Site Controls

Help your customer manage building operations for energy savings.

By Dodd Brown

Over the past few years, many petroleum marketers placed their resources predominantly on environmental items, with little or no focus on the daily operational costs of the store. The next challenge is the conscious movement in a “green” direction while planning new construction or updating current operations. Some of the many items to consider are building controls for whole-site operation, including the following:

• Energy
• LED lighting
• Solar panels
• Tankless hot water heaters
• Thermal reduction roofing material
• Easy landscaping like synthetic grass
• Daylighting with skylights
• Occupancy sensors for back rooms and restrooms
• Groundwater recovery tanks instead of retention ponds for irrigation
• Recyclable building materials and equipment.

Enhancements could be as simple as incorporating automatic site lighting controls and programmable T-Stats to whole-site system controls, aka building management systems (BMS). Some enhancements add upfront cost to construction budgets in new stores or pull from operational budgets in existing stores. However, each type provides some amount of payback for your customer's investment.

Control Options and Green Goals
Generally, the major energy users in a petroleum operation are exterior lighting at 25-35 percent, HVAC at 15-25 percent, refrigeration at 9-18 percent, hot water heater at 1-3 percent and cooking equipment (where applicable) at 3-7 percent. The percentage breakdown varies on square footage of the store and food offerings.

Work with your customer to determine what they want to achieve in the management of their daily operations. Below are some “green” goals:

• Reduced overall energy usage
• Better control of site lighting for marketing and safety
• Possible federal/state/local tax incentives
• Utility incentives/rebates for using controls that limit demand during peak hours
• Demand control to help reduce peak demand cost
• Monitoring equipment run time for preventive maintenance programs
• Reconciliation of utility bills
• Better control for sites already in operation
• Remote connectivity for monitoring and programming or stand-alone at store level
• Monitoring operation within set points for HVAC, coolers/freezers, etc.
• Data logging of product temperatures, i.e., deli cases or coolers/freezers
• Data logging of electrical usage
• Open protocol for sharing controller information to or from other site devices
• Control power demand (load shed) utilizing current transducers on the main service power feeders to monitor site power load and shed devices during high demand
• Daylight harvesting to turn off select interior lights based on ambient light level within the store.

Lighting
Today's sites, in large part, are dependent on store personnel for control of the exterior lighting. Lighting is controlled by a wall switch, which energizes a complete electrical panel board dedicated to lighting only. Another practice is the addition of a basic time clock (single-stage clock with no photocell). A photo eye might be added to turn on automatically should it be an overcast day.

The challenge with this, besides the human element, is that all the lights are on or off at the same time. There is no staging to reduce electrical demand when lighting is switched on. Most non-essential lights (pole/canopy/soffit) run for several hours a day longer than necessary, switching on too early in the afternoon and switching off later in the morning.

Options › A simple lighting control system can provide multiple staging levels for lights such as signage first, canopy second and site lighting third. Most allow the ability to automate the lighting loads by time of day, as well as photocell input to determine which lights are necessary based on actual ambient light. There are overrides for the individual stages for service or special events. This removes the need for store personnel to enter programs or modify selected set points. Return for this type of unit can be between 16 and 36 months, depending on site lighting demands. An additional benefit is daylight harvesting of interior lights in stores that have good natural lighting to cycle ceiling fixtures.

HVAC
This is an area of the store where most think there is not much to gain; it is either on or off. In some aspects, this is true. However, it is a large part of the electrical usage and an area that might be abused the most at store-level operations. HVAC is controlled by a local wall T-Stat in the store space that it is cooling or heating. In most stores, these T-Stats have a slide switch on top to adjust set points. Operators generally add a plastic cover to prevent tampering of desired set points. Most store personnel have learned that a paper clip is all that is required to get around the plastic cover and change set points. Constant changing of temperatures up or down a few degrees in either direction uses more energy. There is no return on this design.

Options › The simplest solution is to replace with a programmable T-Stat to prevent tampering, as it has no slide switch. Most entry level controllers have additional features to maintain desired temperature set points for customer comfort, a night setback of a few degrees during non-peak customer hours or at locations that are not 24 hours and set point lockout for min-max. This design doesn't allow remote alarming, programming or monitoring.

A BMS system uses space sensors in the store, but control resides in the system. HVAC is directly controlled and store level tampering is removed. Programming and monitoring can be done remotely for alarms and notification when outside of operational set points via e-mail or text messages. Supply sensors view the air entering the space. This helps to determine the operation of a unit prior to sending service personnel. The HVAC can be controlled based on predetermined criteria to reduce electrical demand at peak occurrences.

Refrigeration
Local control of refrigeration is done via the manufacturer's device. There is no alarming at the store level or remote communication for out-of-range operation. This requires manual data logging of temperature points during the day where required.

Options › Several third-party devices for basic store level alarming are available. Some offer data capabilities. BMS enables remote monitoring of cooler/freezer and deli case temperatures for out of limits and provides local or remote alarms via e-mail/text messaging with real time information. Door switches notify when doors are open too long during deliveries or stocking. Problems are detected prior to store personnel becoming aware.

Cooking Equipment
Devices that are manually controlled by switches are not turned on in time for proper warmup for business, or they are left on when they should be off.

Options › Depending on the type of food service, several electric devices could be turned on and off automatically and controlled and monitored. A whole-site system also could interlock power into demand control for powering off for short cycles.

Hot Water Heater
The most important item to address with a hot water heater is the need to maintain the proper temperature levels for health regulations. Local control is typically provided via manufacturer's device, which offers no provision for set point notification.

Options › You can install a sensor to monitor temperature for alarming outside of parameters and potentially demand control (electric type) during peak demand for short cycles as part of a whole site program.

Controlling Costs
Many options of all budget ranges are on the market to help your customer control the bottom line. Even a small investment can have a considerable impact on overall operations, along with starting to shape green business goals and public image.

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The PEI Journal • First Quarter 2009 • Volume 3, No. 1 • Contents are Copyright © Data Key Communications, Inc.
All rights reserved. • Nothing may be reproduced in whole or part without written permission of the publisher.