Best practices for HVAC and lighting controls integration
Understand how lighting systems can be integrated with HVAC systems.
Learn about the codes and standards, such as ASHRAE 90.1, that help define energy efficiency standards.
Know how to integrate controls to ensure all systems integrate effectively.
For decades, the design industry has looked at lighting as the “low-hanging fruit” of improving a building’s energy usage. In 2005, the U.S. Department of Energy reported that lighting energy accounted for more than 25% of all commercial-building energy consumption. Since then, there’s been an evolution in lighting technologies, from compact fluorescent lamps (CFL) and high-performance T8 technology to LEDs coupled with advances in optics, materials, and fixture design. These advances have allowed simple and cost-effective lighting fixture changes that result in lower energy expenditures and large incentives from utility rebate programs. These vast improvements have lowered the energy usage of lighting by more than 25% in 2005 to 11%, as reported by the U.S. Energy Information Administration in 2016. Now that LED technology and advanced lighting controls are more prevalent, it is likely that there will be even more reductions.
As lighting technologies have changed, HVAC systems and their controls have also continued to advance. Electronically commutated motors (ECMs), variable-speed compressors, and more widespread use of advanced control technologies continue to reduce energy usage. While lighting and HVAC technologies have individually progressed, integrating their controls has not been widely accepted and implemented for construction projects. HVAC and lighting control manufacturers have each developed their own solutions to solve their clients’ problems, while building owners are reluctant to have a single source of responsibility for these functions. This article shares best practices, future possibilities, and a case study that demonstrates success and lessons learned when integrating lighting and HVAC controls.
ASHRAE 90.1 and system integration
One of the more common energy standards adopted as code in the United States is the 2013 version of ASHRAE Standard 90.1: Energy Standard for Buildings Except Low-Rise Residential Buildings. This standard outlines several prescriptive strategies for lighting control that must be implemented based on space type. For a majority of commercial building installations, in addition to manual control for lighting, several other automated measures must be implemented. Depending on the space type, these measures may include occupancy/vacancy, daylighting, and auto-off or scheduled lighting control strategies. These “mandatory provisions” are spelled out in Section 18.104.22.168 of ASHRAE 90.1. To accomplish these prescriptive requirements, there are usually several devices required to enable these control functions to be carried out.
ASHRAE 90.1 similarly lays out recommendations that can automatically shut down HVAC systems in an effort to conserve energy. Section 22.214.171.124.1 calls out several strategies to accomplish this, which include scheduling, occupancy sensors, manually operated timers, or an interlock to the security system that shuts down the HVAC system when the security system is activated. These strategies have their place and do not apply to every space type, especially those where shutting down the HVAC system could potentially cause harm to building occupants (e.g., in a laboratory or hospital isolation room).
Even before codes required lighting and HVAC controls, savvy engineers recognized the opportunity for owners to save energy and material costs by using shared sensors to perform multiple building system functions. The most common form of lighting and HVAC controls integration is to select a room-occupancy sensor for the lighting controls that has an auxiliary low-voltage contact. The contact is wired to the HVAC control system and may turn a fan coil or heat pump on/off, turn down a variable air volume box, or be used to reset room-temperature or airflow-control setpoints. ASHRAE Standard 62.1-2016: Ventilation for Acceptable Indoor Air Quality will allow for certain space types to reduce ventilation airflow to zero when the space is unoccupied, according to Table 126.96.36.199, Minimum Ventilation Rates in Breathing Zone, in ASHRAE 62.1. As this new version of the standard becomes more widely adopted, further energy savings can be realized. Combining lighting and HVAC controls in this manner is relatively easy to implement in most commercial buildings, especially where populations tend to be transient. For example, occupied conference rooms cause lower office occupancy rates. Empty spaces, like the offices, do not need lights on and HVAC systems maintaining peak occupancy conditions. Some versions of the code take this optimization to very granular levels—requiring that systems also be wired to control switched receptacles in the rooms to make sure other powered devices aren’t using energy when the room is unoccupied. (See case study for more strategies).
Taking this basic level of integration a step further, these strategies can also be applied in settings with a different intent: enhancing safety. For instance, in operating rooms, ASHRAE Standard 170-2013: Ventilation of Health Care Facilities, paragraph 7.1.a.3, allows the following:
“For spaces that require a positive or negative pressure relationship, the number of air changes can be reduced when the space is unoccupied, provided that the required pressure relationship to adjoining spaces is maintained while the space is unoccupied and that the minimum number of air changes indicated is re-established anytime the space becomes occupied.”
In the case of operating rooms (ORs), air-change rates can typically be reduced from 20 ACH (or more) down to 6 ACH (or less) when the room is not in use, saving a tremendous amount of energy. Historically, the airflow change has been initiated by using time schedules. The same time schedule may also reduce lighting levels within the space. In a typical operating suite, a set number of operating ORs may not be allowed to setback to lower air-change rates or lighting levels so that they are always “ready” for emergency surgical procedures. Alternatively, a nurse manager may need to manually initiate occupied modes for operating rooms during off-hours surgical procedures. Occupancy sensors can simplify this, reinstating the proper minimum air changes and adjusting lighting levels within the space when the space is occupied during the timed unoccupied schedule. Using multiple redundant sensors with proper programming can ensure that occupancy is sensed and avoid any pitfalls of not returning the room to normal duty from unoccupied modes.
Instituting similar strategies in other occupancies, such as laboratories, where high air-change rates are needed for the health and safety of the occupants, but it’s not critical when the spaces are unoccupied. The 2013 version of ASHRAE 90.1, Section 188.8.131.52, indicates that laboratories must follow one of three set criteria, two of which involve reducing air-change rates within spaces. Just like operating rooms, occupancy/vacancy sensors reduce lighting levels and adjust HVAC air-change rates to conserve energy. Designers must proceed with extreme caution when applying these solutions, as the occupants’ environmental health and safety must take precedence over any energy-savings strategies.
While the aforementioned solutions all involve hardwiring an occupancy sensor to the HVAC controls system, more recent projects now take the additional contacts (and additional wiring associated with them) out of the equation. Instead, BACNet or LonWorks open protocols are used over a common communication network to process the occupancy signals. The hard-wired control points that were once directly wired to HVAC equipment controllers now become virtual. As programming, hardware, and protocols continue to mature and become more reliable, this type of approach will become easier and lead to greater benefits from a networked solution.
Benefits of HVAC and lighting integration
So where will this lead us in the future? Well beyond the simple integration of HVAC and lighting. By allowing devices to reside on a networked control system, devices have the ability to communicate with each other, allowing many other possibilities. For example: the implementation of geofencing technology. Geofencing is the use of GPS or radio frequency identification (RFID) technology to create a virtual geographic boundary, enabling software to trigger a response when a mobile device enters or leaves a particular area. This is already readily available in the residential marketplace. A user can setup the system so when they leave the house with their mobile phone, the system will sense that they are outside the fence and complete automations, such as initiate the security system, turn down the heat, and make sure the lights are off. There are other, lesser-known purposes for this type of technology. A surgeon could enter an operating room and the temperature and lighting levels could automatically adjust to his/her liking. When entering a hotel, the RFID tag in room keys could sense an occupant in the building and heading toward a room. The networked control system could turn on lights and adjust the temperature before an occupant even enters. When leaving the room, RFID tagging could be combined with standard occupancy sensors to know that an occupant has left the room, even if a “spare” room key is left behind.
While these benefits provide personal comforts, they can also impact an organization’s bottom line. For example, a warehouse can track the movement of goods and know exactly where certain items are as they move through the facility. Common paths can be tracked, providing real-world data about distances people travel to complete tasks, which could help boost efficiencies in many industries from health care to the factory floor. Shopping centers can understand the travel patterns through stores, and inventory could be moved to higher traffic areas for higher sales volumes. Housekeeping efforts in a large institutional building could improve efficiencies, because if the staff knows where the highest traffic areas are, those areas can be maintained more often, while paths with less traffic may not need as much attention. The possibilities of having a network of sensors throughout a facility are vast, and as the networks and interoperability of systems continue to improve, the adoption of the technology will continue to grow.
Challenges to adopting system integration solutions
With so many potential and added benefits, it may be hard to comprehend why more integrated technologies are not widely implemented. There are many issues that get in the way of widespread adoption, the most common being unfamiliarity. Many engineers and facilities professionals see the systems as overly complex due to unfamiliar products. Design professionals can play an integral role in advancing the future of integration of systems by not running away and, instead, diving into the myriad capabilities of the products being introduced. Successful integration projects need commitment from design and installation teams to follow the original vision through to a final, reliable solution.
An additional hurdle to cross regarding coordinating the controls between lighting, HVAC, and beyond is a fear of commitment and being tied to a single vendor. Even though today’s controls operate on a more open protocol, we find ourselves placing faith in one provider to integrate systems and programming. Controls systems in this industry have yet to reach the level of standardization that information technologies have progressed. The level of commoditized standardization hasn’t evolved to a point that allows seamless integration. Every facility has dealt with this in mechanical systems. Adding lighting controls and other technologies is just the next step in the evolution. As technology continues to standardize, it will become more seamless. Most facilities managers handle commitment issues by having a few trusted control partners at their facility. Coupling this with open-protocol systems results in higher success rates. To prevent being tied to one source vendor, there’s another trend where large institutional facilities are hiring controls engineers who previously worked for them as a vendor and now perform installations, programming, and controls integration at the facility.
Another challenge between HVAC and lighting controls integration is identifying who connects what wire to a device. When construction managers buy out projects, the divisions of labor are frequently drawn between low-voltage control wiring (i.e., less than 120 V) and 120 V or higher voltage-power wiring. It can become more difficult to integrate systems when this type of division happens. For example, one contractor is running the 120 V power for lights or integrated receptacles, but the controlling devices that switches them are 24 V. This results in two electricians, frequently from two different companies, working in the same space on the same system. Having one electrical contractor that has experience working with the mechanical and selected controls contractors can go a long way toward achieving success and avoiding the pitfalls of typical division-of-labor issues.
There is a perception that all of this technology is extraneous, perhaps even considered a luxury. Owners frequently see high levels of investment with a perceived low level of value to them. At a basic level, there is some truth to this. Simple systems have been in place for as long as controls systems have existed. However, as there’s a continued push to increase building performance, devices that freely communicate and work together are needed.
Successful system integration
From the designer’s perspective, for truly integrated control systems for HVAC, lighting, and beyond to come together, it is important to have someone on a project that is dedicated to that function and who can understand the intricacies of each trade. This person needs to own and champion the integration through the design process. Integrated firms that have all services within their walls are in a better position to achieve success; sharing knowledge is simply easier through shared infrastructure or by being in the same room with the right people.
On the construction side, for larger projects it is highly recommended that the controls contractor has their own contract and not act as a subcontractor to a particular vendor. In fact, the chances for success increase if a controls contractor is selected during the design process. The Division 25 controls-integration specifications should require preselection meetings with controls vendors, presenting a detailed approach to the project and informing the selection team of the scope of work. Project-delivery methods, like integrated project delivery (IPD), or other highly collaborative contract arrangements lend well to this type of process.
Maintaining clear and consistent documentation is also crucial to project success. Designers are always asked to create documents to fairly place bids in the marketplace. Bringing the controls vendor on early in the project can help bring clarity to the documentation for the integration process and also save initial investment. Clearer design documents are more easily translated into fabrication drawings by the controls vendor during construction. When the shop drawings are created by the vendor, make sure the designer who is managing the integration pays close attention to the wiring diagrams to make sure the original design’s intent is met.
The commissioning agents for projects will play a significant role in making sure the system functions as designed. Commissioning of mechanical and lighting controls systems is now becoming a code requirement in many jurisdictions due to the adoption of newer energy codes. The adoption of this code requirement will force the follow-through that many times doesn’t occur at the closeout of a project.
Paul Kondrat is an engineering leader in CannonDesign’s Boston office. Throughout his career, he has worked to integrate controls systems in health care, science and tech, and other large institutional projects for more than 2 decades.