Daylighting

Topics

• What is daylighting?• Daylighting zones• What do the codes say?• Daylighting controls• What do we need to show on our plans?

What is Daylighting?

• Daylighting is the controlled admission of natural light into a building to reduce electric lighting and save energy.

• Achieved with the use daylight apertures such as skylights and windows.

• Must be coupled with a daylight-responsive lighting control system to reduce lighting and save energy.

Daylighting Zones

• A daylight zone is the floor area substantially illuminated by daylight (ASHRAE 90.1-2010).

• 3 Types:1. Primary sidelighting - windows

2. Secondary sidelighting

3. Toplighting– skylights, clerestories, roof monitors, clerestory roof monitors

• Each code/standard establishes these daylight zones differently.

Primary Sidelighting Code Requirements

Primary Sidelighting Zone Calculation

Secondary Sidelighting Zone Calculation

Toplighting Fenestration Types

Toplighting Code Requirements

Toplighting Zone Calculation

Daylighting Controls Code Requirements

• IECC 2006 does not require any daylighting zones.• IECC 2009/2012 requires all lighting in a daylighting

zone to be on a separately controlled. Manual controls are acceptable (switch or contactor/relay).

• IECC 2012 requires automatic daylighting controls in buildings with greater than 30% wall to window ratio or under skylights.

• Title 24 & ASHRAE 90.1-2010 require automatic daylighting controls (can dim lights or turn off completely).

Manual Daylighting Controls

• System consists of:1. Separate circuit for all lighting within the daylighting zones.

2. Wall switch or dimmer.

3. Lighting control panel, contactors, etc.

Automatic Daylighting Controls

• System consists of:1. A ceiling, wall, or fixture mounted photosensor to measure the

amount of illumination in the daylighting zone. The photosensor sends a signal when a light threshold is reached.

2. A control unit (dimmable ballast or low voltage relay) that receives the signal from the photosensor and issues a command to adjust the lighting appropriately.

3. Dimming or switching controls that receive the command from the controller and adjusts the lighting by dimming it or switching it off.

Automatic Daylighting Control System

Daylighting Controls

What should we show on plan?

• All lights within the daylighting zone circuited separately.• If code requires manual controls only:

1. A dedicated wall switch or dimmer

2. A separate contactor/relay in the lighting control system.

• If code requires automatic controls:1. Photosensor location

2. Controller location

3. Dimmable ballast for fixtures (if required)

Conclusion

1. Determine if daylighting is required for the project.

2. Use the proper code to determine daylighting requirements.

3. Identify daylighting zones.

4. Circuit lighting properly.

5. Indicate code required daylighting controls on lighting plan.

6. Specify dimmable ballasts if required.

Questions?