Do Exterior Blinds Actually Work?

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Do exterior blinds actually work? And are they better than air conditioning? In this post, we explain the differences and explore how effective this sustainable alternative really is.

To answer the question:

Yes, studies show that exterior blinds can be extremely effective at blocking the sun’s heat and keeping your home cool in summer.


Outdoor blinds offer a sleek, contemporary finish to all kinds of properties that can add value as soon as they are installed. However, they not only look stylish but provide a neat, sustainable solution to overheating challenges, particularly in large homes with large windows. 

How Do External Blinds Work?

Exterior blinds are fitted on the outside of a window, rooflight or glazed door. They consist of an aluminium headbox (which stores the fabric when the blind is raised) and aluminium side channels, which help keep the fabric taut while the blind is down.

In hot weather, windows act like radiators in a room. The larger the window, the more heat comes through, creating an uncomfortably warm house. The standard solution is air conditioning, which pumps cold air into a room and helps to keep the temperature at a comfortable level.

In contrast, external blinds work by reflecting the heat away from the window before it has the chance to enter the house. Opting for a basketweave screen fabric still allows you to see through the window, but prevents up to 80% of the heat from the sun entering the house.

Cooling Backed by Research

Research on the effectiveness of external blinds is limited at the moment, but a study undertaken by the Pacific Northwest National Laboratory* showed that exterior blinds fitted to west and south-facing windows resulted in a reduction in cooling requirements of approximately 20%. The researchers found that the higher the outdoor solar irradiance (ie the more sunlight there was), the greater the energy savings were.

In addition, the installation of the external blinds made the indoor environment more comfortable, with temperatures averaging 9°F (5°C) less than a control site with no external blinds. The external blinds also reduced indoor temperatures by around 2°F-3°F (1°C-2°C) more than interior vinyl blinds. 

(Temperature assumes a sunny day where average midday daytime temperatures were around 75°F (24°C).

As part of the study the researchers at PNNL also surveyed homeowners who had exterior blinds installed, to understand how they used the blinds and their overall perspective.

'The homeowners of all three field sites reported satisfaction with their application of the exterior shades. The homeowners were particularly satisfied with the exterior shade’s ability to reduce glare while preserving a view to the outdoors.

The homeowners also found the exterior shades to be reliable, easy to use, and provide improved comfort in the indoor space. Improved occupant comfort, in terms of reducing the indoor temperature, was confirmed with field measurements at all three occupied field sites.' 

- Evaluation of Exterior Shades at PNNL Lab Homes and Occupied Field Sites, October 2020


A Seven Degree Reduction

Just how effective external blinds are at reducing indoor temperatures is demonstrated by one of our projects, for luxury penthouses built overlooking Gloucester County Cricket Ground in Bristol. We were contacted by the owners to provide a solution to their overheating problem; with a fifth floor position and large windows, the apartments had stunning views of the pitch, but indoor temperatures were climbing to 29°C on an average day, creating unbearable living conditions for the owners.

The most effective solution proved to be installing Renson Fixscreen exterior blinds. The open weave of the screen fabric preserved the views of the pitch, and produced dramatic results: the average indoor temperature dropped from 29°C  to 22°C almost immediately.


Are Exterior Blinds Better than Air Conditioning?

If you prefer to have your home precisely climate-controlled, external blinds can't do that; air-conditioning is probably the best solution for you. However, if you prefer a sustainable, long-term solution to keep your home cool and comfortable without harming the planet, then external blinds offer an excellent alternative. 

Not requiring huge amounts of energy to run or using planet-harming refrigerants, external blinds are unobtrusive and easy to maintain. You can even connect them to a home automation system, and control remotely from your phone, or set them to raise or lower at certain times of day to maximise their cooling effect.

In conclusion, studies and anecdotal evidence demonstrates that external blinds are a very effective solution for keeping your home cool and comfortable. We work with Renson, a leading European supplier of high-quality external blinds ideal for luxury properties. Browse our range or contact us today to find out more. 

*Evaluation of Exterior Shades at PNNL Lab Homes and Occupied Field Sites Final Report: October 2020, by WE Hunt and KA Cort