Guidance

Existing home ventilation guide

Updated 15 December 2021

Applies to England

Section 1: Introduction

This guide is intended to help you better understand the ventilation of your home. This guide does not replace the manufacturer’s instructions for ventilation systems, which should always be followed.

Section 2: What is ventilation for?

Ventilation is the exchange of fresh air from the outside and stale air and moisture from the inside of a property. Poor ventilation can result in harmful pollutants and moisture being trapped in the property which, in turn, can damage the health of people and the house itself.

Reducing condensation and mould growth

Through household activities such as showering, washing dishes and clothes, cooking and even just by breathing, we generate a lot of moisture that enters the air inside our homes. Without effective ventilation, this moisture can be trapped in the home and turn into condensation, particularly in the winter when surfaces such as walls are cold. The condensation can lead to damp and mould growth which can cause damage to your home and lead to respiratory illnesses for you and your family.

Protecting health

Without good ventilation, there will be more substances in the air that can cause harm to you and your family. This includes pollutants from cooking, cleaning products, hygiene products and fabric furnishings.

Section 3: What do the Building Regulations require?

Building Regulations require that the ventilation in your home is not made worse by installing energy efficiency measures. When work is done to homes gaps and cracks are often sealed up. These gaps and cracks were providing ventilation and in older homes may have been the only source of ventilation.

When windows are replaced, a background ventilator or ‘trickle vent’ should be placed in the new window. This will replace any ventilation you lost, when installing a new window, because your previous window was leaky. If replacing your window did not reduce the amount of useful ventilation, this should be proven, and more ventilation is not needed.

Section 4: How to use your ventilation?

In order to ensure the ventilation in your building works as well as possible, you should:

• Always leave trickle vents open and unblocked, even in winter. You will use a little more energy to heat your home, but have fresh air to prevent illnesses.
• Where possible, leave doors between rooms open to ensure cross-ventilation. This will further improve the amount of fresh air drawn into the building.
• Regularly clean any extractor fans in bathrooms and kitchens.
• Check the manufacturer’s instructions for any whole house mechanical ventilation system you have and ensure the filters are replaced in line with those instructions, usually this would be annually.