What Is A Daylighting in Construction?
What Is A Daylighting in Construction?
Daylighting in construction refers to the practice of designing buildings in such a way that they allow for maximum natural light penetration into the interior spaces, reducing the need for artificial lighting.
This can be achieved through the use of skylights, roof windows, light wells, or other design elements that bring natural light into the building.
Daylighting is the use of windows, skylights, other openings, and reflective surfaces to allow sunlight to provide natural light inside a building. This approach is often utilized in architecture and design to improve visual comfort and reduce energy consumption.
By utilizing daylight, the need for artificial lighting is reduced, leading to energy savings. This can be achieved through the installation of fewer electric lights in areas with sufficient daylight, or through the automatic dimming or switching off of lights in response to daylight.
The amount of daylight received inside a space can be determined through measurement or calculation. Computer programs like Radiance allow architects and engineers to easily evaluate the benefits of a particular design.
The human eye responds differently to light, so an even distribution of light can make a room appear brighter. The source of all daylight is the sun, and the proportion of direct to diffuse light affects the amount and quality of daylight.
Direct sunlight reaches a location without being scattered in the atmosphere, while diffuse daylight is sunlight that has been scattered in the atmosphere. Sunlight reflected from walls and the ground also contributes to daylight. Strategies for daylighting vary based on the climate and location, as each area has a different composition of daylight and cloud coverage.
On the polar side of a building, there is no direct sunlight from the autumnal equinox to the vernal equinox in latitudes north of the Tropic of Cancer and south of the Tropic of Capricorn. Historically, houses were designed with minimal windows on the polar side and larger windows on the equatorial side.
Equatorial side windows receive some direct sunlight on sunny days, making them effective for daylighting. However, during mid-winter at higher latitudes, light incidence is highly directional, creating long shadows.
This can be mitigated through light diffusion, light pipes or tubes, and reflective internal surfaces. In summer at low latitudes, windows facing east and west, and sometimes those facing the nearest pole, receive more sunlight than windows facing the equator.
Types Of Daylighting
Passive daylighting refers to a system of bringing sunlight into a building using non-moving, non-tracking fixtures such as windows, skylights, sliding glass doors, and light tubes. The collected sunlight is then reflected deeper inside with elements such as light shelves. This is distinct from active daylighting systems which track the sun and rely on mechanical mechanisms.
Windows are the most common way of admitting daylight into a space. They admit sunlight and diffuse daylight differently at different times of the day and year due to their vertical orientation.
To get the right mix of light for the building, windows on multiple orientations must be combined, depending on the climate and latitude.
There are three ways to improve the amount of light from a window: place it close to a light-colored wall, slant the sides of the window opening so the inner opening is larger than the outer opening, or use a large light-colored window sill to project light into the room. Windows not only admit daylight into the building but also provide views.
To enhance the quality of a window view, three primary variables must be ensured: view content, view access, and view clarity. View clarity can be influenced by shading devices used to protect occupants from harsh daylight or for privacy reasons.
Environmental criteria such as location, time, weather, people, and nature can be used to predict preferences toward different window views, with research showing that nature-containing views are most important.
Different types and grades of glass and window treatments can also affect the amount of light transmission. The type of glazing is expressed by its VT coefficient, which measures how much visible light is admitted by the window.
A low VT (below 0.4) can reduce the light in a room by half or more, while a high VT (above 0.60) can cause glare. Large windows can also have undesirable effects.
- Clerestory Windows
Clerestory windows are high, vertically placed windows that can increase direct solar gain when oriented towards the equator. When facing the sun, clerestories and other windows may admit unacceptable glare.
In a passive solar house, clerestories can provide direct light to polar-side rooms and diffuse light to spaces like classrooms or offices. Clerestory windows also shine onto interior walls painted white or light color to reflect indirect light to interior areas, reducing shadows.
- Sawtooth Roof
A sawtooth roof is a roof-angled glass alternative found on older factories. It has vertical roof glass facing away from the equator side to capture diffused light, while the angled portion of the glass-support structure is opaque and well insulated.
The sawtooth roof partially reduces the summer “solar furnace” skylight problem, but still allows warm interior air to rise and touch the exterior roof glass in the winter, causing significant heat transfer.
Skylights are light-transmitting fixtures that fill openings in a building’s roof. They are widely used in residential and commercial buildings as they are the most effective source of daylight on a unit area basis.
An alternative to a skylight is a roof lantern, a daylighting cupola above the roof, typically made of wood or metal with multiple glazed glass panels.
A laylight is a glazed panel set flush with the ceiling to admit natural or artificial light. They typically use stained glass or lenses in their glazing, but can also use alternative materials such as white muslin in the case of the Lyme Art Association Gallery.
An atrium is a large, open space inside a building that allows for daylight to enter through a glass roof or wall. The main purpose of an atrium is to provide a visual connection to the outside and bring natural light into the central circulation or public area.
However, the amount of daylight that reaches the working spaces can be limited. To ensure balanced daylighting, the amount of light that penetrates the different storeys of rooms surrounding the atrium must be considered.
Light from the sky can easily reach the upper storeys, while the lower storeys rely on light reflected from the atrium’s internal surfaces, such as the floor. If the atrium walls are light in color, they can reflect more light to the lower storeys.
Translucent walls are made of materials that allow some light to pass through. Glass brick walls are traditionally hollow and filled with fine concrete grout, while some modern glass brick walls are solid and filled with transparent glue.
Optical fibers and fiber-optic concrete walls can also make solid concrete walls translucent by transmitting light through them. However, the amount of light transmitted is typically low, around 5%.
These walls are often used outdoors as dividers between two heated spaces or in temperate climates, as they do not provide good insulation. Greenhouse walls are designed to transmit as much light as possible while minimizing heat transfer, and can be made of various transparent or translucent materials.
Benefits Of Daylighting
Daylighting offers numerous benefits, especially in reducing energy consumption in commercial buildings. Electric lighting is a major contributor to energy use, accounting for 35-50% of total energy consumption.
In summer, the heat generated by electric lights can cause overheating, but using daylighting can cut energy used for cooling by 10-20%. In some cases, total energy costs can be reduced by up to one-third through strategic daylighting.
This not only saves money but also reduces greenhouse gas emissions from energy production. Moreover, exposure to sunlight has been shown to improve mood and productivity.
In the workplace, natural light boosts mood and productivity, as it triggers the production of serotonin, a mood-lifting chemical. It can also reduce symptoms of seasonal affective disorder, such as difficulty concentrating, low energy, loss of interest, and moodiness.
Remote Distribution Of Daylighting
Anidolic lighting, also known as remote daylight distribution, is a method of bringing natural light into spaces without windows or skylights. This is achieved through the use of mirrors, prisms, or light tubes that redirect the light into a room.
The human eye’s non-linear response to light means that spreading light to a larger area of a room will make the room appear brighter and more usefully lit.
There are several methods of remote daylight distribution, including light reflectors and shelves, prisms, and light tubes. Light reflectors and shelves were once commonly used in office buildings but have since been replaced by other methods in combination with artificial lighting.
Light shelves are an effective way to enhance the lighting from windows on the equator-facing side of a building. Prisms, which have been used for centuries, can redirect light sideways to light the deeper portions of a room. Daylight redirecting window film is a modern version of glass prism tiles.
Light tubes, also known as tubular daylighting devices (TDDs), are placed into a roof to admit light into a focused area of the interior. TDDs use modern technology to transmit visible light through opaque walls and roofs.
The tube itself is a passive component, consisting of either a simple reflective interior coating or a light conducting fiber optic bundle. It is capped with a transparent roof-mounted dome and terminated with a diffuser assembly that distributes the available light evenly.
The tubular daylighting device was invented by Solatube International in 1986 and was first brought to market in Australia in 1991.
In conclusion, remote daylight distribution systems can provide natural light into spaces without windows or skylights, and can be a useful solution where no other options are available. Despite some losses and inefficiencies, these systems can still be appreciated for their ability to bring light into otherwise dark spaces.