Colorcoat® Column: Colour and gloss retention

Colour and gloss retention of pre-finished steel are not only aesthetic requirements, they can often be used as indicators of the durability of a product as they are the first signs of coating failure. To understand this, it is important to detail the ageing process of coatings due to exposure to sunlight and how they can be assessed using both natural weathering exposure and accelerated testing.

Product durability can be defined by the ability of the pre-finished steel to withstand attack from a number of different sources including:

1. Water, oxygen, and salts
2. Chemicals
3. Abrasives
4. Sunlight

The ultra violet light portion of the sunlight spectrum is the most destructive to organic coatings as it is directly absorbed at the molecular level by the coating.

What are the effects of exposure to sunlight?

When exposed to sunlight, organic paint systems show a number of reactions indicating that the coating is being affected. These occur in the following order:

1. Loss of gloss or surface shine of the paint. This occurs as the surface breaks down and roughens slightly leading to surface scattering of the visible light.
2. Colour fade due to pigment degradation and surface chalking.
3. Micro-cracking and embrittlement of the paint surface.
4. Total coating failure in terms of localised cracking and peeling of the paint, and in worse cases delamination from the substrate leading to expensive repaint or re-sheet.

The time taken to progress through these to coating failure depends on the pre-finished steel coating, more durable paint systems, which have excellent colour and gloss retention, have better resistance to sunlight and so will last longer.

How is colour and gloss retention assessed?

Product performance can be assessed by a combination of accelerated laboratory testing, accelerated natural exposure  (EMMAQUA) and natural exposure at a range of weathering sites world-wide, which have different climatic conditions.

EN10169 defines the test methodology and classification standards. For UV resistance, products can be classified from RUV1 to RUV4 (most durable) – Colorcoat HPS200 Ultra® and Colorcoat Prisma® both exceed the requirements for RUV 4 classification.

Colour and gloss retention are only one factor to consider when looking at the overall durability of pre-finished steel. Corrosion resistance of the substrate, particularly at the cut edges and abrasion and scratch resistance of the paint coating are also key parameters. The best pointer for durability is the guarantee period and coverage, e.g. does it include cut edges.

Colorcoat® Column:Integration of rooflights with pre-finished steel cladding systems

In-plane rooflights can easily be included into profiled pre-finished steel roof systems requiring no modifications to the secondary steelwork and can supply light deep into large single storey buildings. Natural lighting, as well as providing benefits to the building occupants, can reduce energy costs and CO2 emissions, provided a balanced approach is taken to solar gain, heat losses and lighting levels.

What factors do I have to consider when installing rooflights?

The building designer needs to consider each building individualy as the operating conditions and building construction can greatly affect the requirements.

Rooflights can provide very significant savings in artificial lighting and associated CO2 emissions but only if they are installed in conjunction with an efficient automatic control for the electric lighting and cleaned on a regular basis.

The U-value of rooflights is significantly worse than the surrounding insulated cladding and more heat can be lost through the rooflights than through the entire insulated roof cladding. This has to be balanced against useful solar gains and reduced artificial lighting requirements.
Higher performing rooflights are available which can significantly reduce heat losses, however these are more expensive and this needs to be balanced against saving from other building envelope or service enhancements.

24 hour operations and introduction of high bay racking, within a building will greatly reduce the effectiveness of rooflights and increase use of artificial lighting.

How do I take these factors into account when modelling the building?

The introduction of rooflights can have a very significant effect on the CO2 emissions of a building, both in terms of compliance with Part L and actual building operations.

SBEM using the national calculation methodology (NCM) is a Part L “compliance modelling tool” and should not be used for “design modelling”. It calculates the CO2 emissions for an empty building using defined operating parameters. These parameters may be very different from those under which the building will actually operate and the results may therefore be quite different from operational performance. The NCM does allow direct comparison of the performance of similar buildings and this can be used to calculate energy performance certificate ratings for the buildings.

Where hours of operation and operating conditions are significantly different from those defined in the NCM and where high bay racking is likely to be installed, it may be beneficial to carry out specific design modelling to optimise lighting parameters for the actual building operations.

Even when specific “design modelling” has been undertaken it is a requirement of Approved Document L to meet the criterion for CO2 emissions which must be done by compliance modelling using the NCM.

Visit the Colorcoat® Technical Papers section on colorcoat-online for papers on Part L Compliance and Rooflights.

Colorcoat® Projects on Google Street View

My Dutch collegue has just sent across two links to Google Street View which show two projects featuring Colorcoat® products…

The first is Het Strijkijzer. Modelled on the famous Flat Iron building in New York, this building makes full use of Colorcoat® products in various profile configurations:

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The second is Waterwongingin Blaue Hart:

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Finally, i’ve had a quick look on street view and found the Ikea Store in Coventry, which uses Colorcoat Prisma® – go ahead, have a look around…

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Have you spotted any of your own projects in Street View that use Colorcoat? If so, show them off by posting a comment below…

Corus Colors wins at BEMA

Corus Colors has won the award for best campaign under £25k at this years BEMA awards. The Education campaign, focussing on pre-finished steel solutions for Educational buildings incorporated a series of print ads, a comprehensive brochure and a dedicated mini-site. To view the Education mini-site, click here.

About BEMA

The Built Environment Marketing Awards are an opportunity to compete against the best in the construction industry. The awards recognise creativity, innovation and effectiveness for marketing and business development in the built environment. For more information, click here

SolarWall® In Action Event – Comment by Stephen Fisher, Corus Colors

Stephen Fisher, Market Development Manager at Corus Colors, gives his take on the recent SolarWall in Action Event at the British Motor Heritage Museum….

Free heating, reduced fuel bills, reduced CO2 emissions, improved BREEAM ratings, excellent ventilation properties. Music to the ears of any building owner. Acting as a third skin to the building fabric, SolarWall® is a perforated Transpired Solar Collector which harnesses solar radiation to heat ambient air via a perforated collector.

Solar heated air is drawn from the external surface of the collector, through the perforations, before being distributed into the building where it is used directly as building ventilation or as a pre-heater for the building’s main heating system- reducing the amount of energy required to heat the building and associated CO2 emissions. New build and retro-fit buildings can utilise the technology which uses Corus Colorcoat Prisma® pre-finished steel. The level of initial interest for the SolarWall® product has been high.

Every time I have presented the offering alongside the Colorcoat® branded product offering, I have been met with requests for more information from the customer, or further meetings, to enable their other team members to hear about the benefits the CA Group product can bring to a project. So it was no real surprise to me that at the Motor Heritage Museum at Gaydon, venue for the SolarWall® in Action day this month, attendance figures were 40% over capacity. Representatives from a number of high profile clients, some of Europe’s biggest main contractors, along with developers and construction consultants were in attendance.

Some had heard of SolarWall® in part, others were new to the concept. The networking over with, the main presentations got underway. Peter Strikwerda, MD of Corus Colors, welcomed the audience and opened the proceedings with an insight into how both Corus and CA group were approaching the sustainability agenda. Kevin Bygate, Director of Product Development for Corus Colors, then set the scene as to why Corus and CA Group were so well aligned and had teamed up to help bring this particularly innovative venture to the market. The over-riding reason being a common understanding for the need for better performing buildings for future generations. Then it was the turn of Brian Watson, Commercial Director for CA Group, who took the audience through how SolarWall® works and the numerous benefits it can bring to a building. What struck me here was the amount of independent third party evidence which backed up the claims being made by the speaker. Reports by BSRIA, Battle McCarthy and the Swavesey report emphasised the benefits which SolarWall® delivers in terms of both energy savings and renewables (costs, percentage achieved etc.) The case studies presented at the end of the presentation also successfully demonstrated this. As I looked around the room I was greeted by the sight of an audience captivated by what they were hearing, the vast majority leaning forwards in concentration.

After presentations by Jaguar Land Rover, who are using SolarWall® on the nearby JLR Academy, and a short Q and A session, the audience were afforded the opportunity to see the system first hand and witness the energy savings it has bought to date, live, through monitoring equipment installed at JLR. The proof is in the pudding as they say. Listening to feedback on the way to the Academy, the information delivered so far had obviously been well received, comments such as ‘I’m seriously impressed with the payback time’ and ‘I will be looking to put it forward as a generic spec for my future buildings…’ was a testament to that. The tour itself only served to confirm what people had heard about SolarWall® earlier. The improved air quality in the building itself was a comment I heard several times throughout the visit. This coupled with evidence of the energy savings for the building seemed enough to have many people seriously thinking about the bonuses a system such as SolarWall® could provide to their building stock.

All in all the day itself was a huge success with numerous follow up meetings being made with interested parties with a view to lock SolarWall® into a number of project specifications. And with so many positives it is hard to argue against the offering.