Incorporate lighting controls with BAS to save energy
Energy efficiency and LEED
LEED 2009 New Construction (NC) rewards the use of daylighting and controls. Incorporating both of these strategies contributes to energy savings and can help achieve several perquisites and credits in LEED 2009 NC:
- Sustainable Sites (SS) Credit 8: Light Pollution Reduction. A lighting controller can turn off lighting in a building between 11 p.m. and 5 a.m. Also, a controller could provide shielding of interior lighting through the use of automatic shades between 11 p.m. and 5 a.m.
- Energy and Atmosphere (EA) Prerequisite 1: Fundamental Commissioning of the Building Energy Systems. Commissioning of the lighting and daylight harvesting controls is a requirement to achieve this prerequisite.
- EA Prerequisite 2: Minimum Energy Performance. Lighting controls and daylight harvesting can reduce the amount of energy used in a building compared to a baseline system that only meets the energy code.
- EA Credit 1: Optimize Energy Performance. This credit is related to the EA Prerequisite 2 and awards 1 to 19 credits based upon projected energy reduction.
- EA Credit 3: Enhanced Commissioning. This requires a review of building operations including lighting and daylighting controls 10 months after substantial construction project completion.
- Indoor Environmental Quality (IEQ) Credit 6.1: Controllability of Systems – Lighting. This credit relates to providing individual lighting controls to a minimum of 90% of the building occupants or groups in multi-occupancy spaces.
- IEQ Credit 8.1: Daylight and Views. An Enhanced Performance credit also exists for this credit. See the LEED 2009 BD+C Reference Guide for additional details.
Version 4 is the next iteration of LEED. The USGBC announced that LEED v4 would be required for all projects registered after June 1, 2015. Projects registered before June 1, 2015, would be allowed to register for either LEED v4 or LEED 2009.
The current version of LEED (2009) uses ASHRAE Standard 90.1-2007 as the baseline for building energy performance. LEED v4 will use Standard 90.1-2010 as the baseline.
Some lighting power densities (LPD) have been changed, and lighting controls are a major focus in the 90.1-2010 Standard. The goal is to design buildings that are 30% more efficient than those designed using Standard 90.1-2004. Lighting controls present a large opportunity to save energy.
Enhanced Commissioning, EA Credit 1, with LEED v4 proposes 3 credits (compared to 2 credits with LEED 2009) for enhanced commissioning. An opportunity to achieve an additional credit includes developing an action plan for identifying and correcting operational errors and deficiencies, training to prevent errors, and planning for repairs needed to maintain performance.
LEED v4 proposes EA Credit 3, Advanced Energy Metering. This includes installation of advanced meters that can collect and store hourly, daily, monthly, and annual energy usage data using a BAS or comparable system.
A proposed EA Credit 4, Demand Response, is included with LEED v4. This provides a potential of 1 to 2 credits for installation of a load shedding system based upon the availability of a demand response program. The goal of this credit is to provide more efficient energy generation and distribution systems and to increase grid reliability as well as lowering greenhouse gas emissions.
EA Credit 6, Interior Lighting, for LEED v4 proposes to modify the LEED 2009 credit by providing at least three lighting levels or scenes (on, off, or midlevel). Midlevel is 30% to 70% of the maximum illumination level not including daylighting.
Manual or automatic glare-control devices for all regularly occupied spaces are proposed to be a requirement with EQ Credit 7, Daylight Credit in LEED v4. A potential of 3 points is proposed with LEED v4 New Construction.
ASHRAE 90.1-2010 incorporates several daylighting requirements. Daylight harvesting is required when sufficient daylight exists. There are specific daylighting criteria that require daylighting controls based on whether a space in question (non-retail) has primary sidelighting area of 250 sq ft or greater.
The photocontrol sensor with the sidelighting shall be capable of at least one control step of 50% to 70% of lighting power as well as another control step of 0% to 35% lighting power. Adjustments to calibrate the light sensor shall be readily accessible and remote from the light sensor location.
There are exceptions to the sidelighting controls. See Standard 90.1-2010 for more information.
Standard 90.1-2010 includes a new requirement for skylights to be installed in buildings. A minimum skylight fenestration area has been established for certain defined enclosed space types in buildings that are four stories or less and at least 5000 sq ft. Lighting controls are required with toplighting.
If the sum of the daylight area under skylights and the daylight area under rooftop monitors is 900 sq ft or greater, then the general lighting in that area shall be controlled by multilevel photocontrol. The same requirements for control steps for sidelighting exist for toplighting.
Standard 90.1-2010 also requires automatic lighting shutoff in buildings. A lighting controller’s time clock can be used to turn off lighting based upon time of day. For example, during weeknights at 6 p.m., a lighting controller can be programmed to turn off the lighting in a building.
Another requirement of Standard 90.1-2010 is the installation of at least one control device (e.g., light switch, dimmer, or occupancy sensor) for each space enclosed by ceiling-height partitions to control that space’s general lighting. At least one control step of 30% to 70% of the full lighting power is required.
Commissioning of lighting controls is a requirement within ASHRAE 90.1-2010 because it is critical that lighting controls work properly to achieve the anticipated energy savings.
The Illuminating Engineering Society (IES) has a publication, DG-29-11 The Commissioning Process Applied to Lighting and Control Systems, that provides the technical requirements for commissioning. It includes procedures, methods, and documentation requirements for commissioning lighting and control systems.
For more information on Standard 90.1-2010, refer to the 90.1-2010 definitions and the “Know the latest lighting code” article in the August 2011 issue of Consulting-Specifying Engineer magazine.
A successful BAS design that incorporates daylighting and lighting controls will help meet energy codes, help achieve LEED prerequisites and credits, save energy while maintaining appropriate lighting levels for the building occupants, and provide the facility manager with a system to collect and analyze data relating to lighting energy usage. The designer should advise the facility’s owner of the added design and implementation costs of the system against the calculated energy savings and return on investment.
Michael Chow is the founder and owner of Metro CD Engineering. He holds a BSEE from Ohio Northern University and is a member of the Consulting-Specifying Engineer editorial advisory board and a 2009 40 Under 40 winner. Julia Noschang is a mechanical engineer at Metro CD Engineering. She holds a BSME from Ohio Northern University. Noschang is involved with the Programs and Education Committee and the Emerging Professionals Group within the USGBC Central Ohio Chapter as well as the Young Engineers in ASHRAE in Columbus, Ohio.