mwConnect published a case study “Exploring HVAC and Lighting Controls Integration and Interoperability: mwConnect Creates a Demonstration Showcase.” mwConnect, a Bluetooth wireless mesh lighting controls provider, conducted a project in its Sacramento headquarters to explore the integration of lighting control with HVAC systems. The company retrofitted its lighting systems with wireless mesh networked lighting controls (NLC) and integrated them with the facility’s HVAC control to create a showcase for market stakeholders.
The project involved transitioning existing control zones to create defined mesh systems showcasing advanced controls with HVAC integration. The mwConnect offices, covering 10,000 square feet with an additional 15,000 square feet for production and warehousing, housed 30 employees with typical 8 am-5 pm weekday schedules. Before the retrofit, the site used various light sources, including fluorescent, LED, CFL, halogen, and incandescent lighting, along with standalone PIR occupancy sensors and wall switches.
The project team installed 88 lighting fixtures embedded with DALI D4i drivers and D4i wireless sensor controllers and integrated six HVAC units into three identifiable mesh networks, each with its gateway. This setup allowed the team to measure specific issues like drop-off and latency for each mesh network.
Multiple control strategies were implemented, including tunable white, circadian lighting, dimming, high-end trimming, scheduling, daylight harvesting, occupancy/vacancy sensing, and power metering. Signify and Osram DALI D4i drivers were used in the LED luminaires, featuring combinations of single-channel drivers plus wireless controllers and dual-channel tunable white drivers plus wireless controllers. A large conference room was selected to showcase human-centric lighting.
One mesh network, utilizing the mwConnect TruBlu Bluetooth NLC protocol, comprised 44 fixtures in private offices, a break room, a foyer, and open floor plan areas. Each luminaire incorporated wireless mesh sensor-controllers for luminaire-level lighting control. Wireless kinetic wall switches, requiring no wiring or batteries, were also installed in certain offices and common areas. High-end trim (to 70% output) and an occupied dimming level of 55% led to energy savings exceeding 60%. The breakroom featured a 4-button wall switch to facilitate scene control, with four zones created for daylighting plus occupancy and occupancy alone.
A second mesh network, using the Casambi protocol, included 44 fixtures across a large conference room, private offices, an open office area, a library, a server room, a print center, and a transition area to a warehouse production area. The original troffers were replaced with 50W 2×4 LED fixtures and wireless mesh sensor-controllers. In specific spaces, fixture-integrated WCM-200 controllers were deployed instead of sensor-controllers. A 4-button wall controller and dual-channel wireless controller allowed occupants in an engineering office without windows to adjust the tunable white fixtures. The Casambi app’s scheduling features enabled a circadian profile for the large conference room, activating at 6 am with a 2400K CCT and gradually cooling to 6000K CCT through mid-afternoon before ramping back to 2400K until an automatic shutoff at 8 PM. The control scenario also leveraged occupancy sensing and daylight harvesting.
The original HVAC system used zoned Roof Top Units (RTU) and standalone hardwired thermostats. The team replaced all thermostats with wireless mesh-enabled models connected to an edge gateway. The Sequence of Operation was updated from a legacy “Set Point” approach to include data from occupancy sensors. A “cascade” set point program was created, using occupancy data to establish an operating range across an “Occupied/Business hours” and “Occupied/Non-business hours” spectrum with higher heat and lower cool threshold settings, focusing on increasing occupant comfort.
The project used 93 sensor-controllers and controllers, and 17 wall switches, streamlining the communications between luminaires and mesh devices, in addition to the 88 new and retrofitted luminaires.
The project achieved significant energy savings by layering multiple strategies, such as high-end trim plus setting a dim level and leveraging occupancy data to refine the HVAC setpoints. The upgraded systems operated using 2588 watts, a 69% reduction from the legacy lighting’s average of 8280 watts. This resulted in a -45kWh per day reduction and a -11,900 kWh reduction annually.
The total materials cost was less than $24,000, and total project costs, including labor, were just under $39,500. Estimated annual energy savings from lighting retrofits is $1,646. The fixture retrofit, combined with the installation of occupancy sensors, saves 8.3 metric tons of CO2 emissions each year.
The full mwConnect case study can be found here.
Editor’s note: A 24-year simple payback raises serious questions about the approach used in this case study (before rebate and tax credit). I calculate a 13-year simple payback after rebate and tax credit, which is still concerning.
All images: mwConnect.us
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