Roof windows are a great source of daylight
Studies conducted over the past two decades have shown that a lack of exposure to daylight has a wide range of negative consequences, from lower work efficiency and a higher incidence of accidents, to health problems such as malaise, lack of energy, insomnia, depression and some types of cancer. We spoke to Neža Močnik, architect at VELUX Slovenia, about providing natural light through roof windows, whether on a pitched or flat roof.
Daylight, fresh air and contact with the outside are becoming increasingly important parameters of quality of life. Roof windows have several advantages that make sense to use in rooms under a sloped roof. Can you briefly describe them?
The primary function of windows is to bring natural light into a space, and here lighting through the roof has a great advantage. If we compare an equally large facade window with a sloped roof window, the difference in lighting is twofold, due to the orientation of the roof window towards the light source. If we compare a space with a window on a flat roof, the amount of daylight coming from the top – I am talking about zenithal light – is up to three times greater compared to a facade window. roof windows are therefore an excellent source of daylight, which is worth using in spaces under a sloped or flat roof.
In winter, roof windows are an excellent source of heat, so it makes sense to install them in spaces in which the roof faces south. The sun is welcome in winter from an energy and mood perspective. Roof windows also help to cool the space in the summer months. Rapid air exchange in the space is achieved by simultaneously opening two windows at different heights. The greater the difference in height, the more effective the natural draft will be. Staircases are therefore ideal for taking on the function of cooling the home. With the help of effective natural ventilation at night or in the morning, by simultaneously opening windows, e.g. a roof window at the top of the staircase and an opposite facade window, it is possible to cool the indoor air in summer, thereby reducing the need for artificial cooling. Of course, in summer, roof windows need to be shaded in a timely and effective manner to ensure a pleasant indoor temperature, which is not a problem today with modern blinds.
In addition, the view to the outside is an important quality of space, which greatly affects the psychological well-being of the user, as it reduces the feeling of “closure” in the space. It is an important contact with the outside world, control over what is happening outside, the ability to monitor the change of day, seasons, view of the landscape. Roof windows can be combined in combinations to provide more daylight and a better view to the outside.
Is there any concrete research or data confirming that natural light has been proven to have a more positive impact on people’s well-being and health than artificial lighting?
We must be aware that Europeans spend almost 90% of our time indoors, of which we spend two thirds of our time at home. This is a telling fact that deserves thoughtful planning, both for new residential buildings and for the renovation of existing ones. With daylight, we can provide large amounts of light in rooms, daylight has an excellent spectral composition, and at the same time it also changes during the day. These are its main advantages.
By providing a sufficient amount of daylight, we not only ensure suitable conditions for performing visual work, but also influence the proper functioning of our circadian rhythm. The human biological clock (circadian rhythm) adapts to the day-night cycle and is largely dependent on the intensity of light, or the alternation of dark and light cycles. Therefore, humans need the alternation of light and darkness for normal functioning, especially for the secretion of hormones (melatonin, serotonin, cortisol).
What choice of windows and shading would you recommend for bedrooms where it is important to regulate the amount of light due to its impact on circadian rhythm?
We still come across the idea that bedrooms do not need a lot of daylight, but a bright bedroom will help us to drive away morning fatigue, because daylight increases the level of the hormone cortisol, which is needed for wakefulness.
In children’s rooms, we can see more often an intentionensuring that children have a sufficient amount of daylight. In addition to quality lighting, children also need darkness for a good night’s sleep. To provide darkness, an internal blind is used that does not let in light. This results in a fully darkened window. To prevent overheating in the summer months, an external mesh blind is used that also lets in light. This combination is especially welcome when roof windows are the only source of daylight in the room.
Darkness can also be provided in bedrooms with an external roller shutter, which will completely darken the roof window, and thus also protect the windows, especially those facing the sun, from overheating. This solves the need for darkening and at the same time protects against heat. The roller shutter also contributes to sound protection by muffling the sound of raindrops.
Working from home has become a part of everyday life. What solutions would you recommend for arranging a work corner to make the most of the benefits of daylight, such as better concentration, productivity and less stress?
To properly illuminate a work desk, it is necessary to pay attention to a sufficient amount of daylight and also to the direction from which it comes. In addition, it is crucial that the light does not cause glare on surfaces, which is very unpleasant and tiring for the eye. At the same time, we need a window at a height that will allow a view outside. This is important for relaxing the eye muscles. I should also say that employees achieve higher productivity at workplaces by up to 10% with a sufficient amount of daylight. A view of the green environment and natural ventilation also have a great impact on employee efficiency.
Many studies have been conducted on the impact of daylight on health and well-being, the most extensive of which are on the impact of daylight on students. It has been found that good daylight affects the health and concentration of students in class, and thus their learning progress and grades. Children’s learning abilities, for example, increase by up to 15%. In classrooms with the most daylight, students had higher grades by 7-18%.
However, behind the desks of children’s and youth rooms, we still find solutions with only one facade window. This greatly limits the placement of the desk and other pieces of furniture. If the room is also lit through a roof window, we immediately get a better distribution of light. The facade window can serve as a view outside, while the roof window provides a sufficient amount of light.
Do you think we often overlook the opportunities that skylights offer to improve living comfort on flat roofs?
Even spaces under a flat roof have limitations on how far daylight can reach, but at the same time there are so many opportunities for lighting through a flat roof. We can bring daylight into every space through a flat roof. In residential buildings, it is possible to illuminate spaces in the middle of the building, hallways, bathrooms, or add a window on a flat roof as an additional source of daylight. The zenithal light source is up to three times more intense than the facade light source, and this advantage should be used especially where we are limited by the amount of light. These are, for example, row houses, which have the possibility of lighting only through two facades. Daylight can be brought into the ground floor through the staircase. Public buildings such as schools and kindergartens have deep spaces. If we want to ensure at least approximately even distribution of light in classrooms or playrooms, it is necessary to think about lighting from several sides. With windows oriented to different sides and through the fifth facade – the roof, we also bring different light into the space during the day.
There are probably several reasons why these solutions are not used more often in the market. Sometimes you need to get the right inspiration, an idea and see what the effect daylight can make in a room. A flat roof window is much more than a classic acrylic dome. It is a window with energy-saving glazing, which has an aesthetic glass cover on the outside. The window can be equipped with a blind, which is almost always needed in living spaces. Installing a window is not difficult, it is necessary to carry out the details properly and carefully according to the instructions.
How can users effectively manage shading and ventilation in roof windows that are more difficult to access?
Electrified windows and blinds are available for easy operation. The window can be electrically or solar-powered, as can the blinds. They are operated via the included wireless switch. By pressing a button, we can simplify opening or closing the window. Electrified blinds are welcome when the window is out of reach, as we will actually use the blinds. With external blinds, it is especially important in the summer that they are lowered on time and thus adequately protect the room from overheating. Another advantage is the time setting for lowering/raising the blinds and remote control via an app on the phone.
In children’s rooms, where roof windows are installed out of reach, raising and lowering the blinds on a daily basis is difficult. Operation with a rod is possible, but in this case I would recommend an internal solar-powered blind. The blind is operated via a wall switch that operates on radio frequency, so no electrical wiring is required.
Are there solutions for situations where we leave a window open for ventilation and are then surprised by a sudden rain? How can we prevent potential damage?
Our electrified windows already have a built-in rain sensor, which ensures automatic closing in case of rain. This eliminates the need to worry about whether the window has been left open or not. Electrified products can also be controlled remotely, via an application on the phone, to which all electrified products can be connected. It may also be good to know that it is possible to upgrade an existing manual window with an electric motor. If it is not possible to bring an electrical cable to the window, a solar-powered motor is also available.