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Daylight design considerations for rooflighting in commercial developments

There are many design considerations with regard to specifying rooflights within commercial buildings for daylight, which are influenced by such factors as:


  • The building’s orientation and intended geometry
  • The geographical location of the building and seasonal variations in daylight/ sunlight (and temperatures)
  •  The presence of potential shading from adjacent buildings or other obstacles, which might compromise the daylight coming in from vertical windows
  •  The need to meet Building Regulations, in particular the requirements for energy performance as well as EN 17037.
  • The desire to achieve LEED/BREEAM certification
  •  The building’s thermal insulation and the heating and cooling system installed
  • The need for control mechanisms to allow for easy ventilation, potentially smoke ventilation
  • The need to control glare from direct sunlight, and the use of blinds (or shading)
  •  The roof construction, and pitch, and the intended size and location of rooflight apertures
  •  The potential requirement to integrate the rooflights into the BMS
  • The intended aesthetics and vision for the building
  • The intended use of the commercial space i.e. office, manufacturing, education etc.


As the narrative about the ‘Indoor Generation’ gains more traction, those involved in the commissioning of a new commercial building, or indeed the refurbishment of an existing building, are becoming increasingly aware of the benefits for occupants of creating vibrant, healthy spaces, which provide greater access to natural daylight and fresh air.


This article will outline how rooflights can contribute significantly to a daylighting strategy in commercial properties, by providing even and consistent daylight, especially deep within large buildings, thereby ensuring occupants enjoy a comfortable and pleasant work environment.

Why is daylight so important in the design of commercial buildings?

Our acceptance of offices and other commercial buildings is becoming increasingly dependent on the extent to which they provide us with contact with the outdoors. Access to sunlight in the workplace and the opportunity to experience seasonal changes in daylight as well as to enjoy well-ventilated indoor spaces have all been cited in numerous international studies as being highly valued by office workers.


Today, long hours spent in the office, oftentimes in dark, poorly ventilated and unhealthy buildings, are impacting significantly upon our sleep patterns, upon our ability to concentrate, upon our productivity levels, and ultimately upon our physical and mental health. Our physiological systems, especially our body’s circadian cycles, are being disrupted by a lack of exposure to natural daylight and a “divorce” from the outside world. Without exposure to sufficient levels of light in a building, reported to be around 1,000 lux, our brain is less stimulated, and our energy levels hugely affected. Our mood, how we interact with our colleagues, our cognitive performance – these are all influenced by how much we are exposed to natural daylight.


Investing in good office design to create bright, thermally comfortable and healthy offices has been proven to be sound business sense. Indeed, companies have recorded around a 15% increase in productivity in their staff after moving to a new building with better daylight conditions (Edwards & Torcellini, 2002).


Good daylighting design is also key to delivering significant energy efficient lighting solutions for commercial buildings. Natural daylight is a free resource and costs nothing to the environment. As part of a buildings lighting strategy, using roof glazing in combination with façade glazing, artificial lighting solutions and lighting controls to maximise the levels of daylight coming into a building can reduce reliance upon artificial light, lower electricity usage and lead to greater energy savings. However, the risk of solar over-heat must be controlled in order to prevent building occupants becoming uncomfortable. Openable roof lights can provide appropriate levels of ventilation and can be integrated into the BMS.

Satisfying the EN 17037 daylight standard

The introduction of EN 17037 has not only led to a change in how buildings are designed in order to incorporate more natural daylight, but it has also highlighted the role that glazing can play to improve occupant comfort and overall energy efficiency. EN 17037 stipulates that the need to provide glazed openings and well-distributed daylight to interior spaces, whilst reducing artificial lighting in use, must be considered with the balance between heat loss and solar gains.


This new standard has extended the scope of “best practice” when designing a daylight strategy for a new or an existing commercial building. It is not just about the “art”, but more about the “science” of designing daylight, as EN 17037 sets out important criteria that need to be met.


How can rooflights achieve the needs of commercial buildings?


The integration of rooflights into a building’s design can offer several real benefits.

  • They can contribute to an effective technical lighting scheme, especially when combined with efficiently controlled artificial lighting, to produce the appropriate level of illumination for particular tasks.
  • Rooflights can enhance the more subjective qualities of spaces as part of the building’s architecture. They lend a light, spacious feel to open-plan, flexible working arrangements in offices.
  • They deliver those all-important sky-only views that are key to providing the building’s users with a feeling of being connected with the outside world and to help to promote a sense of wellbeing.
  • Rooflights can be installed strategically, especially in large buildings, to maximise the light falling into deep, corner spaces, which might otherwise appear dark and shadowy. The provision of sufficient daylight in such areas is also crucial for the safety and efficiency of the building users.
  • Rooflight systems offer modularity to deliver bespoke, large-scale glazing solutions over communal areas in commercial buildings such as atria, feature staircases and circulation ‘arteries’. These rooflight structures not only maximise daylighting but they can enhance the architecture of a building and compliment the modern aesthetic.
  • Diffuse daylighting via rooflights can allow offices to operate during daylight hours without or with reduced artificial lighting, leading to greater energy savings. This is an important benefit in the computation of the energy efficiency of a building, and compliance with Building Regulations.
  • Venting rooflights, especially those operated through the BMS, can play a key role in the ventilation strategy of a commercial building, and facilitate a reduction in reliance on HVAC systems.


How to choose the right rooflight for a commercial building?

Identifying the most appropriate rooflight solutions, that meet both the technical as well as the aesthetic requirements for the project, can be a challenge to any architect, given the multitude of products available in the marketplace. Just as rooflights can differ in their size and specification, so too do the effects on the building and the occupants below. Seeking the advice and involvement of manufacturers’ technical experts at the outset of the design process is therefore crucial. Close liaison ensures greater understanding of how the building should look and operate, how rooflights can be problem-solvers in key areas of the building, and how they can be used to enhance the design aesthetic as has been envisioned by the architect.


At Xtralite we are specialists at designing with daylight and the company was the first rooflight manufacturer to have its products environmentally profiled. Now part of VELUX Commercial, our combined knowledge and broader portfolio of commercial daylight solutions offers a one stop shop for design support and solution specification for your next project, including modular skylights, continuous rooflights, bespoke glazing panels, domes, and smoke and heat ventilation exhaust solutions.

Involving our experts at the initial phases of your design process helps greatly to create a design that is not only aesthetically striking but also technically efficient. Should you wish to discuss your project requirements please do not hesitate to contact Xtralite’s team of technical experts or simply download our Designing with Daylight brochure offering guidance on rooflight options and their features.

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