Green air conditioning: How houseplants can cool your home for free

May 01, 2024
Potted plants in an apartment.
Houseplant expert explains NASA-approved method of cooling your home naturally, and the seven best plants to grow ahead of this summer’s heat waves.

Demand for at-home air conditioning has skyrocketed over recent summers. In London, demand has increased by 5% every year since 1980. But with the cost of installing just one air conditioning unit up to £3,000, it’s not an accessible solution for many.

But houseplants could be the answer. Craig Morley, gardening expert at Budget Seeds, explains how to harness the power of plants to cool your home for free this summer: 

How transpiration works 

“Many people are aware that houseplants can improve the air quality of your home by circulating the air and removing pollutants. But not enough people are aware of the air-cooling qualities of plants. 

“Transpiration is the process by which water flows upwards through a plant, from the soil to the leaves and stem. As well as delivering water and nutrients to the plant’s cells, this process keeps plants cool as water evaporates from the leaves. 

“Transpiration also cools the area around the plant. NASA’s Earth Science Division proved this means plants can help combat rising temperatures caused by climate change. On a smaller scale, having houseplants in your home can help cool your home in summer - free, eco-friendly air conditioning, if you like.”

Six tips to promote transpiration in your plants

1. Keep your houseplants well-watered 

“If a plant is not watered often, this can reduce the rate of transpiration as the plant tries to conserve water. Giving your houseplants ample water will encourage transpiration and help to cool your home during hot weather.”

2. Increase the humidity 

“Placing your plant wet pebble tray can also promote transpiration. As the water evaporates from the tray, it creates a bubble of humidity surrounding the plant. Investing in a humidifier also has the same effect.” 

3. Group plants together

“Grouping plants together also helps to create a humid microclimate. This prevents each plant from drying out, which hinders transpiration.”

4. Upsize your pot

“Plants in containers may transpire less, as their roots are often confined within a small space, and this can make them prone to water stress. Of course, houseplants are usually kept in pots but opting for a larger pot can mitigate this issue.” 

5. Avoid pruning in the summer

“Pruning can also decrease transpiration in a plant, as it reduces water uptake. Avoid pruning during warm weather to ensure transpiration is not hampered.”

6. Satisfy your plant’s needs

“Houseplants placed in an environment that does not satisfy their needs will not be as efficient at cooling your home. Consult your plant’s care tag or use the internet to research ideal growing conditions. How much sunlight does it need? Does it prefer dry or humid conditions?” 

Seven of the best air conditioning plants

“Plant species have different leaf structures which affect their rate of transpiration. A larger leaf size means more ‘pores’ through which to release excess water which means increased transpiration. 

“Similarly, species with leaves that are curved or folded may not lose as much water as their shape helps to conserve water. As leaves age and prepare to shed, transpiration usually reduces too. 

“It’s also believed that a plant’s rate of transpiration improves with age. This is likely due to the increased surface area plants benefit from as they grow.”

1. Snake plant (Dracaena Trifasciata)
2. Peace lily (Spathiphyllum Wallisii)
3. Aloe vera (Aloe Barbadensis Miller)
4. Bamboo palm (Chamaedorea Seifrizii)
5. Boston fern (Nephrolepis Exaltata)
6. Golden postos (Epipremnum Aureum)
7. Spider plant (Chlorophytum Comosum)

"Some plants transpire more than others so if you’re investing in new plants, it’s important to know which ones to choose for their air-cooling properties. Snake plants, peace lilies, aloe vera, bamboo palm and Boston ferns are all great options as they have high rates of transpiration.

“For anybody new to plant parenting, good low-maintenance choices include golden pothos, which are also valued for their air-purifying qualities, and spider plants, which are perfect for bathrooms because they enjoy moisture." 

Our new homes in London are built with enhanced double-glazing and highly-efficient insulation as standard. As well as keeping your home warm in winter, our energy-efficient apartments are designed to prevent overheating when it’s hot.