC compared to its surrounding rural areas. Consequently, some new homes are experiencing indoor temperatures above comfort levels, and in some cases, the temperatures are posing health risks.

Part O

The UK Government recognised the seriousness of the overheating problem, introducing Approved Document O of the Building Regulations in 2021. Part O addresses overheating in new dwellings, care homes, and student accommodation. Its core objective is to protect occupant health and wellbeing rather than being aimed at thermal comfort. It has two overarching requirements: limiting unwanted solar gains and ensuring excess heat can be removed from the home.

When it comes to limiting solar gains and removing excess heat, Part O prioritises passive measures first. Part O offers two calculation methods to meet requirements: the Simplified Method, which is suitable for sites that are not affected by noise or air pollution; and the Dynamic Thermal Modelling (CIBSE TM59), where simplified compliance is not possible.

Ventilation is a crucial part of the solution for overheating. Part O lists acceptable methods in order of preference, starting with opening windows, followed by ventilation louvres, mechanical ventilation, and lastly mechanical cooling. A range of ventilation is available to help housebuilders mitigate overheating risk in different building designs and locations.

Ventilation

Housebuilders can adopt various ventilation strategies to help reduce overheating. When it is not possible to use windows for ventilation, modern extract systems can help remove excess heat. For example, Vent-Axia’s NBR CoolBox Kits offer on-demand heat extraction, are compact, low noise and suitable for installation in all habitable rooms.

One of the latest innovations available is a combined MVHR unit with a hot water air source heat pump. This type of system combines two technologies, offering 2-in-1 – renewable hot water and a free cooling solution. For example. The Lo-Carbon Sentinel Econiq-Cool (KERS), Vent-Axia’s latest flagship MVHR system, features all-new controls allowing communication with the KERS Coolboost Heat Pump.

Meanwhile, the latest Mechanical Ventilation with Heat Recovery (MVHR) units, such as Vent-Axia’s Lo-Carbon Sentinel Econiq, deliver coolth or heat recovery efficiencies of up to 93%. The Lo-Carbon Sentinel Econiq comes with intelligent automatic 100% summer bypass capabilities, offering free cooling. But, if MVHR alone is insufficient in tackling overheating throughout the year, specifiers can have the benefits of the MVHR systems with integrated DX cooling modules, such as Vent-Axia’s Lo-Carbon Sentinel Econiq Cool-Flow. This option features intelligent controls that switch automatically between heat recovery, summer bypass and active cooling via the DX cooling module.

With overheating becoming an increasing problem in new build homes, it is important to consider the low carbon ventilation solutions that are available to tackle it. Overheating is a serious health issue, but it is also a comfort issue, which is why ventilation is key to solving the overheating challenge and helps futureproof homes against the climate changes ahead.

Vent-Axia has recently launched its latest CIBSE-approved Continuing Professional Development (CPD) course: ‘Overheating in Residential Properties: Part O – How ventilation can be part of the solution to remove excess heat’. This informative and timely course provides a greater understanding of overheating, legislation and guidance, and appropriate ventilation solutions to combat overheating.

To find out more about this and other CIBSE-accredited CPD courses from Vent-Axia visit the CIBSE website. To book Vent-Axia’s CIBSE-approved CPDs with one of its experienced ventilation experts, email cpd@vent-axia.com. For further information on products and services offered by Vent-Axia call +44 (0) 344 856 0590 or visit https://www.vent-axia.com/.