How to cool your workplace

Image from "Shade the UK"

What are the most effective "passive cooling" measures for buildings? (Passive measures stop buildings from getting hot in the first place, where active measures cool the buildings down once they are already too hot).

The answer varies depending on the age and type of building. Older buildings built before 2000, while sometimes having better ventilation than more contemporary buildings, tend to overheat due to large amounts of poor quality and fully transmissive glazing. Newer buildings may already have overheating measures in effect, and so a bespoke overheating assessment is probably the first step.

Research commissioned by the Climate Change Committee found that several interventions, considered low cost, consistently performed well in buildings constructed before 2000:

• Internal solar blinds with a solar reflectance greater than 0.35, kept closed during the hottest parts of the day. This is one of the most effective measures, reducing the time spent in the year over the maximum comfort temperature by around 80% (defined in CIBSE TM59, it varies based on the average outside temperature).

• Low g-value solar-control film applied to the outside of windows, reducing the amount of the sun's heat that enters the building (g-value is a proportion of transmission of radiation through the window 0-1).

• Ceiling fans - these help occupants stay cool during the hotter parts of the day with increased airflow over the skin but mainly increase ventilation during cooler parts of the day, helping the building to cool down at night. These were surprisingly one of the most effective solutions and very affordable, with low energy demand.

There are also some external solutions that are highly effective. The cost of them might be an order of magnitude higher, mainly due to the requirement of external scaffolding, but these should be considered when a larger building can benefit from the cost saving at scale, or for low rise buildings.

• External shutters, which were the single best-performing measure tested. In some cases they reduced the number of hours above 28°C by almost 90%, because they block solar heat before it enters the building.

• Replacement glazing, using modern low-g-value solar-control glass to reduce the amount of heat transmitted through windows.

• Fixed or temporary external shading, such as canopies, brise-soleil or awnings above windows. This was the second most effective intervention overall, but often comes with higher installation costs.

• Other studies point out the benefits of natural planting around the exterior of buildings. Trees can provide shading for the external windows, and provide passive cooling to the local external air as well.

As well as these measures, some of the most effective solutions are behavioural. For instance, if the air is hotter outside than inside, windows and blinds should be kept shut, unintuitively. For a more comprehensive list of measures that might be suitable to your home or workplace, check out the overheating adaptation guides at bit.ly/shade-uk.

Some solutions that are often proposed may not be the first port of call in adapting old buildings, such as painting the roof white (high cost, limited effect).

In the consecutive heat waves we have experienced this summer, many of our homes and workplaces have been unbearably hot. According to recent overheating studies, hospitals, care settings, and schools are among the building types most at risk. NHS buildings regularly exceed recommended temperatures in summer, putting patients and workers at risk, while overheating in classrooms affects learning and concentration. Many of these buildings were designed for a cooler climate than the one they now operate in and are increasingly struggling to cope with extreme heat.

The predominant active cooling measure is air conditioning. While many are aware of active measures, a recent study found that nearly 10% of UK energy use currently goes to air conditioning during the summer, and this is set to grow rapidly as the summers get hotter.

Ecologically minded socialists should be demanding passive solutions in their workplaces as well. Air conditioning will still have a role to play, particularly in places where overheating could be life-threatening such as intensive care units, but relying entirely on air conditioning would mean higher energy use and higher emissions. Wherever possible, passive measures should come first, and a combination will become increasingly necessary as the climate continues to heat up.

Studies show that buildings overheat for two main reasons. First, sunlight enters through glazing and becomes trapped as heat inside the building. Second, poor ventilation prevents that heat build during the day from escaping when the temperatures cool at night.

Passive cooling measures vary enormously in both cost and effectiveness, but the common theme is simple - the most effective interventions stop sunlight reaching the inside of the building. Once solar radiation has entered through the glass and heated internal surfaces, removing that heat becomes far more difficult. Researchers have identified which measures deliver the biggest reductions in overheating for the lowest cost. Being educated on this means we do not have to accept employers' or landlords claims that nothing can be done. We can demand improvements and show which measures provide the greatest benefit for the money spent.

During Covid, many unionists challenged their employers over unsafe working conditions, calling on section 44 of the Employment Rights Act 1996, which protects workers who reasonably believe that they face a serious and imminent danger. This can be used as a tool, where unsafe working conditions can be confronted through impromptu walk-outs, and was used successfully by many, including workers from my own branch who collectively refused to come into the office in 2020, leading to flexible working arrangements.

We are now seeing similar campaigns emerging because of overheating. Bus drivers organising in Unite have been refusing to work during heatwaves and now many have balloted to strike, calling for proper cooling systems, regular breaks, access to water and a maximum safe working temperature.

That might be the best solution for a bus. Most of us work in buildings and passive measures should be fought for here as well. Demands might include:

• An overheating action plan - a strategy for keeping the building cool through behavioural changes, with training and compensation provided for workers who operate the building, especially for janitorial or security staff who might be asked to open windows and purge heat during the evening or early morning. This should also have provision for drinking water, cool rooms, and a maximum working temperature.

• Passive cooling measures for the workplace, to be developed based on the specific building, but at least making use of low g-value window film, thermal blinds, and provision of freestanding or ceiling fans for all staff as a temporary response to deal with the immediate heat.

• Ultimately for full upgrades of our workplaces, making use of all possible passive measures, as well as the installation of air-conditioning or other active measures, to be used primarily just during the hottest days or for the most vulnerable users.

Walking out of an overheated workplace does not mean workers escape the heat, but it can be a powerful way of forcing employers to act. We should have safe places to work, to live in and to travel; a comprehensive solution is required to adapt to climate change, and this is likely to require a wider reorganisation of society.