AutomatedBuildings.com Article - Simply Saving Energy

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.

Building 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.

Typical automation 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.

[an error occurred while processing this directive] 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 upgrades.

I currently 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 at zdenning@westernallied.com or my cell at 650-798-4154.

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