In general, the lights in the building operate shorter hours than most buildings, but they still operate longer than necessary. There are occupancy sensors located on the fourth floor and in washrooms throughout the building.
There are also large perimeter areas with windows letting in natural daylight for much of each day. Artificial lighting near the windows remains on throughout a typical day, regardless of the amount of natural light, and at times it adds very little to the level of lighting at the work surfaces.
We recommend installing a central lighting control system, incorporating several technologies, to:
|•||Take advantage of daylighting, dimming or shutting off perimeter lights when natural light is available and adequate.|
|•||Provide flexibility in controlling light levels at each office and workstation, through a simple PC software interface, allowing occupants to reduce glare from computer screens and attain a comfortable lighting level.|
|•||Turn off lights based on occupancy sensing, where appropriate.|
|•||Schedule zones, rooms, or even individual light fixtures independently.|
|•||Change the configuration of zones and schedules any time, without changing hardware.|
An extensive lighting control system such as DALI (Fifth Light Technologies) incorporates personal lighting control, occupancy control, time scheduling, daylight harvesting, and variable load shedding to improve lighting and provide aggressive energy savings. Software flexibility allows building operators to control lighting to actual need, rather than the greatest anticipated need, and to adapt easily to occupancy changes.
This opportunity includes installation of dimmable ballasts in the existing fluorescent fixtures, along with a communication module that will allow each fixture to be addressed individually on a local area network.
There is also potential income from demand response (DR) programs. The Ontario government, through the Ontario Power Authority (OPA), has created a DR plan for managing peak loads. Signing up to a DR program through a load aggregator (one example is Energent Inc.) can result in significant savings.
During peak load times, the load aggregator detects demand response opportunities and notifies its customers electronically. The customer then chooses to participate and provides an indication of their curtailment intent (i.e. their load reduction in kW). At the end of each month, Energent pays its customers for their participation. In turn, the OPA pays the load aggregator for administering the pool of participants.
Issues and Concerns
This opportunity generally has a long payback due to having to replace existing ballasts with dimmable (Encelium system) or DALI (Fifth Light system) ballasts. This retrofit makes the most sense when the lights are on for long hours and it is necessary to upgrade the existing ballasts.
Dimmable ballasts are more temperamental than standard ballasts, and can cause some problems. For example, at 166 Frederick St., the building has a poor grounding system that became evident when we installed Philips Mark VII 0-10V dimming ballasts. Many fixtures experienced baffling problems such as striping.
A 2007 National Research Council study in a deep-plan office building assessed energy savings from the use of luminaires using integral occupancy sensors, light sensors (daylight harvesting), and individual dimming control adjusted by office occupants using sliding panels on their computer screens. Data were collected from 86 workstations over a year to examine the energy savings and power reduction attributable to the controls, and how the controls were used. Occupants were encouraged to use the individual lighting control feature by means of e-mail reminders. Energy savings and peak power reductions were determined by comparison to a conventional fluorescent lighting system installed on a neighbouring floor.
The lighting system with multiple controls used considerably less energy than a conventional, ceiling-recessed, parabolic louvered lighting system, achieving overall savings of 69% compared to the conventional system. Two-thirds of these savings were due to the lower power density (the electric power used for a given area) of the installed system, and one-third was attributable to the controls. Furthermore, the energy savings were directly related to concomitant reductions in the daily peak power demand for lighting. The daily average effective lighting power density was only 3 W/m2.
The researchers also determined what the energy savings would have been if only one type of control had been installed. The data indicated, that if used on their own, the occupancy sensors would have saved about 35% compared to the lights used at full power, while the light sensors would have saved about 20%. Savings from the individual dimming controls alone were only about 10%, and their frequency of use averaged only 0.02 user actions per workstation per day. Nevertheless, the study confirmed that the ability of occupants to choose their preferred lighting level is an important benefit not offered by the other two types of control. Occupant surveys, conducted as part of the study, indicated that the lighting system with multiple controls was associated with an indoor environment of superior quality when compared to the conventional lighting system.
Calculations for Encelium Technologies system:
Rough Savings Estimates (For Budget Purposes Only): Average Savings - $0.35 to $1.00 /ft2.
Detailed Savings Calculations: Use Encelium Lighting Controls spreadsheet template.
Rough Costing Estimates (For Budget Purposes Only): New Construction Costs - $1.00 to $1.75 /ft2.
Incremental Cost (excluding costs of conventional controls and standard electronic ballasts) - $0.50 to $1.00 /ft2.
Detailed Costing Calculations: Use Encelium Lighting Controls spreadsheet template.