By Bill Swan
Published in the June 2009 issue of Today’s Facility Manager
While HVAC, security, lighting, and other building automation systems (BAS) continue to evolve separately and become more powerful, work continues towards integrating them into a single, unified BAS. There are factors today that will drive this integration of disparate systems which, from the perspective of a facility manager (fm), may require more work, but there are also significant benefits to be realized.
The Need For Efficiency
Foremost among the drivers for integration will be energy pricing. Although prices have fallen from last years’ highs, and despite recent natural gas discoveries that could more than double known North American reserves, when the world’s economies come back, there will an increasing demand for fossil fuels—which will eventually push prices upward. Meanwhile, significant additional contribution from renewable energy sources, in particular wind and solar, is a long way off due to transmission, storage, and political issues.
Add to this the efforts to reduce carbon dioxide emissions (which have already blocked construction of a number of coal fired plants), the resistance against nuclear power, and experience elsewhere with cap and trade schemes (which raised German wholesale electric rates up to 60%), and it’s clear energy prices are going to rise significantly. The buildings managed by fms are going to have to become more efficient in their use of energy.
But it is not only energy prices that will exert pressure for more efficient buildings. “Building labeling” programs will be coming to the North American market soon. Such programs are already in operation in Europe under the Energy Performance of Buildings Directive approved in 2002. Under this system, the performance of a building is calculated and rated to verify that it meets minimum requirements. An energy performance certificate is created or updated when a building is constructed, sold, or rented out (with regular inspections). Current residential labels for the UK appear in Figure 1, and it is surmised the final commercial label will at the least contain the graphic elements.
ASHRAE is also developing a Building Energy Labeling Program with a focus on Asset (design) and Operational (measured) ratings. The program is scheduled to be released this summer. These certificates may be required by code to be prominently displayed, similar to restaurant cleanliness certificates. This will put pressure on fms to keep certified buildings running efficiently.
Standards Lead The Way
The energy efficiency of commercial buildings today leaves room for improvement. The most recent Department of Energy (DOE) Commercial Buildings Energy Consumption Survey showed that a significant amount of commercial building floor space is not served by even the most basic energy strategies (such as setting back thermostats during scheduled non-occupancy).
The oil crunch of the 1970s resulted in the development of ASHRAE Standard 90-1975, whose goal was to reduce the energy use of buildings by 40%. As new techniques for saving energy were developed and incorporated, that standard has been revised and republished, most recently as ASHRAE Standard 90.1-2007, Energy Standard for Buildings Except Low-Rise Residential Buildings. This update covers many aspects of the building including its envelope, HVAC system, lighting, and more. Various revisions of 90.1 have become the basis for other standards and guidelines for achieving even greater reductions in energy.
One such standard currently in development is ASHRAE Proposed Standard 189.1P, Standard for the Design of High Performance Green Buildings Except Low-Rise Residential Buildings. A cooperative effort by ASHRAE, the U.S. Green Building Council (USGBC), and the Illuminating Engineering Society of North America, it draws and builds on several ASHRAE standards, in particular 90.1 (energy), 62.1 (indoor air quality), and 55 (thermal comfort), to show how to achieve greater energy efficiency.
Each of the key subject areas of 189.1P, such as “energy efficiency” and “site sustainability,” is comprised of five sections:
- Scope of the subject area;
- Methods of complying with the section;
- Mandatory requirements;
- Additional simple measures; and
- Additional sophisticated measures.
In addition to Standards 90.1 and 189.1P, ASHRAE is developing and publishing its Advanced Energy Design Guides (AEDGs), starting with guides to 30% less energy consumption than the baseline standard 90.1. Guides for small office buildings, small retail buildings, K-12 schools, and warehouses have already been published (with others to come).
Not all the AEDGs are targeted for new construction; an Energy Efficiency Guide for Existing Commercial Buildings is currently in development. Subsequent guides for 50% and 70% reduction in energy use are also planned for release over the next few years.
Finally, building on these standards and guides and feeding back into them are the USGBC’s LEED reference guides for both new construction and existing buildings (the 2009 version of the latter is titled Green Building Operations and Maintenance Reference Guide).
Getting To Integration
Creating a green building starts with an integrated design process that brings together the major issues and key participants, each with their own skills and knowledge. Similarly, to get the most energy efficiency from a BAS, designers must first evaluate how to achieve better efficiencies within the various system and then reach across the boundaries to integrate the systems. The LEED reference guides provide a good starting point for this, whether or not a LEED rating is actually being pursued for a new or existing building.
Lighting consumes about 35% of the electricity used in commercial buildings and can affect the HVAC system through the heat it produces. Lighting can also have effects far beyond the building and its grounds, as observed by the various “dark sky” organizations, wasting energy in the production of light pollution.
For these reasons, the guides may call out the use of daylighting controls (stepped or dimmed lighting near windows), individual controls for some percentage of the building’s occupants, non-emergency lighting dimmed or turned off during non-business hours, and manual on/automatic off lighting controls using occupancy detectors, whether passive infrared (PIR) or ultrasonic.
HVAC systems are another area where more energy can be saved, but too often, the effort isn’t even made. For example, scheduled thermostat set backs is an old strategy, yet it is still not used in roughly a third of U.S. commercial space. Going beyond this, demand controlled ventilation based on carbon dioxide sensors in spaces with highly variable occupancy (instead of setting a fixed airflow rate) avoids the extremes of too much conditioned air in an unoccupied space and too little air when occupancy is high. The LEED guides also specify monitoring ventilation system performance with alarms for possibly energy wasting, out of spec system performance.
Measuring and recording energy consumption are also called out in the guides, although in the LEED rating systems, the number of LEED points that can be earned by metering energy consumption varies greatly from one rating system to another. Energy consumption is monitored not only to verify the building’s performance, but also for early detection and possible isolation of problems. Persistence of energy savings after commissioning can be surprisingly short, sometimes declining steeply in the first year.
The above strategies are all energy savers in themselves, and there are other well known strategies within these systems. But when the HVAC, lighting, and other building systems become integrated into a unified BAS, additional synergies start to become possible with little extra effort. For example, the occupancy detector that automatically shuts off the lights when a zone is unoccupied too long can also set back the HVAC zone. (Or similarly, the manual on light control can signal intended occupancy of the HVAC zone for a time.) Or when the building’s entry alarm is enabled (signaling that the building is unoccupied), the non-emergency lighting can all be dimmed or switched off right away. The approaching elevator can turn on the hallway lighting for the arriving passenger. The strategies are not complex, but they become simpler to implement in an integrated system.
Enabling Tomorrow’s Integration Today
The additional benefits of integration need not be limited to the state of the building and the industry at the time the facility is started up, commissioned, and occupied. With a BAS integrating the different building systems (which may be from different manufacturers), fms are not only able to use a single workstation for monitoring, controlling, and recording data from all of their building systems, but the way is open for them to avail themselves of future cost and energy saving strategies not envisioned or implemented today.
The BAS, which started as an energy management control system (EMCS), has come a long way. And along with the effort to extend the standard protocols to integrate more building elements into a single system, the BAS will return to its roots as an EMCS, a major benefit to all fms pressured to reduce energy consumption of buildings.
Swan, LEED AP, is Buildings Standards Initiatives Leader with Redmond, WA-based Alerton. He also works with standards related to building automation, primarily BACnet and LEED, as Alerton’s representative.
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