Building Efficiency into Your Building

Carl Cohen

Over the past decade, several key trends are impacting how companies use and manage their physical buildings and office space. Among these trends are energy conservation, cost allocations for multitenant venues, expectations around ubiquitous, secure network access and space optimization. Given the rise in telecommuting and the on-demand access for space to host informal collaboration sessions, these factors must be addressed in near real time. To address all of these factors, there is a growing need for interoperability and connectivity among the various sub-systems found within a commercial building. These include sub-systems internal to building infrastructure such as lighting, temperature, access control and signage. They also include sub-systems deployed within the property but not directly controlled by the building owner such vending equipment and utility meters. Original Equipment Manufacturers (OEMs) and system integrators (SIs) who develop and deploy these building sub-systems can leverage technologies that enable ‘internet of things’ (IoT) functionality to deliver the requirements needed to ensure overall building efficiency. This article will address some key components which enable the interoperability, connectivity and processing associated with efficient building automation.

Managing the Building Environment

avt-201606-avt-article4-img1 When it comes to managing operating costs, the first area building managers look at is electricity of which a significant portion is used for controlling temperature and for lighting. OEMs have developed sensor based systems to help automate usage and most of these systems operate independently of one another. Utilizing an environmental control unit to better integrate the individual sub-systems will enable significantly improved results. In the example below, the unit is driven by a 32-bit microcontroller from Microchip (PIC32MZ family) which has an integrated Floating Point Unit (FPU) for robust calculation and the ability to connect with a wide range of peripheral buses. There is sufficient capability on the device to interact with the various sensor inputs feeding the appliance while concurrently interacting with cloud hosted enablement applications via an IoT gateway. The environmental control unit example also includes a motion co-processor to balance the workload by filtering, compensating and fusing raw sensor data to improve system performance with smoother, faster and accurate orientation data. The Microchip SSC7150 interfaces with the MCU via the standard I2C connection and is compatible with a variety of sensor types including temperature, accelerometers and gyroscopes.

The environmental control unit receives data inputs from conference rooms, offices and common areas, such as the foyer, from a series of sensors deployed throughout the facility. These include temperature and ambient light sensors just to name a few. The Analog Devices ADT75T contains a band gap temperature sensor and 12-bit analog-to-digital converter (ADC) to monitor and digitize the temperature to a resolution of 0.0625°C. This high degree of precision enhances the overall response time of the system which translates to lower energy usage and reduced costs. In addition to the temperature sensor, an ambient light sensor, such as the VEML7700 from Vishay, monitors lighting conditions and quickly triggers when lights should be on or off. The VEML7700 is a high-accuracy ambient light sensor that includes a highly sensitive photo diode, a low noise amplifier, 16-bit A/D converter, and supports the I2C bus communication interface. By analyzing the data from the two sensors concurrently, and leveraging automated instructions delivered to the environmental control unit via edge analytics, both the lighting and temperature are managed intelligently to reduce the overall cost of operation. For example, when the sensors indicate the room is empty, the temperature is turned up and the lights are turned off simultaneously. To realize even further energy efficiency gains, the lighting fixture can incorporate the Vishay VLSL12A03 high-brightness LED module. This module combines high lumen output with excellent heat dissipation to drive optimal performance. It includes 12 LEDs connected in series with a maximum current per LED of 1.5 A. The overall the power consumption of the module is only 36 W at Tsp = 85 °C.

When it comes to managing operating costs, the first area building managers look at is electricity of which a significant portion is used for controlling temperature and for lighting.

When temperature conditions require adjustment, based on sensor data analysis, the environmental control unit can interface with the HVAC controller. The HVAC unit will in turn start or stop the fan motor, adjust the motor’s speed or send a signal to adjust the vent angles in the zone associated with the temperature sensor. To drive the motor efficiently, while protecting the system from a high voltage short circuit IGBT operation, an isolated gate driver is recommended. The ADuM4135 from Analog Devices is a desaturation detection circuit that contains noise reducing features such as a 300 ns masking time after a switching event to mask voltage spikes due to initial turn-on.

The environmental control unit also controls motors in the effected zone to adjust the vent settings. To ensure precise positioning an accelerometer is placed on each of the vanes in the air vent. The Analog Devices ADXL345 is a small, thin, low power, 3-axis accelerometer with high resolution (13-bit) measurement at up to ±16 g. Digital output data is accessible through either a SPI (3- or 4-wire) or I2C digital interface. The ADXL345 measures the static acceleration of gravity in tilt-sensing applications, as well as dynamic acceleration resulting from motion. Its high resolution (4 mg/LSB) enables measurement of inclination changes less than 1.0°. The combination of size and precision allows for exact positioning which optimizes air flow and ultimately helps in lowering energy costs. During emergency situations when power to the building is lost, the environmental control unit can also process instructions delivered from the IoT gateway to activate battery back-up power in sub-systems like access control. The vPolyTan™ surface-mount polymer tantalum molded chip capacitors from Vishay are optimized for power management, battery decoupling and energy storage in industrial applications such as building access control. The polymer cathodes deliver ultra-low ESR for reduced losses and improved ripple current handling. This is an effective way to deal with emergency conditions without overly taxing the rest of the system.

Managing Diverse Communication Protocols

A critical consideration for ensuring interoperability between the individual building automation sub-systems is the selection of core processing components capable of interfacing with multiple communications protocols. The associated level of complexity rises when deploying the sub-systems using wireless technology. Fortunately, this is feasible based on available wireless modules that can interface to the system using standard bus interfaces such as I2C and SPI. At the heart of the building automation example described in this article is the PIC32MZ 32-bit processor from Microchip. In addition to supporting the I2C there are interfaces for high-speed USB, CAN, Ethernet and also SPI. As a result, the environmental control unit can manage signals from an ISM band transceiver, a Wi-Fi module and a Bluetooth™ Low-Energy (BLE) module. As the signal is brought into the unit, the data is introduced to the processor via the standard bus interface, processed and then the output goes out via the appropriate signal connections.

To complement the processor in the environmental control unit, the RN1810 Wi-Fi module is incorporated. The RN1810 is an ultra-low power, 2.4 GHz IEEE 802.11b/g/n surface mount module. This small form factor module is a complete Wi-Fi solution with on-board TCP/IP networking stack, integrated PCB trace antenna, cryptographic accelerator, power management subsystem, real-time clock, 2.4 GHz transceiver and RF power amplifier. The RN1810 is fully-certified, freeing the designer from RF and antenna design regulatory compliance testing, which provides faster time to market.

An example of using an ISM transceiver communication with the environmental control unit can be seen in the HVAC control unit. The Analog Devices ADF7024 is an ultralow power, integrated transceiver for use in the license-free ISM bands at 433 MHz, 868 MHz and 915 MHz. The ADF7024 is suitable for operation under the European ETSI EN300-220 regulation, the North American FCC Part 15 regulation and other similar regulatory standards. The ADF7024 operates under a number of predefined radio profiles. For each radio profile, optimized register settings are provided that cover common data rate and modulation options. There are six radio profiles in total.

avt-201606-avt-article4-img2Bluetooth Low-Energy communications are used in the access control unit within the overall system layout. The BLE module, Microchip’s RN4870 Bluetooth 4.2 Low-Energy module is designed for easy implementation by eliminating the need for RF signal design expertise. Developers can easily interface to the device via a standard UART interface. The RN4870 has a completely integrated Bluetooth software stack, and offers a shielded regulatory certified version with built-in antenna. In this application, the BLE module is used in the access control unit primarily to interface with the IoT gateway to manage credentials. As mentioned earlier, it also connects to the environmental control unit in the case of a power outage to trigger the use of energy stored in the polymer capacitor.

In some cases, appliances are deployed in the building but are managed by a third party. Often, the appliance requires connectivity but is prohibited from accessing the building network. Examples include vending machines, automated teller machines and utility meters. To address these situations, OEMs can leverage cellular routers embedded directly in their appliance. The MultiConnect® rCell 100 Series of cellular routers offer a robust Ethernet or serial network interface platform ready to deploy. The intuitive user interface and free cloud device management allows for quick configuration and over-the-air upgrades. Enhanced with features such as WAN Failover and Certificate Management, the MultiConnect rCell 100 Series creates an ideal environment for secure and redundant communications critical to the reliability of remote monitoring systems. These routers support 4G-LTE, 3G and 2G cellular technology and are PTCRB certified and verified for use on the major carrier’s networks.

To meet the demands for extended IoT connectivity, Avnet has aligned with Aeris, a leading provider of complete IoT and M2M network solutions as one option to provide cellular data services and management across a wide range of coverage models. Through Aeris, Avnet supports multiple cellular technologies such as CDMA, GSM and LTE across more than 500 carriers in over 180 countries. This strategic relationship provides an Avnet- branded industry leading connectivity management platform. This platform provides real time control and management for IoT deployments with easy single pane views for monitoring and controlling networks and devices, providing added value to businesses by reducing TCO, surprise billing due to overages and engineering and support cycle times. Our wireless data services are available as “capped” or custom plans, sized to customers’ unique requirements, and can be designed in to customer solutions or as an Avnet hardware and software turnkey solution for convenient and ready deployment. Avnet has developed a bundled program including both the cellular modem and a data plan. Contact your local sales executive for more details on how to get started.

avt-201606-avt-article4-img3Building a Bridge to the Cloud

All of the system and sub-system functions described so far work well in a single, closed environment. To achieve true efficiency, these systems must take advantage of cloud hosted applications to enable remote management, monitoring, access to extended data bases, data archiving, provisioning and data visualization to name a few. The means of accessing the cloud in this example is the Dell Edge Gateway 5000. This purpose-built gateway emphasizes security which is critical to protecting the building network from attacks by featuring secure boot and BIOS-level control. The system’s edge analytics capabilities improve overall system performance by executing the majority of analytics function within the gateway saving calls across the internet and reducing the risk of having data compromised while in transit. Additionally the IoT gateway is also able to be the conduit for intelligently managing other building automation systems such as digital signage, irrigation and elements of security for remote monitoring. For example, ensuring the sprinkler system doesn’t run during or immediately after a rain storm. Finally, the integrated edge based analytics can be used to monitor the health of the various sub-systems in the building. Addressing potential infrastructure problems before they occur is a tremendous boost to both productivity and profitability.

The ability to monitor the health of the infrastructure and use predictive analytics for preventative maintenance, along with implementing the means of using automation to drive down energy costs are just two of the direct benefits IoT brings to building automation..

Leveraging the gateway also opens up new business models for building management companies running multitenant facilities. Services such as automated, consumption based billing for conference rooms and other physical resources are possible. Additionally, value added offerings can be introduced such as enhanced security services to protect sensitive areas such as a lab or design space or virtual administrative support through remote, connected resources.

Taking Building Efficiency to the Next Level

This article has explored the internal and external functional elements associated with facilitating building automation in a smart, connected and cost effective manner. Through interoperability across sub-systems, support for multi-faceted communications protocols operating concurrently and linkage to cloud hosted enablement applications, OEMs and SIs can capitalize on the growth potential associated with the advancement of building automation. The ability to monitor the health of the infrastructure and use predictive analytics for preventative maintenance, along with implementing the means of using automation to drive down energy costs are just two of the direct benefits IoT brings to building automation. New business models enabled through this connected system of systems further enhances profits, customer loyalty and differentiation in the competitive commercial real estate market. Talk to your Avnet sales executive to learn more about the products mentioned in this article along with the balances of the technologies and services available to help you reach your objectives faster.