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Simply Saving Energy
How small upgrades can yield large returns
Western Allied Mechanical
Energy saving jargon
has become standard among building automation and
mechanical discussions. Everything from ROI (Return of Investment) to
LEED and PV (Photovoltaic) has probably been mentioned in most new
construction projects. But what can you do to save energy in your
building if you have limited capital? What if you don’t have
tens of thousands of dollars to spend on large upgrades with paybacks
extending out beyond ten years? Many building owners and facility
managers aren’t educated on the simpler applications when it comes to
energy retrofits. Simple energy
measures have proved to be extremely effective at reducing consumption
and only require minimal investment from the property owner.
automation is often overlooked as an effective tool to reduce energy
consumption within a facility. Most maintenance personnel turn to
equipment upgrades as well as system design and balancing; all of which
work towards heavy energy reduction at a higher initial investment. PG
& E has looked to curb initial owner expenditures with its energy
payback programs having project compensation peaking at 25-30% in most
retrofits. When considering mid-size facilities and tenant leases
ranging from 5-10 years, PG & E rebates may not be an effective
solution as project returns out last lease contracts. In this case,
simple automation retrofits might prove to be a more beneficial
alternative with the potential of 3-5 year returns.
related energy reduction strategies can be seen in Figure: 1 below.
Included in the chart are requirements, typical project time, tenant
disruption, and expected return for different building automation
energy reduction strategies. For most automation strategies, building
owners can assume minimal tenant disruption during the implementation
of the project as the majority of changes occur programmatically rather
than a physical install. For example, CO2 as part of a DCV strategy
(Demand Control Ventilation) only requires the installation of a CO2
sensor in certain zones. These zones are usually unoccupied spaces that
owners and facility managers can schedule easily for the upgrades. By
specifying networkable zone sensors for DDC upgrades, a contractor
would merely have to wire the new CO2 sensor to the existing room
thermostat in series, thereby minimizing install time.
Figure 1: All
estimates are based on project averages on sites ranging from 30-300k
sq. All sites are different and would require a thorough analysis for proper return estimates.
The simplistic strategies listed in Figure: 1 require little install and rely more on sequence revision within the DDC controls versus having to install additional mechanical equipment. Although sequencing sounds relatively simple with regards to the lack of install, it actually requires a high level of system knowledge to prevent inadequate operation of the controlled equipment. For example, if an air handler currently controls to maintain a duct static of 1.2 inwc and a programmer were to allow it to modulate from that setpoint down to a pressure of .5 inwc, the zones downstream may not be provided enough ventilation; this could be potentially hazardous to the tenant depending on what type of zones are supplied by the air handler. Careful planning and consideration when deploying automation based strategies must be considered to prevent unexpected issues with the different mechanical systems. The most common remedy to prevent failures is to utilize a mechanical design firm to formalize the strategies with a DDC contractor.
Although more expensive, mechanical
firms offer the ability to:
DDC system upgrades to reduce energy often look enticing for property owners and managers due to ease of implementation, although some sites do require mechanical improvements. Among the highest energy consumers in a building are motors utilized mostly for air handler and central plant applications. Reducing the power to these motors through VFDs (Variable Frequency Drives) allows for substantial equipment energy reductions as sequencing is based more upon zone necessity (Demand Controlled Ventilation) rather than assuming full occupancy. Integrating VFDs often requires motor replacement for older facilities as existing motors aren’t rated to handle the alternating frequencies a VFD uses to modulate speed. The combination of mechanical and automation expertise on equipment retrofits can reduce your investment while producing the most effective solution.
Energy related projects in an HVAC application will continue
to increase in complexity to maximize investment returns. Because of
this, projects must be carefully implemented and tested to ensure
sequencing is designed and equipment is functioning as efficiently as
predicted. Although mechanical design firms can predict returns based
on compound sequencing they develop, coordination with the controls
contractor typically hampers project success. Most control systems are
only as robust and powerful as the programmer that is in charge of
translating the sequencing into logic. Proper selection of a design
firm and controls contractor is pivotal to maximizing returns,
especially when the majority of the project revolves around programming
About the Author
maintain an engineering sales position at Western Allied
Mechanical. Our business is consulting customers on energy consumption
and reducing costs through a joint mechanical and automation venture.
I’m an avid follower of the industry and am always open to new
opportunities and approaches. You can reach me
or my cell at 650-798-4154.
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