May 1, 2012
By Andrew Parker, P.Eng., LC, LEED AP
Ontario has signalled its intent to remain among the energy efficiency leaders in North America for new building construction in adopting American National Standards Institute/American Society of Heating, Refrigerating, and Air-conditioning Engineers/Illuminating Engineering Society of North America (ANSI/ASHRAE/IESNA) 90.1-2010, Energy Standard for Buildings Except Low-rise Residential Buildings.
When the six-year ‘roadmap’ for energy efficiency expired on December 31, 2011—as set out by the Ontario Building Code (OBC) and relative to the dated 1997 Model National Energy Code for Buildings (MNECB)—a new path was laid out for the future. Ontario Regulation 315/11 was made under the Building Code Act to require energy efficiency for large buildings and small non-residential buildings conform to an updated Supplementary Standard SB-10.
This standard requires the energy efficiency of those building types for which a permit has been applied after December 31, 2011, exceed, by at least 25 per cent, the energy efficiency levels attained by conforming to the 1997 MNECB. However, it also provides additional compliance paths to achieve this level of energy efficiency. These paths reference ASHRAE 90.1, which is widely used by the North American building industry. Accordingly, Supplementary Standard SB-10 offers the following new compliance paths:
The latter option is the only one that does not require energy modelling. This prescriptive method of achieving compliance includes more than 40 lighting addenda—as compared to the 2007 version—and has made ASHRAE 90.1-2010 one of the most modern energy efficiency standards available. It has also fundamentally modified its scope beyond just design and construction to energy-efficient operations and maintenance.
Lighting systems will continue to feel downward pressure on power densities, with the general expectation that solid-state light-emitting diode (LED) technology will continue to provide necessary efficacy improvements. However, while power density reductions were imposed both indoors and out, lighting controls are the major focus of extra energy efficiency requirements. In fact, plug load controls are a completely new addition to capture the increased use of task lighting and other plug-in electrical devices.
Lighting power density
There are two approaches to achieve compliance with the interior lighting power limits detailed in ASHRAE 90.1-2010—calculation of total load (measured in Watts per square foot) using either the building area method or the space-by-space method of calculation. These are fairly common practice today with the former being a simplified approach, and the latter providing additional flexibility.
Changes to the building area method lighting power densities (LPDs) have averaged a 16 per cent reduction as the limits for many building types have been lowered, or at least maintained. General advances in lighting technology are expected to make up this difference. Space-by-space LPDs, on the other hand, have been reduced for some areas to account for lighting technology improvements (e.g. retail applications are expected to benefit from improvements in ceramic metal halides [CMHs]), but some are also increased to make corrections to previously set limits.
Lighting designers will feel some relief when designing for higher ceilings and longer perimeter wall applications through a room geometry adjustment. If the space-by-space calculation method is used, a 20 per cent LPD increase is available provided the room cavity ratio exceeds the established threshold for the space type. For example, any corridor narrower than 2.4 m (8 ft) automatically meets this threshold and is afforded the 20 per cent increase in LPD. Additional LPD allowances can also be achieved by implementing lighting control strategies above and beyond mandatory requirements.
Renovations will fall under the scrutiny of LPD calculations more often now that any lighting alterations of more than 10 per cent of the connected lighting load in a space must also comply and meet automatic shutoff requirements. Lamp or ballast retrofit projects are also now included.
Exterior lighting zones
To better control exterior lighting use, a new five-zone power allowance table has replaced the single set of exterior lighting power limits. The zones represent the relative development of the site under consideration; for example, whether the local environment is undeveloped park land or rural area, predominantly residential, or a high-activity commercial district.
Each zone is afforded a base amount of lighting power, then provided an allowance for lighting of various surfaces from parking to entrances to building façades. The zone approach keeps outdoor lighting power in check and appropriate to the surroundings. Some trading of lighting power allowances is permitted as long as the result is below the combined total limit. Notable exceptions include directional signage and advertising lighting, as well as feature lighting for historic buildings and landmarks.
Exterior lighting is impacted by the general increased reliance on controls. Automated controls will be required to turn lights off during the day, as is common practice today. However, OBC also mandates some restraint for façade and landscape lighting to be shut off between the latter of midnight or business closing and the earlier of 6 a.m. or business opening. The biggest change requires all other exterior lighting, including advertising signage, to be automatically reduced by at least 30 per cent after hours or when unoccupied. Parking garages, indoor or out, are significantly impacted by this requirement. Dimming technology may prove to be very important in this category.
Indoor lighting controls
Lighting controls play an increasingly important role in reducing wasted electricity indoors. Manual on-switching of bi-level lighting is now the standard to ensure the adequate light level is used only when required. Occupancy sensors are more likely to be referred to as ‘vacancy sensors’ since all automatically controlled lighting must now have manual-on functionality with automatic off-switching. In contrast to the common occupancy activated on- and off-switching, this method provides additional energy savings. In fact, the preference is to automatically switch lighting on to 50 per cent power and manually switch the remaining 50 per cent as this method is proven to generate the greatest energy savings (Figure 1).
As expected, vacancy sensing controls are also now required in more spaces. Currently used in conference and meeting rooms, classrooms, and lunch and break rooms, they will also be required in:
Manufacturers are ready to meet this demand with simple, two-pole, wall-switch sensors or more capable digital lighting management systems that can support more complex requirements (Figure 2).
Vacancy detection systems are now required for room lighting in newly constructed hotels. A control device will be mandatory near the entrance door in new construction projects to control all permanently installed luminaires and switched receptacles. A common approach to error-proofing this process is to employ a device requiring the room keycard be inserted in a slot to activate the lighting circuits. Additionally, a vacancy sensor will be required to automatically turn off lighting in the bathroom within 60 minutes of the occupant leaving the space.
Often an area identified for energy savings, stairway lighting control is one new requirement using the new sequence of operations of lighting controls. All enclosed stairwells must
reduce lighting power by at least 50 per cent within 30 minutes of all occupants leaving the space.
Controls will also benefit lighting designers. As previously mentioned, when additional control methods are employed on top of mandatory requirements, an interior lighting power allowance may be generated to offset lighting loads in other locations. For example, occupancy sensors controlling open-office cubicle lighting fixtures employing continuous dimming operation for personal light level control could provide a 30 per cent interior lighting power allowance bonus. The allowances are calculated as lighting power under control multiplied by the applicable space control factor.
Taking advantage of daylight is mandatory for both ‘primary sidelighted areas’ (i.e. windows) and ‘toplighted areas’ (e.g. skylights and clerestories). When an enclosed space meets the minimum floor area requirement (23 m2 for sidelighted areas and 84 m2 [900 sf] for toplighted areas), lighting automation with three control steps is required:
The ranges allow for daylighting requirements to be accommodated by bi-level switching systems, but this is another example of a good application for continuous dimming systems to provide unobtrusive daylighting control. Allowances are also made for sunlight blocked by adjacent buildings or other structures that can significantly reduce the daylighting opportunity.
To ensure the lighting control system is understood and implemented according to requirements, the goals and conditions must be documented as part of the submittals. Once installed, lighting controls must also be functionally calibrated, programmed, and tested, according to manufacturer’s instructions and new minimum test procedures now provided in the code. Written certification must be provided to verify conformance.
Minimum test procedures include such common items as verifying occupancy sensor placement, sensitivity, and time-outs, as well as confirming low-voltage switches and time schedules are programmed to turn off lighting. Daylight harvesting systems must demonstrate they will reduce lighting power based on available natural light. The tests must not be performed by the individuals involved in the design or construction of the systems, and this responsible party must be stated in the construction documents. Finally, due to the increased complexity, reliance on technology, and proper setup to achieve higher levels of energy efficiency, the code also ensures the owner is provided with all necessary information to understand, use, and maintain the systems.
Expanded scope: receptacle loads
Automatic receptacle control is a completely new requirement added to ASHRAE 90.1, Chapter 8, “Power.” Plug loads have increased to the point of becoming the largest category of electrical energy use, perhaps in part by assuming some task lighting loads as lighting power densities have been squeezed (Figure 3). While not exclusively intended for control of task-lighting plug loads, receptacles can be conveniently tied into lighting time-of-day schedules or by occupancy detection systems to meet the requirement. At least 50 per cent
of all 125-V 15- and 20-amp receptacles in computer classrooms, along with private and open offices (including modular partitions), must now be controlled.
The next generation of standards is expected to continue to push energy efficiency and sustainability by continued expansion of existing control requirements (e.g. adding more light level steps or requiring continuous dimming in certain spaces). Control zone size will be constricted, ultimately to individual fixture control capability. Automated receptacle control will be required in more spaces.
Adding new technologies and techniques provides tools to generate further savings (e.g. control of emergency circuited lighting together with general lighting, while providing a reliable and safe response to emergency situations). Automated reduction of lighting loads at times of peak electrical demand will begin to be a requirement, rather than a feature implemented by certain demand-response programs.
Lighting quality requirements will be considered in parallel with further lighting power density reductions with a goal of also improving overall indoor environmental quality. One example already available is personal lighting control that allows each occupant to select the appropriate light level for their task at hand (Figure 4). Finally, energy monitoring will provide the means to sustain energy efficiency by supplying the tools required to determine how and where energy is being wasted.
The amendment to adopt ASHRAE 90.1-2010 maintains Ontario’s status as a Canadian leader in using its provincial code to regulate energy efficiency in new buildings. Control of lighting energy use plays a vital role toward helping meet the increasing need for energy conservation. To date, no other Canadian jurisdiction has set a building code energy efficiency requirement for large buildings that meets or exceeds MNECB by more than 25 per cent. This amendment to OBC will provide flexibility for designers and builders in meeting the code’s energy efficiency requirements without compromising important objectives related to energy efficiency.
Andrew Parker, P.Eng., LC, LEED AP, is a controls and lighting specialist at Salex/Marnik Inc. With more than 20 years of experience in lighting, electronics, and controls, he is a member of Illuminating Engineering Society of North America (IESNA) and is the communications chair for the Toronto Section. Parker can be reached via e-mail at email@example.com.
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