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Our Skyline Box range of glazing bars offer an economical roof glazing solution when compared with curtain walling roofing systems. The glazing bar's strength is provided by an internal box section. The glazing bar is weathered by a screw on pressure cap (PC1) with a choice of plain (PC2) or ornate (PC3) cosmetic outer snap-on cappings to conceal all fixing screws.



When used with high performance double glazing units with warm edge spacer bars and argon gas filling this system can achieve an overall U Value of 1.4W/ m²K to comply with Building Regulation Document L.


Our Skyline range of glazing bars offer an economical roof glazing solution incorporating slim sightlines. The glazing bar's strength is provided by an internal stalk (or fin) which is cut away at the top and bottom main fixing positions.
An internal snap-on ornate capping system (PC4) is also available if desired to fully conceal the internal stalk giving the appearance of a feature timber rafter.



When used with high performance double glazing units with warm edge spacer bars and argon gas filling this system can achieve an overall U Value of 1.4W/ m²K to comply with Building Regulation Document L.


Timber rafters (supplied by the builder or joinery sub-contractor) will create an appealing visual effect inside any home and are totally protected from the effects of weathering by our externally clad Rafterline Patent Glazing system.
Due to the pleasing aesthetics of aluminium and timber materials our Rafterline system is the most popular specifiers choice for domestic projects.



When used with double glazing and thermal breaks this system is easily capable of providing an overall U Value of 1.6W/ m²K to comply with Building Regulation Document L.


Our Traditional patent glazing system remains our customers most popular choice for use on unheated spaces such as Railway Stations, glazed canopies and covered ways where thermal properties are not a consideration.
This system has been installed on thousands of projects nationwide and is available with a choice of capping systems to suit your needs.
A truly great glazing system combined with economy and a proven track record. 30,000m² of this glazing system has been installed by us on many major railway stations throughout the UK in recent times.



This system is capable of accommodating solid or multi-wall polycarbonate sheets or double glazed units up to 28mm thick if used on unheated spaces or where compliance with Building Regulations Document L are not a consideration.


Our 'Heritage' Patent Glazing Bar range is truly unique amongst roof glazing systems; there are no alternative products available on the market which can match an original lead covered steel patent glazing bar which originates from the Victorian era. This range has been manufactured by us unaltered for over a century and is the perfect product for listed buildings and for use in the refurbishment of significant and historic buildings. This system is also still very popular for new build projects and should not to be overlooked on today's modern buildings where a unique character look is desired.

 


Various techniques are available to control the levels of solar heat gain (solar heat) passing through roof glazing, the most common being the use of solar control glasses. The following information is intended to provide relevant information concerning the use of glass as a means of solar control.

 

 
  • Intro
  • Basic Principles
  • Solar Control For Glass
  • Design
  • Performance Data for different solar control glass types

Rafterline Patent GlazingFigure 1. Light and Heat Transmission through a double glazed unit

 

In addition to admitting light, our roof glazing systems also allow the natural heat from the sun to enter a building.
During the winter this can be considered a benefit – offsetting heating costs by providing ‘free’ heat on sunny days during the heating season.
During the summer months, however, unless some form of solar control is considered, this heat from the sun could be regarded as a disadvantage.
There are several solar control glass types available with a large selection of performance levels allowing different amounts of light and heat transmission through the materials. This is achieved by using body tinted glass or special reflective coatings

 

Tynemouth Railway Station icorporating green body tinted solar control glass

Glass transmits solar radiation from the sun by three mechanisms, reflection, transmission and absorption, which for solar control purposes are defined in terms of the following parameters:

Reflectance:
The proportion of solar radiation at near normal incidence which is reflected by the glass back into the atmosphere

Absorptance:
The proportion of solar radiation at near normal incidence which is absorbed by the glass.

Direct Transmittance:
The proportion of solar radiation at near normal incidence which is transmitted directly through the glass.

Total Transmittance:
The fraction of solar radiation at near normal incidence that is transferred through the glazing by all means. It is composed of the direct transmittance, also known as the short wave component, and the part of the absorptance dissipated inwards by long wave radiation and convection, known as the long wave component. The proportions of the absorbed energy which are dissipated either inside or outside depend on the glazing configuration and the external exposure conditions (see diagram). All solar radiant heat properties are angle dependent.

Shading Coefficient:
The solar radiant heat admission properties of glasses can be compared by their shading coefficients. The shading coefficient is derived by comparing the properties of any glass with a clear float glass having a total solar heat transmittance of 0.87 (such a glass would be between 3 and 4mm). It comprises a short wavelength and long wavelength shading coefficient.

Solar control can be achieved by the use of:
- Body tinted glasses with increased absorption
- Reflective coated glasses with increased reflection
- Combinations of body tinted and reflective coatings in a single glass
- Special high performance insulating glass units

Body Tinted Glass
These types of glass are usually tinted grey, green, bronze or blue throughout their thickness. Their solar control properties and colour vary with thickness whilst their reflectances are slightly less than clear float. When used in double glazed units they are best positioned as the outer pane as the heat due to the absorbed radiation is more easily dissipated to the outside of the building.

Coated Glass
Solar Control can be increased by the use of coated glass which:

- Reduce solar heat gains with a full range of high, medium and low performance options
- Offer a choice of high to low light transmittances
- Provide varying degrees of reflectance including low reflectance
- Are available in a wide range of colours and appearances to meet aesthetic design requirements
- Are available as toughened or laminated options for safety and security
- Offer a comprehensive range of solar control performance options. The numerous coating compositions available provide a wide range of performances, which is further increased by their combination with body tinted glasses. Thus, glass with a particular performance may be selected for specific applications.

The design and specification of glazing demand that several (often conflicting) requirements need to be met, and it is impossible to consider any one in isolation. However, when considering the use of solar control glass, it is convenient to consider the local climate, which in the UK is temperate

Temperate Climates
Glass performance in temperate climates has to balance the need to provide solar control and reduce summertime overheating against the need to provide high levels of natural illumination and the benefits of passive solar heating. To allow for passive solar design, the performance range could be:
Total transmission 20% to 70%
Light transmission 35% to 90%
U value 1.0 to 1.2 W/m² K
These performance parameters for glass need relating to the specific application, since there is no one ideal glazing solution for all applications. However, as a general principle, high thermal insulation with solar control is a usual requirement for temperate climates such as the UK.

Solar Gains
Solar radiation through glass causes the air temperature in a room to rise, and it is the task of the designer to ensure that this temperature does not cause discomfort by specifying comfortable design conditions, and by providing appropriate plant and equipment to meet them. To this end, the designer will have to undertake calculations to assess the effect of various glazing options on the solar heat gains that his ventilation or air conditioning equipment need to cope with, and choose the best solution for the specific application in question. Solar radiation is not the only source of heat which contributes to the ‘total heat’ within a building.
Other sources include:
Conduction gains and losses through glazing.Ventilation by incoming warm air.
Internal sources of heat (by lighting, occupants and electrical equipment).
Solar gains into a building can be determined from a knowledge of the following:
The position of the sun in relation to each elevation of the building. Levels of solar radiation are dependent upon whether or not the sun is relatively high in the sky (altitude) and to the North, South, East or West (azimuth).
The intensity of The solar radiation incident upon The faces of the building.
The surface areas exposed to The sun. A large glazed area will potentially allow more solar gains to enter a building than smaller areas of glazing.
The date and time of day. This is related to the relative movements of the sun and earth.Shading effects. Presence of blinds, overhangs, nearby buildings etc., may prevent solar radiation entering a building.
Type of glass. Different glasses will transmit, reflect and absorb different proportions of the sun’s energy.
Structure of the building. A building constructed of heavyweight materials will heat up and cool down more slowly than one made with lightweight materials.

Direct Radiation and Comfort
Whilst air conditioning can provide comfortable conditions for the building and occupants as a whole, the effect of solar radiation falling directly on people situated close to the glazing needs to be treated separately. An occupant receiving direct solar radiation can feel uncomfortably hot even when room temperatures are being maintained at a comfortable level by means of air conditioning or mechanical ventilation. As a general guide, highly reflective glasses with relatively low direct solar transmittances will be most effective at combating the localised overheating of occupants situated under the glass.

   

The table opposite shows performance data relating to the most common solar control glasses available on the market.

The values are based on double glazed units incorporating inner panes of 6mm low e clear glass and the outer pane is as show in the table.

The first two items show information pertaing to clear glass (without solar control) to aid in comparison to the other products.

Even clear glass in a low e double glazed unit (which most people believe allows 100% of light through) actually blocks 22% of visible light from entering the building. This is worth bearing in mind when considering the correct product for your solar control requirements.

View in pdf format. Click here

   

The table opposite shows performance data relating to high performance neutral solar control glasses available on the market with normal lead-in times

The values are based on double glazed units incorporating inner panes of 6mm clear glass and the outer pane is as show in the table which has a low e coating incorporated into the glass.

These glasses are popular due to high light transmission values combined with a neutral tint rather than the body tinted coloured glasses available.

View in pdf format. Click here

   

The table opposite shows performance data relating to Pilkington high performance neutral solar control glasses.

The Suncool range is available in many different formats but is rarely used in roof glazing as the lead-in times for these products are usually unrealistic compared to the Sunguard Super Neutral range which is readily available in the UK.

Lead-in periods are usually 8 weeks or longer so very carerful planning with the programming of the project must be considered to enable these products to be used.

The values are based on double glazed units incorporating inner panes of 6mm clear glass and the outer pane is as show in the table which has a low e coating incorporated into the glass.

These glasses are desirable due to high light transmission values combined with a neutral tint rather than the body tinted coloured glasses available. Suncool is also available with a range of coloured coatings for aesthetic purposes.

View in pdf format. Click here