Thursday, 29 March 2012

Opening glass rooflights

One of the biggest advantages of installing our rooflights into your flat roof is to harness and utilise daylight, which can transform a dark and dingy space into one which is wonderfully naturally lit.

An example of a flat roof kitchen extension naturally lit by our glass rooflights - click to enlarge
Another consideration when specifying and choosing our rooflights is whether to opt for fixed or opening - and we have many opening options for you to choose from.

Our rooflights are supplied hinged to either the fully insualted upstand or fit adapter and so we always offer hinged opening as an optional extra. Our rooflight design also means that we do not need a bulky base frame for our opening rooflights and so our opening rooflight profile is exactly the same slender height as our fixed rooflights and so side by side on the roof, our fixed rooflight is visually identical as our opening ones.

When specifying an opening rooflight for a flat roof - it is important to ask all suppliers for proof of their airtightness values, otherwise even the most thermally optimised aluminium framework is a complete waste of time and money, if all of your heat is allowed to leak through a poorly sealed product. All of our standard aluminium framed rooflights are certified in accordance with EN 12207 to Class 3 (1.87m³/h/m² at 50 Pascals). Airtightness is going to become an even more important consideration next year when the revised Part L 2013 building regulations are introduced. We shall be posting a Blog entry on the airtightness of our rooflights very soon - so please check back or subscribe to our blog.

Our manually hinged version is suitable for rooflights up to 1 x 1 metre and will open the rooflight to around 300mm via a surface mounted screw-jack and operating pole:

Manually hinged opening for ventilation - click to enlarge
We also have electrically hinged opening options, to suit all budgets and aesthetic requirements and these are explained below.

The first of our electric hinged options is actuated by a 230v motor which has a stroke (opening) length of 300mm. The motor is surface mounted and is our most cost effective electrical hinged opening option at an optional surcharge of around £175 compared to our fixed rooflight price:

230v electrically hinged opening for ventilation - click to enlarge
If you would prefer a more slim-line style motor we can supply a chain motor (24v or 230v) and these are offered with a stroke length of either 250mm or 400mm:

Electrically hinged via chain motor - click to enlarge
The chain motor can also be concealed behind a powder coated (any RAL colour) cover flashing - see below:

Chain motor concealed by powder coated flashing - click to enlarge
The ultimate electrically hinged opening rooflight is our hidden chain motor option. This version has a chain motor concealed within the aluminium framework and the cable for the motor is routed though our insulated upstand - giving the sleekest possible looks:

Chain motor totally hidden in the rooflights framework - click to enlarge
All of our electrically hinged opening rooflights can also be supplied with a choice of sensors including; remote control operation, rain sensor and combined wind & rain many more.

If it is roof access you require then DVS has options for this too:
  • Manually hinged opening.
  • Electrically hinged opening.
  • Electrically sliding opening.
Please refer to our news article entitled "Roof access - aesthetic, efficient and functional" (coming soon!) which explains these options in more detail.

Thank you for reading - please feel free to leave a comment below or contact us for more information by phone 01284 749051 or via email

Wednesday, 28 March 2012

Isothermal diagrams explained.

Isothermal lines indicate points in a structure featuring the same temperature and reveal a measurable customer benefit in a thermal diagram. As a result, isothermal characteristics are increasingly shown by manufactures to provide proof of effective thermal insulation.

However, colourful charts do not always actually mean anything. To ensure that the diagram is relevant:
  • The diagram must clearly state what particular general conditions (1) the calculation were based on.
  • The 10° isothermal line, a variable used in building physics must run through the structure as a steady, flawless outline. This is the only way to guarantee that the risk of condensation is minimised under the specified conditions.
It is only then that reliable evidence can be provided of thermal behaviour and, consequently, of the structure elements real energy efficiency rating.

Isothermal diagram example:
Isothermal diagram of our triple glazed F100 rooflight dome
Isothermal characteristic of a 10° isothermal line (shown in red), in a triple glazed F100 rooflight dome, under specified boundary conditions. The isothermal line is featured as a steady outline within the structure – the risk of condensation is minimised.

The interaction of energy between individual system components, a crucial factor in determining the Uw value, is clearly visible in isothermal characteristics.

To ensure that the rooflights you are specifying comply with Building Regulations Part L – be sure to ask your rooflight supplier for their Uw values (calculated to EN ISO 10077) and check that any colourful diagrams supplied are actually substantiated by the inclusion of the 10° isothermal line and qualified general conditions.

Inside temperature +20°C, outside temperature -5°.
Analytical models for calculating thermal bridges: EN ISO 10211-1, EN ISO 10211-2, EN ISO 10077-2 and EN 13947. Materials: EN ISO 12524, EN ISO 10077-2, EN ISO 6946 and EN ISO 673; Boundary conditions: EN ISO 6946 and EN ISO 10077-2

Tuesday, 20 March 2012

Need a rooflight in a hurry?

We now offer a full online ordering facility for our F100 rooflight domesdelivered within 24 hours of order.

Our rooflight domes are supplied with triple skin glazing, a fully insulated 150mm high upstand and all have Part L compliant total product U-values, making them the ideal rooflight solution for residential, school and administration buildings.

X-section through rooflight: click image to enlarge
We hold stock of the F100 rooflight dome in 8 popular sizes, and all can be supplied either as a fixed or hinged opening rooflight.

Your rooflight order will be carefully packaged and dispatched to ensure that it reaches you in optimum condition.

Some examples of stock packaged and ready for dispatch - click photo's to enlarge.
We offer 3 options for delivery: 
  1. Collection in person from our factory in Suffolk
  2. Standard next day delivery.
  3. Economy delivery 2-3 days.
Orders placed before 12 noon will be dispatched the same day for next day delivery, orders placed after 12 noon will be dispatched the following working day.

Our total product U-values are all calculated according to the international standard EN ISO 10077-2 and are therefore completely substantiated.

Isothermal diagram of triple layer F100 dome - click image to enlarge.

All rooflights are supplied factory assembled and mounted to the insulated upstand, making installation very simple. The glazing is opal, to ensure dazzle free optimum diffused daylight distribution.

Opal glazing ensures dazzle free optimum diffused daylight - click image to enlarge.
For items that are out of stock or for larger orders & other sizing requirements (40+ other standard sizes available, to order) – please contact our dedicated sales team on 01284 749051 or email.

Order in confidence today, as all debit/credit card transactions are securely handled by PayPal with 168bit SSL encryption (the highest level of protection commercially available).

To have a look at the online ordering webpage please click here: ONLINE SHOP, and if you have any questions or can't find what you're looking for please call: 01284 749051 or email.

Friday, 16 March 2012

Uw value – the value which really counts.

The continuous improvement of U values in rooflights very much favours sustainable construction, although it does pose a problem regarding communication to the market, Daniel Boughton of Daylight and Ventilation Solutions Limited (DVS), explains why it is the total product U-value (Uw value) which really counts.
Our rooflights are supplied with verified total product U-values
Many sales arguments and advertising indiscriminately state Ug values, or often a U value which is not a standard certification designation. So, which particular thermal transmittance coefficient value is appropriate for determining a buildings energy balance?
According to the ift Rosenheim, in its capacity as an internationally recognised independent research institute, the following answer was given by Konrad Huber, their Head of Heat and Light Engineering Laboratory:

“The thermal transmittance coefficient Uw indicates the main influence on a buildings energy balance and thermal comfort”.

If this is so evident, why is it not standard practice to clearly and transparently communicate a system components Uw value? Why do advertising and price lists often rely on U or Ug values (according to BS EN 673) to present their sales arguments? The reason is quite simple: the Ug value (the thermal transmission coefficient of the glazing) is often lower that the actually relevant and meaningful Uw value and thus more advantageous for manufacturers for advertising purposes.

So, how is the Uw value calculated? Konrad Huber at the ift Rosenheim provided the following information:

“The Uw value basically consists of the thermal transmittance coefficients for all components in a light architecture element, i.e.: the Ug value for the glazing and all the Uf and ψ* values of all bar, frame and surround profiles in the system. All of this is then related to the surface area to give the Uw value, which is appropriate value for the thermal rating”

*ψ(psi) = linear thermal transmittance coefficient.

This means that the whole structure must be taken into account when making calculations. Here are the calculations for DVS’ barrel vaulted (continuous) rooflight, as an example: 

Uw value calculation example (click to enlarge)
Only by asking all rooflight manufactures/suppliers for their products Uw value – will you be able to make a direct comparison using the internationally recognised thermal coefficient value.

Continuous rooflights case study (Godalming)

Daylight & Ventilation Solutions Ltd (DVS) recently completed the installation of 312m² of continuous barrel vault rooflights in just 3½ days onto a new build equestrian centre in Godalming, Surrey.

3 x 48 metre continuous rooflight to riding arena.
DVS are the exclusive UK distribution partner for the German rooflight manufacturing company Lamilux GmbH. DVS’ managing director, Daniel Boughton is delighted to report upon the successful completion of its first major UK installation project of its continuous rooflight system.
The indoor riding arena measuring 20 x 60 metres has two adjoining 21No stall stable block wings, and each of the buildings benefit from natural daylight and ventilation from large continuous rooflights installed onto the roofs ridge. Each of the stable blocks has a 3 x 28 metre rooflight and the riding arena has an impressive 3 x 48 metre rooflight.

Low-profile barrel vaulted rooflight - spanning 3 metres

Daniel explains “We worked closely with the architect and main contractor to ensure that the desired levels of daylight, solar protection, heat insulation and ventilation were achieved and this was realised by specifying our continuous rooflight glazed with 16mm 6-ply multi-wall opal polycarbonate sheets”,  he added, “This particular specification offers a Ug (glazing) value of just 1.8W/m²K and because of our thermally optimised frame profile we could offer the assurance of a verified total product U-value of 2.0W/m²K”. 

Natural ventilation was also a very important consideration for this project and Daniel confirms how this was achieved “We supplied 4No. 1.2 x 2 metre electrically opening ventilation flaps per rooflight. Each of the opening vents is actuated via a 230v motor with 300mm stroke length”, he continued,  ”we also supplied our ‘weather pack’ which consists of a combined wind and rain sensor – so any open vents will automatically close in the event of high winds or rain”.

The building’s gluelam roof structure is clad with 80mm Kingspan insulated panels, and the rooflights were installed onto the weathered timber upstands.

Commenting on the speed and efficiency of the installation Daniel said, “The Lamilux continuous rooflight system is extremely well designed and is delivered to site completely factory prepared. It is a dry system with the glazing sheets perfectly tensioned in place with our patented aluminium glazing bars, meaning that installation is not affected by the sometimes inclement British weather.”

The base profile of the continuous rooflight is fabricated from uPVC, it is possible to use this material with excellent heat insulation because of the unique Lamilux isothermal load converter (ILC), Daniel explains “The ILC channels the load on the continuous rooflight into the supporting structure. This keeps the base profile free of loads and torsion, thus enabling the use of materials with excellent heat insulation properties. ILC technology means that we are able to guarantee optimised temperature patterns and ensure condensation risk on the base profile is significantly reduced.”

Isothermal Load Converter (ILC) - in detail.

Lamilux have been designing and manufacturing rooflights since 1955 and with a far reaching network of distribution partners in over 20 countries, their products are used on a very wide range of international projects.

Lamilux are setting the standard for continuous rooflights right across Europe, they are in fact the first and only manufacturer to achieve European Technical Approval for a continuous barrel vault rooflight (EOTA ETA-09/0347); thermal protection properties, water tightness, resistance to wind and snow loadings amongst many other criteria, are all tested and certified within this European Organisation for Technical Approval documentation – giving complete peace of mind to the roofing contractor, architect and building owner.

For more information about DVS please visit: