Control Freaks: Wireless Building Management

In the area of automated buildings, many trends—the adoption of open standards, the interconnection of components and systems with the Internet, and the connection of historically disparate systems to name a few—are becoming reality. Legacy building-management systems (BMS) will become obsolete if unable to support the transition to more complex, higher-performing, and more energy-efficient buildings. Integral to this change are the incorporation of technology for the enhancement and better management of building operations and the monitoring of critical aspects of buildings and the feeding of that data into BMS.

When wiring is cost-prohibitive and/or aesthetically undesirable, wireless sensors and actuators are an attractive alternative for improving comfort and reducing energy consumption. Relocation of wireless sensors and thermostats within a space is extremely easy, with limited disruption to occupants and operations.

Going one step further, beyond traditional battery-powered wireless, is the energy-harvesting EnOcean protocol. Supported by more than 350 companies worldwide, EnOcean-enabled solutions are growing in number and scale. Thousands of hotel rooms and residence halls and countless commercial buildings are utilizing wireless energy-harvesting products.

A new gateway, for example, translates incoming EnOcean wireless transmissions into BACnet/IP objects. This cost-effective-yet-robust device works bidirectionally and can communicate with any product that utilizes a standard EnOcean profile. The gateway can listen to any number of sensors, including temperature, humidity, and carbon dioxide, as well as light levels (daylight harvesting).

HVAC Controls Strategy

In hotels, residence halls, and retail and office spaces, the utilization of setbacks has been a common strategy for reducing energy consumption. When air temperature is reduced in heating mode and increased in cooling mode, energy savings of 20 to 40 percent can be realized. Even deeper setbacks, including the turning off of HVAC when a space is determined to be unoccupied, can be implemented. In Hawaii, for example, new hotels are required to have door sensors for lanais that, when triggered open, turn cooling off. This prevents air-conditioning systems from running when balcony doors are open.

Before wireless, nighttime setbacks were deployed using time clocks, with little ability for modification on the fly. With wireless controls, temperature can be monitored accurately and occupancy detected in any space in real time. This information is reported to a BMS instantly so airflow can be balanced across a building. The advent of a simple wireless, battery-free remote temperature sensor allows temperatures across and around a building to be monitored and measured. This is ideal because many thermostats are limited as to where they can be placed and oftentimes do not adequately provide ambient-temperature readings in a room.

Improving Boiler Controls

In much of the Northeast, boilers are utilized for hot-water or steam heating. Many of the buildings served by these boilers are older, and their controls schema is driven by outdoor temperature only. This is acceptable, but surely not ideal, particularly when about 40 percent of the energy used to heat and cool buildings is wasted. Presently, the way to achieve an ambient temperature during heating season is to open a window, which surely is not the most cost-effective way to optimize a building. Thermostatic radiator valves (TRVs) can be installed to allow heat to flow to individual radiators when room temperature is below an adjustable setpoint. While beneficial, TRVs have limitations. One is that the temperature sensor typically is located on the TRV or required to be very close to the dial, which limits the ability to get an ambient reading for an entire space. Another is that there is no way to get information from a TRV back into a boiler control system or BMS.

An innovative product set that is being implemented to control hot-water and steam heating systems consists of a wireless valve actuator utilizing a wireless, self-powered thermostat. The thermostat has a digital screen providing information about indoor temperature. An occupant can turn a dial to a desired setpoint. Information then is communicated wirelessly to the valve actuator, which reduces or increases the amount of hot water or steam flowing through the radiator. The thermostat includes a seven-day programmable feature, which allows the two devices to work together, with no need for a BMS. Where a BMS exists, the thermostat can communicate to the building’s boiler controls, and this information can be used to balance the building. No longer does there need to be a “cool” side and a “warm” side of a building. This type of solution can achieve energy savings of 10 to 25 percent on average.

Integrating Lighting Control

At one time, BMS were unable to take lighting into account. Today, however, integration of traditionally siloed systems is occurring. Information from wireless occupancy sensors is sent to a BMS and used to activate lights and HVAC. Information from wireless light-level sensors, meanwhile, is used to dim luminaires and actuate window blinds. All information provided by wireless sensors can be logged within a BMS, highlighting trends. This information then can drive automated notifications to maintenance workers. This enables building operators not only to react more intelligently, but to predict events and, thus, be more proactive.

Conclusion

Wireless technology is becoming increasingly cost-effective, particularly when total cost of ownership is considered. Wireless, battery-free technology means little to no ongoing maintenance of devices, no disruption to operations, and the ability to install devices and adapt to changing tenant/space needs easily. The advent of gateways means scale no longer is a concern with wireless; the ability to bring valuable information into a BMS utilizing BACnet is available and surprisingly cost-effective. The future of the built environment no longer is a point for debate; it is here and happening.