views

Using Daylighting to Save Energy and Enhance Views

JulieBy Julie Lundin, NCIDQ, LEED AP ID+C, ASID, Director, Emerald Skyline Corporation

My post on the design and progress of our commercial building focused on an overview of what sustainable design is and how it impacts a building’s design and construction and on-going building operations. You can see that post here. A sustainable building utilizes many concepts, solutions and products to incorporate the six fundamental principles of sustainable design:

  • Optimize Site Potential
  • Optimize Energy Use
  • Protect and Conserve Water
  • Optimize Building Space and Material Use
  • Enhance Indoor Environmental Quality (IEQ)
  • Optimize Operational and Maintenance Practices

This post explores the concept of Daylighting and Views, which impacts two areas of the fundamental principles of sustainable design: Optimization of Energy Use and Enhance Indoor Environmental Quality (IEQ).

Daylighting is the ability to maximize or control the use of natural daylight in a building in order to reduce the need for artificial lighting and reduce energy use. Access to daylight inside a building helps create a healthy, comfortable and productive environment for its occupants while reducing as much as one-third of total building energy costs.

Implementing daylighting on a project goes beyond simply listing components to be gathered and installed. Daylighting requires an integrated design approach to be successful. It can involve decisions about the building layout, site, climate, building components such as windows and skylights, lighting controls and lighting design criteria.

The science of daylighting design is not just how to provide enough direct daylight to an occupied space, but how to do so without any undesirable side effects. Beyond adding windows or skylights to a space, it involves carefully balancing heat gain and loss, glare control, and variations in daylight availability.

To implement daylighting into a project it requires systems, technologies and architecture. Below are some of the typical components that are utilized:

  • Daylight-optimized building footprint
  • Climate-responsive window-to-wall area ratio
  • High-performance glazing
  • Daylighting-optimized fenestration design
  • Skylights
  • Tubular daylight devices
  • Solar shading devices
  • Daylight redirection devices
  • Daylight-responsive electric lighting controls
  • Daylight-optimized interior design (furniture, space planning, room surface finishes)

Since daylighting components are normally integrated with the original building design, it may not be possible to consider them for a retrofit project. We are fortunate that the retrofit of our building in Boca Raton lends itself to use daylighting to positively impact two of the fundamental principles of sustainable design. Below are some of the components that our project will utilize:

  • Optimized Building Footprint – Although usually limited to new construction, our building and site enables us to make design decisions that will allow us to create a daylight-optimized footprint. The redesign of our building will maximize south and north exposures, and minimize east and west exposures. Our new façade will face due south which is the optimal orientation for best solar access and ease of control.
  • Climate-Responsive Window-to-Wall Area – With the building sited facing south, we are specifying high-performance glazing (windows). The area is being designed to be a careful balance between admission of daylight and summertime heat gain since our project is located in South Florida.
  • High-Performance Glazing – High performance windows will generally admit more light and less heat than a typical window, allowing for daylighting without negatively impacting the building cooling load in the summer. For our project, being located in South Florida, high performance glazing is very important.
  • Daylighting-Optimized Fenestration Design – An optimized fenestration design will increase the system performance. Windows have two essential functions in a building. 1) Daylight delivery or admittance, and 2) provide a view to the occupants. Daylight admittance requires a window with high visible light transmittance and windows for view need to be clear. Our daylighting fenestration design will be composed of both of these with correct height requirements.
  • Skylights and Tubular Daylight Devices – Both of these devices utilize what is called toplighting, or admitting daylight from above. We are incorporating the use of tubular devices in our building design. These devices employ a highly reflective film on the interior of a tube to channel light from a lens at the roof to a lens at the ceiling plane. They tend to be much smaller than a typical skylight, yet still deliver sufficient daylight for the purpose of dimming the electric lighting. They will be used on the second floor where there will be interior spaces that do not have access to any windows due to our north side zero lot line site.
  • Daylight Redirection Devices – Redirection devices take incoming direct beam sunlight and redirect it. These devices serve two functions: glare control, where the sun is directed away from the eyes of the occupants, and daylight penetration, where sunlight is distributed deeper into a space that would not be allowed otherwise. We will be utilizing both of these methods in our project.   Lightshelves will be used on the south façade of the building, on both floors. The second floor interior will contain clerestory glass components that will distribute light into rooms that have no access to daylight.
  • Electric Lighting Controls - Lighting controls are essential to any daylighting system. No daylighting design will save any energy unless the electric lights are dimmed or turned off when there is sufficient illumination from daylight. If daylighting features such as windows and tubes are not paired with daylight-responsive dimming controls, then the daylighting-enhanced building will likely use more energy, not less, than a comparable building without any daylighting features. Lighting controls consist of continuous dimming or stepped-ballasts in the light fixtures, and photocells to sense the available light or turn off the electric lighting in response. We will incorporate a lighting control system in our building to take full advantage of our daylighting design and the energy savings it will provide.
  • Interior Design – An often-overlooked element in a successful daylighting design is the interior design. The interior design should consider furniture design, placement, and room surface finishes and how they relate to daylight performance. Interior walls may interfere with daylight transmission into a space. The south facing façade of our project, on the first floor will have an open concept so that daylight can penetrate and distribute more fully into the interior space. Walls and ceilings will be as reflective as possible.

To design and implement a daylighting strategy into a project requires a collaborative design process and the daylighting strategies must balance with other project design goals. Access to daylight inside buildings provides a healthier and comfortable environment for its occupants and is also linked to greater productivity. When designed with proper glare control and minimized solar heat gain, daylighting provides high-quality light while reducing energy use for lighting and for cooling.

 

 

http://www.wbdg.org/resources/daylighting.php