October 2011

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HVAC vs. Lighting: the open language we’re really looking for

The scenario of combined (or merged) HVAC and lighting control can be easily achieved .

David Lamarche
Director of Communications,
SCL Elements Inc. / CAN2GO

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The current debate about an open language for building automation systems (BAS), whether based on IEC 61131-3, an expansion of BACnet or another solution is forcing me to underline a much more absurd division within the BAS world: the divide between HVAC and lighting control.

If you look at market data in commercial buildings, there is a ratio of five HVAC BAS for every lighting BAS. This means that scaling from one system to the other is complicated, even though components of both are always occupying the same spaces. Furthermore, looking at the industry’s structure, you’ll notice that many manufacturers and contractors are either specialized in one or the other. They rarely do both; sometimes because of regulatory hurdles, but sometimes because they lack the solution to do it.

Some companies do offer combined solutions, but even there, the two “systems” are far apart. There are controllers and gateways for HVAC, and separate control hardware for lighting, with notoriously costly “system gateways” to bridge everything together. Things should be much simpler considering that in most cases, HVAC and lighting deal with the same basic language of analog and digital inputs and outputs.

A costly mistake
This divide has had a steep cost for system integrators, building owners and facility managers. For owners and managers, the high hardware and software costs of installing each system has pushed them to choose between the two instead of gaining the energy efficiency advantages of both. When parallel systems (non-integrated) are installed, it also increases the time and resources dedicated to manage both.

It would be much more cost-effective for all stakeholders to be able to use a single room or zone controller to handle both HVAC and lighting applications at the same time.

Merging HVAC & lighting control
The scenario of combined (or merged) HVAC and lighting control can be easily achieved by using CAN2GO controllers. Here is a diagram comparing the traditional application-specific BAS architecture to the CAN2GO multi-purpose system architecture:

Architectures Compared
On the left, the traditional architecture requires much more hardware and installation labor (wiring, repair) than the CAN2GO architecture on the right.

Using wired & wireless programmable controllers to merge HVAC and lighting control holds many advantages for buildings owners, facility managers and contractors.

Case study: K-12 school and school board
The St-Joseph school of the Samares school board near Montreal (QC, Canada) is a fitting example of the seamless and cost-effective use of merged HVAC/lighting control. Furthermore, by using the CAN2GO system, the contractor estimated saving 61% on electrical labor and 32% on controller costs compared to his usual building automation system.

Saint-Joseph Elementary School 
The St-Joseph elementary school had no remote or programmable control of its lighting or HVAC. The only thing the school had was central heating without any thermostats in classes or hallways and a typical ballast lighting installation without any zones. Besides adding better in-room and remote programmable control for both heating and lighting, St-Joseph required a system that could push points upstream to the existing BACnet IP system being used by the school board. The school board also had other requirements: no cancelation of classes, no extra charges for installing the system overnight or on weekends and no dust hazards for the children.

CAN2GO controllers were chosen for the project because any single unit could manage thermostats, actuators, relays and light switches at the same time. The control of these end-devices is done via EnOcean wireless communication. The controllers also network wirelessly, via ZigBee mesh. The only wired connections required for the entire installation were to power up the controllers and actuators, and one Ethernet connection to the LAN, to push the BACnet points to the school board’s system.

For the two main floors of the school, about 18,000 square feet, only nine CAN2GO units were needed to control 60 HVAC end-devices (thermostats, actuators) and 116 lighting end-devices (relays, switches).

The new BAS 
On the left, the network architecture going all the way up to the School board. On the right, a close-up look at one of the zones where all the control and networking is wireless.

“Our school board had the opportunity to install the CAN2GO line. It gave us a full BACnet integrated building automation system combining both HVAC and lighting control. All the communication to and from controllers and end-devices is wireless, so the installation process caused no downtime or repair work, an immense advantage over other alternatives. We plan to install CAN2GO in upcoming retrofit projects”, said Michel Morin, Coordinator of Energy Management at the Samares School Board.

Building automation’s missing link
The demand has been growing rapidly for more cost-effective energy management solutions. There is a reason why the penetration rate of building automation systems is half what it should be. In buildings over 100,000 square feet, barely 45% to 50% of buildings have a BAS. In light commercial and mid-market buildings (smaller than 100,000 sq.ft.), it’s a measly 5%. The problem is that traditional BAS – mostly wired and application specific – do not provide the right return on investment and payback period for building owners and facility managers.

Using fully programmable controllers with strong wireless capabilities is one way to provide energy efficiency to commercial buildings at a better price, and without the invasiveness of traditional solutions.

Think of the possibilities: one controller can offer simultaneous wired and wireless control for lighting and HVAC applications, with in-node support for BACnet, IP/Ethernet, CANbus, Modbus, EnOcean and ZigBee. This is not a pipe dream; it’s reality. A ubiquitous open programming language would be nice for our industry. But getting HVAC and lighting to talk to each other and lowering the cost of ownership of BAS through the use of wireless technology is much more urgent.

For more information about CAN2GO, visit us at WEEC in Chicago (booth #404) or at Greenbuild in Toronto (EnOcean Alliance booth # 6336S). www.can2go.com


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