The Paradox of Choice

Lessons we could learn in the window and door industry

Whilst lounging by the pool on holiday last month I thought I would take the opportunity to read something other than the usual trashy novel. I asked friends for some advice and I was recommended “The Paradox of Choice” by economist Barry Schwartz. Just before you all stop reading this blog, it isn’t a book review of some obscure economist, so bear with me and you will see where I am going here.

The central theme of the book is that too much choice leads to paralysis and ultimately less satisfaction with the choices we have made. When presented with literally hundreds of options we get more concerned about the alternatives we could choose and worry that we will make the wrong decision. And when (and if) we do finally choose one, we can’t help but think was it the right choice? Which actually leads to less satisfaction with the purchase in the end. The book does expand on this very paraphrased idea and is well worth a read (or watch his very interesting and concise lecture.)

In the book Schwartz uses the example of his local grocery store with 189 options on salad dressing, with even more “make your own” options with 10 types of olive oil and 15 brands of balsamic vinegar. In our world of windows and doors the options available are the grocery store example multiplied and then multiplied again. Take the composite door market for example: once you have chosen foam filled over timber core (and now hybrids!) you are confronted with hundreds of colours (one major company was marketing 15 shades of grey – as if this was a benefit); hundreds of glass options; not just lock systems but choices of cylinders; sidelights or no sidelights; brass or chrome furniture in multiple designs – the list goes on … and on … and on. When Door Stop came to the market they claimed that six billion combinations were available!

When confronted with this amount of choice and – in many cases – conflicting information from online reviews, how can the consumer make a choice? I know this only too well from personal experience as, for seven years now, my wife has been asking me (actually telling me!) to get a new front door. In her view its simple: something that looks better than the old timber door we have, preferably in grey (but its not a deal breaker) and more secure than the 25 year old Yale lock that we have currently. For me though paralysis has set in – I have just too many choices; Which grey? Should we have biometric or standard lock? Which door? Which frame – and should it match? And I haven’t even started on the glass options. On numerous occasions I’ve almost got to a final decision, but at the last minute I think to myself:-

“is that the right choice … what if I get it wrong? … after all, this is supposedly my area of expertise”

I am not decrying the choice available today in the market; there are some incredibly innovative products out there and I fully understand that each company wants to differentiate its offering from the next guy. As a supplier to the industry we have been offering more and more choices to our customers for years … in fact it’s the cornerstone of our business model. But the more and more I think about the issue and see it from the consumer or installer and retailer’s point of view, the more I believe that the ever-expanding choices are making decisions more difficult to make – and maybe even reducing the overall volumes sold.

I hear you say:

“it’s all very well to talk about too much choice but we have to offer what the consumer wants!”

and I agree. The discerning customer, who has done his or her research, or with the guidance of a technically competent sales person, should be able to get what they want and take advantage of the plethora of choice this wonderful industry has to offer. But for the consumer who just wants a door or windows to serve a function, whilst looking good (rather like my wife), how do we streamline the choice and make the decision simpler and in the end more rewarding?

Watch this space for information on the new RegaLead Essentials composite door range – a simple range of doors, colours, glass and furniture options, neatly packaged and marketed to help you sell to those people – like my wife – who just want a door.

Heat Build-Up in Painted PVC-U Profiles & Composite Doors by Bartosz Machyna

Technical Bulletin 104


The building products market has seen unprecedented growth in demand for coloured fenestration products in the last few years. Driven by manufacturer innovation and consumer demand, more than 70% of windows and doors in Continental Europe are now coloured and the UK is fast following their lead.

One in four UK windows and doors is now coloured, and a significant 35% of PVC-U products are now anthracite grey. Moving away from traditional white or woodgrain, the move towards contemporary design has also accelerated growth in darker coloured composite doors, which are now popular in dark shades of painted green, blue and black.

This ‘colour explosion’ may be a great sign of a vibrant industry, but as with every emerging market, there can be contra-indications. People may remember the problem of warping rosewood PVC panels several years ago – bad for the industry, but due to lower volumes, that problem was on a tiny scale compared with the hundreds of thousands of coloured doors we now have in the market.

The threat facing us that the industry cannot ignore has its roots in basic physics. Put simply, the darker the colour (anthracite greys, blacks, dark greens and blues) the higher the absorption of incident sunlight (Solar Heat Gain) which is converted into heat (Heat Build Up), while the titanium dioxide present in white, cream and lighter colours reflects more of the incoming energy and the infrared waves that do the damage. The higher the Heat Build Up, the higher the material expansion rate, which ultimately affects the product’s integrity and stability.

Expounding the problem is the complexity of different substrates with different expansion rates which are housed together – take doors, where for example a black GRP composite product could be assembled into a white PVC frame. The different rates of expansion under temperature changes can lead to serious product failure, even to the point where hardware slippages mean doors won’t lock or open. In parallel, additional complexities are arising from a migration towards new techniques and applications including mechanical joints and increased use of thermal reinforcements.

This report will not come as no surprise to industry which has seen the introduction of various attempts to the try to address the problem, especially by thermal reinforcements. But these solutions (which could potentially exacerbate the problem) are only remedial – they do not address the problem of heat build-up at source, before it happens.

In this Special Report, we look at the physics behind the threat, the impact on different substrates and thanks to testing, what next generation painting solutions are available.

The Power of Solar Radiation

We all know that feeling when you get into a hot car that has been sitting in direct sunlight, when the black seats and steering wheel are too hot to touch. But how many of us understand the science behind this?

Sunlight is not only comprised of Ultraviolet (accounting for 5% of the sun’s energy reaching earth’s surface) and the Visible light spectrum (50% which makes up the wavelengths that give us the perception of colour, but there is also the Infrared spectrum which is not visible to the human eye. Infrared radiation does not influence the tone of a colour but is absorbed by the object and converted into heat.

To appear black, a pigment must absorb practically the entire spectrum of visible light. During the absorption process, light energy is converted into heat energy, causing the temperature of the surface to rise. Two of the most extreme examples of this are carbon black and copper chromite. These materials not only absorb virtually all the visible light, but continue out onto the infrared region as well. In contrast, a white object reflects all wavelengths of light, so the light is not converted into heat and the temperature of the object does not increase noticeably.

solar radiation absorbtion

CAPTION: Roughly 50% of solar radiation is absorbed at the earth’s surface. Black surfaces usually absorb up to 90% of this energy and therefore get hot. White surfaces, on the other hand, absorb only up to 25% and tend to stay much cooler.

Total Solar Reflectance

Total Solar Reflectance (TSR) is the percentage of irradiated energy that is reflected by an object. The effectiveness of the reflectance can also be expressed in terms of Heat Build Up or HBU, as determined using ASTM* D-8403 test method, which shows the rise in temperature above the ambient. As a benchmark our tests show that a standard white UK window profile will have a reflectance of around 88% and Heat Build Up of between 20°c and 22°c .

The graph below shows the % of reflectance generated from a white frame.

*The scope of this test method covers the HBU in rigid and flexible PVC building products above ambient air temperature relative to black, which occurs due to absorption of the sun’s energy

reflectance graph

A black coated surface shows the complete opposite, only 5% of all variants of the spectrum are reflected (95% absorbed) and the HBU is 44°c above ambient temperature.

black coated surface reflectance graph

Expansion Rates of Different Substrates

With some substrates, like wood, temperatures of up to 700C (1580F) do not significantly influence the substrate. However, with PVC-U this is a different story, as high temperature can cause critical damage, such as softening, deforming and changes to the mechanical properties of the substrate.

Expansion Rates of Different Substrates

Heat Build Effects on PVC-U

PVC-U profile has an expansion rate 0.00006/oc which equates to 1.2mm per metre for every 20oC change in temperature. This may at first look insignificant, but the chart below shows the dimensional changes in typical two metre PVC-U window frame from a baseline temperature of 10 oc.

Ambient 10 20 30
White Profile 32 42 52
2.64mm 3.84mm 5.04mm
Black Profile 52 62 72
5.04mm 7.44mm 8.64mm

The above numbers are for non-reinforced PVC-U and the use of aluminium or steel reinforcement systems will have a positive effect on these findings.

Use of Cool Colour Infra-Red Reflective (IRR) Pigments

To counter the problem of heat expansion with dark colours, specialist building product paint manufacturer RegaLead has developed a range of Cool Colours to complement its existing range. These Cool Colours use specialised Infra-Red-Reflective (IRR) Pigments which substantially reduce any heat build-up. The IRR pigments reflect 44% of the infrared wavelength and the heat build-up is only marginally over that of standard white profile. The graph below shows the reflectance properties of Cool Colour Black across the spectrum of wavelengths.

reflectance properties of Cool Colour Black

In testing, the HBU of white PVC-U profile was 22.33oc. With the IRR black paint under the same conditions, the HBU was 24.91oc. In contrast, with standard black paint the HBU was 42.22oc – more than enough to warp a frame.

RegaLead can provide TSR (total solar response) and HBU (Heat Build Up) values for any Cool Colour formulation, but here’s a sample.

Standard Paint Versus Infra-Red- Reflective Paint

PVC FRAME COLOUR (Using white as the benchmark)
Standard Paint IRR
White not painted TSR 81.51
HBU 22.33
Black TSR 4.06 38.42
HBU 42.22 24.91
Anthracite TSR 6.53 42.36
HBU 41.63 24.91
Slate TSR 9.58 36.9
HBU 40.92 24.46
Steel TSR 7.78 30.86
HBU 40.26 26.78
Cream not painted TSR 76.18
HBU 22.65


  • The white sample frame had the highest TSR value, as expected
  • The cream samples all had high TSR values again as expected due to the high amount of white in the colour
  • The slate blue and anthracite colours performed significantly better with the IRR paint when to HBU
  • The HBU on the white control sample was 22.33 oc compared with 42.44 on painted black, which reduced to 24.91 when IRR pigments were used.


The popularity of coloured windows and doors continues to grow at a significant rate, and recent colour trends for grey, moving into deep, rich colours in the future, will only accelerate this growth. However, there is a risk that the UK fenestration industry is sleepwalking into a future issue, as dark coloured windows and doors absorb heat and suffer as a result of HBU.

We are already seeing moves, particularly form within the reinforcement industry, to counter this with a return to metal reinforcement. This will help, but it deals with the effects of the problem, not the problem itself.

In order to prevent the problem rather than just cure it, the solar reflectance of coloured windows and doors needs to be raised. Thanks to RegaLead’s experience in the North American markets, where IRR paints are now commonplace, and based on our extensive laboratory testing, the company will now be offering IRR pigments in all colours across ColorSpray GRP and Aqua paints.

For more information or for full copies of the Test Results, call RegaLead UK on 0161 946 1164 or RegaLead Canada on +1 905 264 1550