November 2010
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BACnet In Public Administration Buildings

Lowering Energy Consumption While Maximizing Comfort

Salvatore Cataldi
Salvatore Cataldi

 ESAC

The best way to save money is to keep systems switched off.  We would achieve an unbelievable energy surplus, but who of us can work in an office with stale air, no conditioning and no lighting?

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Talking about the place we work, the goal is always to achieve the best “compromise” between comfort and energy consumption. The process that finds this “compromise” is system controlling.

ESAC, a BACnet System Integrator in Italy http://www.esacsrl.com, together with the Energy Efficiency department of the Polytechnic University of Turin, conducted integrated research to build an automatic system for energy consumption control and optimization. This system was to be installed in office buildings of the Piedmont regional administration in the north-west of Italy. The project, named BComfort, confirmed what different well known companies in the building energy consumption analysis field foretold.

Experimental method: metering, analysis, control

“Simple is better”: this motto is always true. The challenge was to reduce energy consumption in many different buildings keeping a good comfort level. In approaching such a complex problem, it is of great help and a good experimental method, to break down the big one into small and simple problems and then face them in a common, simple way.

If the goal is to reduce energy consumption, then we need to accurately know how much energy our systems consume. Once we’ve got the figures, we need to accurately analyze and deeply understand them, this is important to determine what is convenient to control. Then it is important to operate in a sharp and prompt way.

In the building life-cycle these three steps: metering, analysis and control run continuously one after the other and they change as the building's internal or external situation changes.

BACnet and the integrated metering, analysis and control system

First we set up the experimental method and following the same method; we found BACnet to be the best integration platform. The ISO 16484-5 (BACnet) standard, more than offering real interoperability among devices from different producers, is based on an extremely scalable system design that allows our small and simple solutions to be interconnected in a much more complex system scattered over the region.

ISO 16484-3 standard describes building automation logic functions and BACnet (ISO 16484-5) represents those functionalities under the information technology point of view. ISO 15232 “Energy performance of buildings - Impact of Building Automation, Controls and Building Management” refers to ISO 16484-3 in evaluating energy efficiency of building automation functionalities. In Europe every country is working on the EPBD (Energy Performance of Building Directive, for further reading about EPBD activities in Italy: http://www.buildup.eu/system/files/content/P168_Italy_Impact_compliance_control_ASIEPI_WP3.pdf, http://www.buildup.eu/system/files/P084_EN_Italy_June_2008_p3184.pdf ) and ISO 15232 is an extremely important focus on building energy efficiency evaluation.

It is evident that BACnet can be considered not only as a communication protocol or an integration platform but also as a point of convergence for different systems within the building. So why we should reinvent the wheel?

Testing ground

The research activity lasted for several months covering from winter 2009 to summer 2010. The building had a Daikin VRV air conditioning system with 263 internal units - almost one in each office, a chiller and a small boiler room serving three AHU for a total air inlet of 34000 cubic meters per hour with variable speed drives. This project was conceived in the year 2000, and at that time it was an extremely modern project.  The four systems where designed to be operated under a common graphic interface but were not connected under a logic point of view. Each one had its own schedulers and setpoints.

These four HVAC systems were “BACnet networkable” and so for our research activity a B-OWS, ORCAWeb from Delta Controls, was setup to store collected data in a relational database and to publish on the Internet a web site with consumption details and an integrated control interface.

Optimizing energy savings in relation to comfort level was the goal of our research.

How the comfort level feels to the people working in the building was measured by weekly questionnaires. At the same time the temperature in every single office, and the power and thermal energy consumption for each system component was measured and stored in a relational database.

Data analysis and comparison was made through the B-OWS web interface from where the operator was able to setup a new set of parameters for the coming week.

The three steps of metering, analysis and control were there, and brought us good results.

Energy savings and user satisfaction

Having direct feedback from users working everyday in the building gave us the opportunity to fine tune the system with automatic logic that sees the interaction of outside temperature, building thermic lag and efficient scheduling. User satisfaction was so achieved.

Energy saving goals have been evaluated in terms of savings of electricity consumption. During winter and summer this reduction has been an average of 30% of cost savings compared to the previous operation.

This result is coherent with ISO 15232, that forecast a maximum level of savings of 39% for automation systems within office buildings. At the same time this result is equivalent to what the BOMA (Building Owners and Managers Association) foretells: a potential energy consumption reduction by 30% by means of automation processes similar to the ones implemented in our research.

Verifying systems efficiency

As a follow up to its development, this project will be continuously implemented on the same building but not only for energy consumption reduction. Collecting data for a longer time will be a base for systems efficiency compared analysis during their life-cycle. This is the next goal for this project within the original building; to automatically understand if and when a system is going out of its normal operation parameter or if there is an efficiency reduction.

This will be implemented not only for electric power consumption but also for natural gas consumption.

Different sites in a single system

Reliable Controls All the concepts and strategies developed during the research period can be applied to all the different buildings of the Piedmont regional administration. There is an IP network connecting all the regional office building in a Wan. A BACnet network has been designed on this IP network infrastructure. On old plants, BACnet freely programmable controllers will be used for data collecting and boiler room control. Modern plants, already with BACnet interfaces, will be directly connected to the network by means of BACnet routers where needed.

Thanks to the BACnet scalable design the whole system will be smooth and the cost of new extensions predictable.

Moreover, having all the sites connected in an single system it will be simpler to develop a performance analysis all over the region, gathering a much richer set of information.

The analysis of this information and the capability of accurate control on every different site, in addition to the advantages described in the BComfort project, will lead to new goals coming from new opportunities for energy savings.

From HVAC to intelligent lighting, the integrated automation system

The HVAC system is the first of the two different kinds of systems demanding the most of the energy consumed by a building, the lighting system is the second.

Within the same building as the BComfort project, a new research activity is about to start to reduce the energy consumption of lighting for every single office while keeping the standards of comfort high.

Implementing motion detection and day-lighting strategies, a system with an integrated web services based dashboard will be in the hands of the facility manager. This new system will be implemented on the same network infrastructure built for the BComfort project.

Through this interface it will be possible to set up lighting behaviours for each single office. Important energy savings are again predictable.

The next step will be the integration of different systems such as air conditioning and lighting, to fully exploit interoperability by implementing different comfort scenarios (out of service, stand-by, comfort) controlling temperatures, and lighting according to the actual occupancy of the office.

What next?

We discovered that implementing an open standard such as BACnet at every automation level, from the meter to the operator dashboard, gave us an enormous capability for data collecting, analysis and control. In simple words a powerful tool to let us focus on actual independent system optimization. And this is what we’re going to do next.


About the Author

SALVATORE CATALDI,
General Manger at ESAC srl, Torino, Italy - http://www.esacsrl.com

Active member of the WG-T in the BACnet Interest Group Europe, Salvatore has been working since 1995 as a professional consultant for different companies in the development of internet distributed systems for telemetry, multimedia services, process and production control and energy management. Author of several publications on system integration for building automation through open and standard software media, in 2004, with other associated engineers, he founded ESAC company to bring ICT experience to the building automation field. Ever since its foundation, ESAC has been a System Integrator adopting BACnet as the integration platform where every sub-system in the building converges. ESAC, in the last years, started producing gateway solutions, developed for its own BMS first, as independent engineered products. Salvatore can be reached at bacnet@esacsrl.com

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