Exterior Colour Design:
This CPD unit explains some aspects of choosing colours for exteriors that might be new to you and useful in achieving the results you want.
some guidelines for exterior colour choice
|The image we're looking at here is Luis Barragán's 'Fuente de los Amantes. He once said that light and water were his favourite themes. Barragán (1902-1988) was one of Mexico's most influential 20th century architects. He transformed the International Style by adding vivid colours and textural contrasts that accentuated his buildings' natural surroundings.
We'll look at:
- How colours look outside
- Traditional colours
- The colour identity of an area and its surroundings
- Colour ranges for exterior coatings and surfaces
- Understanding the properties of colours
How colours look outsideInherent and perceived colour.
|The perception of façade colours is not constant. It changes with the position of the observer, the distance, the weather, the season, the light, etc.
This is the University of East London by Edward Cullinan Architects. The image illustrates the affect of surroundings, weather conditions, and light on the colours we see.
These two slides show the Frank Lloyd Wright house 'Falling Water' in four different seasons:
The house is often cited as one that sits well in its environment and you can see that it does this regardless of season. Part of this is due to the choice of colour for materials and the areas that are painted. Nevertheless the colours do look quite different. I've mentioned the different seasons – which must affect the light – but can you think of any other factor that affects the appearance of the colours in these images? (Surroundings – green of foliage).
|This diagram is adapted from an interesting book 'What colour is the red house' by Karin Fridell Anter.
It illustrates the factors affecting the perception of colour outside. You'll see there are a number of possible factors.
Light conditions and surroundings both altered the perceived colour in the Falling Water slides – also the inherent colour, the actual colour used.
Other factors might be:
- Viewing distance
- Observation angle
- Observer – physical or cultural or other factors the observer brings to what they
- Size and shape of the structure
- Gloss and surface texture
|The most common phenomenon to do with colour perception is that we think the colours we see are lighter and brighter than they actually are: less black and more chromatic. A colour that may be considered slightly dull on a sample card will look stronger and lighter on a façade. We can demonstrate the principle of this without going outside at all.
It is almost inevitable that the colour selected from the fan deck will be lighter and brighter. Usually it takes two steps to arrive at the right colour – and this will usually involve placing the fandeck right on the sample, with no space between and masking out any other colours.
The mask can be black or white or a neutral grey. It doesn't have to be fancy. I sometimes use two black photographic mounts that I can move to create a larger or smaller aperture. You might also use an instrument like the NCS Colour Scan to determine inherent colours on site. These operate with their own light source so can be used regardless of ambient light.
These are colour samples from a study where a number of architects were asked to make judgements about the colour of buildings from a distance (the perceived colour) and then to match the actual, inherent colour by putting colour samples against the surface.
Based on these research examples you will see that in addition to a shift towards lighter and brighter the hue of the colour has shifted. In some cases this is by one hue step around the colour circle but in others by three hue steps. The changes in perception are shown on the small triangle and colour circle diagrams and in the NCS references:
NCS S 1010-Y10R > S 0510-Y (5% less perceived blackness and 10% less perceived redness)
NCS S 1020-Y20R > S 0520-Y10R (5% less perceived blackness and 10% less perceived redness)
NCS S 2030-Y20R > S 1030-Y20R (10% less perceived blackness)
NCS S 3010-Y70R > S 2010-R (10% less perceived blackness and 30% more perceived redness)
NCS S 2010-R90B > S 1020-R80B (10% less perceived blackness and 20% less perceived redness)
NCS S 3010-G20Y > S 2010-B90G (10% less perceived blackness and 30% less perceived greenness)
The only general rule is one of less perceived blackness but the possible change in perceived hue is useful to know about and to test for prior to specification.
|Simultaneous contrast - Grey examples
The colour of the surroundings will have an effect on the perceived colour of a building. We saw this in the Falling Water slides and it is illustrated in two of our NCS colour exercises. The first one illustrates simultaneous contrast in lightness, where the grey colours that look the same on a white or black background are quite different when seen together.
First you create a grey scale with colour chips and put a larger white and black chip on the side. Next you take the fifth grey chip, cut it in half and put half on the large white chip. Then see which grey chip looks the same when it's placed on the black chip. You can see from the two gaps in the grey scale that it's the seventh grey that looks the same on black.
|Simultaneous contrast - Terracotta examples
The second exercise illustrates simultaneous contrast where perceived hue, whiteness, blackness and chromaticness are all changed by the background of the sample – the sample in the centre is the same in each case.
It's not always easy to demonstrate these exercises on a screen but you might be able to see that in the first example the right hand terracotta chip looks more red, less orange. In the second it looks lighter. In the third it looks darker, and in the fourth it looks stronger.
|Simultaneous contrast - Blue / Green examples
In this example the blue/green sample in the centre looks more green against a blue background and more blue against a green background. This is because our eyes try to identify and reinforce the difference between the two samples so that the difference is exaggerated.
We are all aware of the change in perceived colour over longer distances. We see it frequently in photographs or when we look out over a distance of hills and trees. In a study carried out to plot the changes seen in the colour of trees with distance the results in this diagram were seen:
In a study carried out under the direction of Anders Hård at Leksand Colour School in Sweden the NCS colours indicating the changes in perceived colour over distance changed from a strong green close up, becoming a softer darker blue green at 2km to a lilac grey at 20 km. Anders Hård was one of the founders of NCS, with Lars Sivik.
The diagram is part of this study and shows the changes from a fairly clean chromatic green through deeper blue greens to a lilac grey plotted on the NCS Colour Triangle and Colour Circle.
Since many buildings appear in surroundings of natural vegetation it is useful to know a little more about the inherent colours of nature and the NCS System can be useful in mapping, analysing and plotting these colours. All natural green inherent colours have some yellowness and tend to have hues G40Y and G50Y and nuances 5040 to 6030. However we have seen how green colours become more blue as the viewing distance increases – so if you want your green building to look green at a distance a more yellow green hue should be chosen.
Distance also affects how light and dark colours are perceived, regardless of hue. The difference in lightness between a building and its surroundings is probably the most important factor contributing to recognition of its form, particularly at a distance when difference in hue may not be so apparent. Think of the white cottage on the hill – or in this case Le Corbusier's Villa Savoye.
Even at close range the difference in lightness between colours is important for defining different parts of a façade. You can just see the lower part of the building is painted quite a deep colour to give the impression of the upper part floating.
|The lightness of a colour can be determined by comparison with a grey scale, or by measurement – it is not the same as whiteness. The word 'lightness' refers to either Light Reflectance Value (LRV) which is a measured value, or Visual Lightness (v) which is how we see lightness with our eyes. While the lightness of colours might be chosen for their aesthetic effect in many situations both the Light Reflectance Value (LRV) and Visual Lightness (v) of the colours must be considered to comply with regulations regarding access and LRV alone regarding heat absorption.|
This is a scale of 18 neutral greys from white to black with the visual lightness (v), light reflectance value (LRV) and NCS colour reference printed below each sample. The samples are mounted in apertures so that any colour can be judged. In this case the grey second from the left balances in lightness with the colour behind. 0.60 is the visual lightness and 33.89 is the LRV. It's worth pointing out here that the middle grey S 5000-N has a visual lightness of 0.5 as you would expect, but an LRV of only 25.91.
A scale of lightness and light reflectance values is shown on the white to black axis of each hue page in the NCS Atlas. The line that's highlighted is visual lightness 0.5 and LRV 26. The NCS Triangles also show a scale of blackness and a scale of chromaticness. There is a page like this for each of the 40 hues around the colour circle. Colours with the same saturation are found on a straight line through the black point. So all the properties of a colour can be known.
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NCS – Natural Colour System®© property of NCS Colour AB, Stockholm. References to NCS®© are used with permission from NCS Colour AB.