The Built Environment

Energy Efficiency

Energy efficiency measures can indirectly impact the risk of carbon monoxide poisoning in the built environment.


Energy-efficient appliances are designed to operate more efficiently, producing less carbon monoxide during combustion.





Appliances are also tested for how much energy they use during typical use. Older, inefficient appliances may produce more carbon monoxide.

However, to reach net zero targets, we need to drastically reduce the amount of fossil-fuel-generated heating – in other words, gas or oil boilers – in our homes.

One way to do that is by installing a renewable heating technology, such as a heat pump or solar water heating.



Carbon monoxide is produced when fossil fuels burn without enough oxygen.

If we're not burning fossil fuels, then the risk of carbon monoxide poisoning is drastically reduced.


Some renewable heating sources still pose a risk of carbon monoxide exposure, for example, biomass boilers and stoves.




Biomass burning creates a range of gasses and particulate pollutants and has characteristics that differ from those produced by the combustion of other fuels.

In 2013, the Trust funded research carried out at Cranfield University, looking at the use of Biomass fuels in the UK and the potential human health and environmental impacts.

You can read more about this study here.


In 2021 the Trust funded a project to review the broader area of solid fuels.


The project was carried out by the Institute of Occupational Medicine (IOM) on the current state of play for the regulatory and policy landscape and incident data for carbon monoxide in domestic settings in the UK.


You can read more about this project here.


Improved Insulation

While the impact of energy efficiency measures may mean the risk of carbon monoxide exposure is reduced (because we're burning less fossil fuels), improved insulation measures have a consequence for indoor air quality.

As concerns about energy efficiency have grown, buildings have become ‘tighter’. Increased insulation, additional weatherstripping, high-tech windows and better construction techniques are designed to seal a house to prevent heat escape.

This has obvious benefits from an environmental perspective, as we use less fuel to heat or cool a home.




However, tighter building envelopes with better insulation can reduce the infiltration of outdoor air, potentially trapping carbon monoxide indoors. An airtight home can exacerbate indoor air quality problems. While it may be environmentally sound, the result can be a home with poor air quality.

Poor ventilation contributes to poor indoor air quality. Proper ventilation strategies must be in place to address this.


According to the US Environmental Protection Agency (EPA), certain indoor air pollutants can be as much as five times higher than outdoor levels.




UK Housing Stock

The other issue with focusing on improving insulation to improve energy efficiency is that it does not account for the older homes in which most people live.

The UK has the oldest housing stock in Europe. This is largely due to the legacy of dwellings built during the Industrial Revolution, which still form the backbone of our urban areas today.

In 2016, the Trust funded a study carried out at University College London. The study looked at the "Determinants of CO exposure in the English Housing Stock: Modelling current and possible future risks".

You can read more about this study here.





Most of these properties do not have good insulation.

Across England and Wales, 60% of houses have a wall insulation rating of “average” or above. This varies by region with 73% in the North East compared with 27% in London.

Homes with poorly insulated walls, windows, or attics will lose warmer air in the winter and cooler air in the summer, requiring excessive energy to keep an interior environment at the desired temperature.

In this article, Adrian McConnel talks about the challenges of Housing Policy and the Housing Trilemma.