Frequently Asked Questions (FAQ) - Optimum Energy

Frequently Asked Questions about OptimumHVAC technology
This document is intended as a supplement to other technical information with answers to practical questions that arise when owners, operators and designers consider employing Optimum Energy’s OptimumHVAC software in their specific application. OptimumHVAC’s chiller plant design and operating technologies are based on the Hartman LOOP technology and are straightforward to apply, but certain aspects of these technologies such as chiller loading and sequencing control are quite different from traditional chiller plant operating concepts. Owners, operators and designers contemplating the use of these groundbreaking cost reducing technologies often have questions about whether their application is well suited to these technologies. OptimumHVAC has been evaluated for many climate regions and facility types and all issues that have been raised have been vigorously pursued such that an owner can be confident that OptimumHVAC can be implemented in any climate zone and will achieve the level of performance projected by Optimum Energy’s engineers.

BUSINESS RELATED

How does my organization acquire OptimumHVAC for our chiller plant?
Optimum Energy's technologies are patented technologies though available to all customers. The technology/products can be purchased directly from Optimum Energy, or though a certified integration partner.

How is the technology implemented?
You can purchase a site license and have the technology implemented through your existing control system or we can install our controller/translator, which communicates with all control systems. In addition to the control side, we require a minimum of one year of monitoring. The monitoring is our way of maintaining quality control and guaranteeing the performance we have projected.

What does the OptimumHVAC software license and monitoring cost?
The cost relates to the size of your plant and the equipment in your plant. If you fill out the BAF, we will be happy to provide a cost estimate. However, we have found that our pay back has been between 18 to 36 months, providing a 30% to 60% (Return On Investment) ROI, cash on cash. Additionally, Carbon Credits are available. In the U.S., Federal Tax Credits are available as well as utility rebates and incentives for implementing Optimum Energy’s OptimumHVAC.

What’s the process for purchasing OptimumHVAC?
If you would like to get specific information about your site, costs and time required, you may begin by either

taking our basic energy assessment which includes a site visit, a review of energy bills, and interviews with your facility management staff; or,
filling out the BAF available on this web site and sending it to us with the last two years’ electricity bills for the building or plant (if the plant is on a separate meter).

We ask what contractors you work with or if you have staff that will install the equipment. In either case, once we determine who is going to do the work we contact them, work through pricing, and provide a “road map” proposal. If the proposal meets your requirements we will arrange for one of our engineers to visit your site, confirm the equipment, piping configurations, etc. and plan the project. The local contractor or your staff will confirm and develop the final price. If you wish to proceed, the work is scheduled, we install our technology or controller translator and a DSL is installed. Our engineer is there for the commissioning process, which includes the start-up and training of building engineers and managers.

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TECHNOLOGY

Is OptimumHVAC the same as the Hartman LOOP?
OptimumHVAC is based on the Hartman LOOP algorithms and control sequences. Optimum Energy has taken what was originally a lengthy custom process of writing code and developing control sequences for each installation and developed it so it is now a software application that resides in an industrial PC that is a plug-and-play application for HVAC systems.

During the development process Hartman named these “LOOP” technologies because they employ integrated “closed LOOP” controls for the entire plant whereby the operation of all chillers, pumps and towers is coordinated in order to optimize total plant efficiency under all conditions. Most equipment in conventional plants operates in standalone fashion, responding only to certain temperature setpoints rather than operating in coordination with related equipment.

“LOOP” is also used to describe the chilled water distribution system in this technology which involves a fully determinant, single circuit chilled water loop instead of the common but less efficient indeterminate primary/secondary systems.

Therefore, we call the system designed for chiller plants OptimumLOOP

What is new about these technologies?
The most significant improvement of these patented all-variable speed chiller plant and distribution systems over conventional plants is the significantly reduced energy use in comfort conditioning applications. Under Optimum’s Applications , the entire chiller plant annual energy use usually averages about 0.6 kW/ton or less for most comfort cooling applications. This represents an annual energy reduction of 25% to 50% (depending on climate and application) below the most highly optimized conventional configurations of components of the same operating efficiencies. In Optimum Application chiller plants, all components are variable speed and chiller sequencing endeavors to keep chillers and towers operating at lower loads and flows rather than shedding them to keep the on-line equipment at high loading as in conventional plant operating strategies. To achieve these higher levels of performance, an entirely new approach to operating the equipment in chiller plants has been developed. Aside from the use of variable speed drives and the intelligence that allows these different pieces of equipment to operate in unison, the pumps, chillers and tower fans, plant configurations are very similar to conventional chiller plants. It is how the equipment is sequenced and operated with simple, straightforward and stable network based controls that is completely new.

In what applications are Optimum’s Applications most effective?
These Application technologies have been developed specifically for chiller plants that serve comfort conditioning loads. Industrial process loads may be suitable if the process loads are variable because this technology reduces energy use only at part load conditions. Warm, dry climates usually offer the best savings opportunities, but the technologies offer huge savings in comfort conditioning applications all over the world. The energy savings spectrum can estimate percentage savings on your HVAC energy consumption.

Estimated percentage savings

My contractors claim they can do the same thing. Is this true
The technologies are a result of millions of dollars in research and development and years of refinement. These technologies are protected by nine patents; however, they can be licensed by anyone.

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CONSTRUCTION COST ISSUES

Are construction costs higher for OptimumHVAC plants?
No, not necessarily. It is sometimes assumed that a cost premium equal to the cost of the variable speed drives less the cost of the across-the-line starters for the chillers, pumps and fans will be necessary. However, in many applications constructing an all-variable speed chiller plant in place of a constant speed plant of the same size and nominal efficiency costs about the same. Below about 80% loading, an all-variable speed chiller plant configuration incorporating variable speed chillers that are somewhat less efficient at full load, but cost the same as more efficient constant speed chillers of the same capacity, will begin to operate more efficiently than a conventional plant with the more efficient constant speed chillers. This means that when chiller plants are sized with a 20% or greater margin of excess capacity, the operating efficiency of an all-variable speed chiller plant incorporating OptimumHVAC will operate more efficiently even at peak load conditions than a conventional constant speed plant which loses efficiency when the equipment is oversized.

So, anytime a chiller plant is oversized for failure or standby protection the nominal efficiency of the chiller plant should be based on the actual peak load served by the plant rather than the total capacity of the plant. Doing so reduces the nominal full load efficiency requirements of variable speed plant components and therefore lowers their cost. This cost reduction, along with further reductions from effective network control connections, offsets the extra cost for the variable speed drives and allows all-variable speed chiller plants to provide substantial annual energy savings while costing about the same to implement as an optimized constant speed alternative of the same capacity.

Are the network controls required for an OptimumHVAC plant more expensive or complicated to operate than standard controls?
No. These controls are usually the same DDC controls that are employed in conventional plants. Most modern DDC systems have the capacity for network control, but it is seldom employed.

Is it cost-effective to retrofit an existing constant speed chiller plant to an OptimumHVAC plant, and if so, how is that accomplished?
Most existing chilled water plants can be cost-effectively retrofitted to employ OptimumHVAC Software. Chiller plants that are located in warm climates and do not employ effective tower optimization strategies are the very best candidates as they will provide the greatest annual energy savings.

Because OptimumHVAC's chiller plant software is modular, it is possible to upgrade a plant in stages, or to limit the upgrade to only certain elements of the technologies. For example, applying the technologies to the heat rejection circuits (condenser pumps and tower fans) is almost always a cost effective measure and therefore a good first step in an upgrade program. A heat rejection OptimumHVAC upgrade can be done without any configuration changes to the existing constant speed chillers. For chiller plants that serve large distribution systems, it is usually cost effective to convert the distribution system from primary/secondary to primary/booster and upgrade to OptimumHVAC's low power pumping technologies. Whether or not it is beneficial to convert the existing constant speed chillers and apply OptimumHVAC software depends on the age, efficiency and configuration of the current chiller plant. Please see business related questions for the process and to get a good first cut estimate of what the various upgrade options will cost and save.

Can any existing constant speed centrifugal chiller be upgraded to variable speed?
Like all existing motors, those that drive centrifugal chillers can be retrofitted with variable speed drives. Like other motors, if the compressor motor is in good condition, many years of excellent operation can be expected. However, there are some limits that may make variable speed conversion uneconomical. Some constant speed chillers cannot be significantly slowed due to minimum refrigerant pressure requirements or certain mechanical limitation. Chillers more than ten years old may employ refrigerants that are being phased out, and may operate at much lower efficiencies than modern chillers. Chiller plants with older, less efficient chillers may not be good candidates for variable speed upgrades. Because of low efficiency and lack of useful service life, it may be better to replace older chillers outright with new variable speed chillers, or focus immediate upgrade efforts on the heat rejection and distribution circuits. New variable speed chillers can then be retrofitted when the existing chillers reach the end of their useful life, or when scheduled as part of a refrigerant phase-out program.

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CHILLER PLANT OPERATION

How are the chillers staged in an OptimumHVAC chiller plant?
This is an entirely new method of chiller sequencing called the "Natural Curve" method of sequencing. The "Natural Curve" is a term coined to describe the most efficient operating load point of a chiller at various head (condenser and evaporator temperature) conditions. Typically, the Natural Curve for a constant speed chiller is at or very near full load at all head conditions, but for a variable speed chiller the most efficient operating point is at much lower loads and varies with the head conditions. Thus, a curve can be developed for variable speed chillers that plots their most efficient operating point at various head conditions, and this curve is called the "Natural Curve" of the variable speed chiller.

In this Natural Curve sequencing method, chillers (and towers) are staged such that the chillers operate at all times closest to their Natural Curve. Typically, in an OptimumHVAC Application plant chiller shedding occurs at much lower loads than in conventionally operated plants. As the load falls from full load, all equipment is operated at reduced speed until the Natural Curve algorithm calculates that the plant can operate more closely to the remaining chillers' Natural Curves if a chiller is shed. The same is true when a chiller is staged on. The exact points of this staged operation depend on the characteristics of the variable speed chillers and towers employed, as well as the current characteristics of the load served and the chiller head conditions.

Is control of chiller capacity included with speed control in OptimumHVAC operation?
Yes. Currently, a DDC controller is configured and programmed to operate chillers in an OptimumHVAC plant just as DDC controllers typically operate chillers in a conventional plant. Thus, the operation of variable speed chillers in OptimumHVAC chiller plants is very similar to the operation of conventional plants. Either you are on an Automation System or Optimum Energy's translator/controller controls both chiller sequencing (on/off control) as well as the amount of capacity (demand limit) of each chiller. All factory built variable-speed chillers include internal logic that is intended to continuously optimize vane and speed control to meet current conditions and variable speed chillers can also be configured to accept “demand” commands from the OptimumHVAC plant controller. Thus it is not difficult to establish OptimumHVAC plant operations with any variable speed chillers. In plants that are retrofit from constant speed chillers, the speed/vane control logic may be externally applied.

How realistic are the water flow, temperature values and power requirements employed in developing projected savings?
The values for outdoor dry and wet bulb temperatures come from actual weather data for the specific location chosen. Operating flows and temperatures are all within manufacturers’ limits for the chiller or tower to which they are applied. Pump flows and power requirements are calculated from standard manufacturers’ pump performance curves. Chiller and tower operating temperatures and power requirements at each load condition come directly from the ARI and CTI performance data for the equipment involved. This data has been determined from testing at those specific flows, loads, and temperatures. Therefore the values and power requirements are considered to be very realistic.

If chillers run longer at lower loads in OptimumHVAC plants, does that mean chiller maintenance costs will rise?
No, but this is a very important point. This question was first raised when the Hartman technology was being developed. We have discussed maintenance issues with chiller manufacturers and others who agree that chiller maintenance based on component wear will likely be reduced from the application of the Hartman technologies. The reason for reduced maintenance despite the longer operating hours of each chiller are

fewer starts
softer starts
lower average loading on each machine

While there is not yet sufficient data to show conclusively that maintenance costs are reduced in an OptimumHVAC plant, there is strong agreement among those expert in variable speed operations, including chiller manufacturers, that maintenance for wear and tear certainly does not increase.

Currently, much periodic chiller maintenance is triggered by runtime hours. It is generally agreed that for an Optimum plant these should be adjusted or replaced with new PM guides that recognize the reduced wear per operating hour that these plants achieve. Also, the newer studies that show mechanical failures are not generally reduced by periodic maintenance based only on run time, but only when maintenance is triggered by vibration, power or other operating anomalies.

Are there any new operating or maintenance issues that should be considered with an OptimumHVAC chiller plant?
Yes. Because these plants operate at reduced condenser water flows at low loads, there is the possibility of a greater rate of condenser tube fouling than with a conventional plant in some configurations. Because the flow is variable, it is difficult to precisely plan the frequency of required tube cleaning of an OptimumHVAC plant. This is one of the many reasons for the monitoring service that comes with the installation.

By monitoring the flow through the tubes we can determine when the tubes are beginning to foul and a tube cleaning is necessary. With regard to new plant design, if specific tube cleaning intervals are essential, there is a great deal of flexibility in an OptimumHVAC plant design and operations that should be considered by the designer or plant operations manager. To reduce the frequency of tube cleaning, the designer may decide to employ a three pass condenser bundle. This design can raise the flow rate in the chiller and eliminate any potential problem altogether. Once the plant is operating, the minimum condenser flow can be adjusted by the plant operators at any time to establish any tube cleaning intervals that are required.

These steps may have a small effect on construction or operating costs for an OptimumHVAC plant, but they can keep the tube cleaning at present levels, or even reduce the frequency of cleaning. Furthermore, there are now several different approaches to automatic tube cleaning that can be implemented to ensure that chillers operate at all times with the highest possible condenser heat transfer.

How does the owner know if OptimumHVAC software is performing as projected?
Optimum Energy employs low cost, real-time, web based, chiller plant efficiency monitoring into the plant controls. This added feature is of enormous assistance in operating the plant and managing maintenance activities. The energy performance instrumentation provides a continuous readout of the current total chiller plant operation effectiveness in kW/ton and accumulates data that can be compared with previous periods during which the plant operated under similar load and weather conditions. In addition to the alarm mechanisms built into the monitoring services the reporting information helps operations staff and management know very quickly when the plant operations stray from projected and historic energy use patterns, and it helps provide direction for getting the operation back on track.

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EQUIPMENT REQUIREMENTS

What type of chiller and cooling tower are required, and are these products readily available?
OptimumHVAC software is specifically developed for centrifugal chillers. Tom Hartman worked with the major chiller and cooling tower manufacturers during the development of these technologies. OptimumHVAC's plant configurations require that the centrifugal chiller be variable speed; all major chiller manufacturers make such variable speed chillers suitable for OptimumHVAC Applications. In the case of retro fits variable frequency drives are available for all chillers, cooling towers and pumps. OptimumHVAC requires that the cooling tower be a low head type with gravity or rotating sprinkler hot water distribution. Towers must also be constructed such that the tower works effectively with a condenser water flow turndown ratio of approximately 2.5:1. Many US and international manufacturers of cooling towers make such towers.

Are manufacturers concerned about applying their equipment in OptimumHVAC plants, and does OptimumHVAC's software have any effect on equipment warranty?
No. OptimumHVAC’s designs never exceed the operating limits for the equipment. There is no effect on warranty, and manufacturers are generally pleased to have their equipment chosen for this ultra-efficient application. While in some locations the local manufacturers’ representatives for chillers and cooling towers may not fully understand OptimumHVAC software or envision the widespread applications, the major manufacturers are supportive of these configurations for their equipment.

What type of control system is required in an OptimumHVAC plant to provide network control?
An OptimumHVAC chiller plant can be implemented with any of a number of Building Automation Systems (BAS) to operate the chiller plant and/or distribution equipment. The fundamental requirements are that:

The BAS has a functional and flexible programming language that uses floating point math and allows multiple layers of custom mathematical calculations and logic statements.
The BAS has extensive and automatic network management features such that each controller can employ point & variable data from any other controller in its control programs.
The BAS employs standard or gateway protocol features such that it can be connected to communicate with chiller and variable speed drive equipment.

Most of the existing DDC systems on the market today incorporate these features such that they are suitable for OptimumHVAC.

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DESIGN & OPERATION SUPPORT

What is the history and present status of these technologies?
Tom Hartman first began investigating the benefits of all-variable speed chiller plants in1992. At that time Tom encouraged manufacturers and industry organizations to develop this promising technology. However, none elected to do so. However, since the impact on plant energy use appeared to be very beneficial, Tom continued and made the investment to develop the technologies internally. Along with the development, Tom was encouraged by industry members to develop a mechanism for ongoing support since concerns arose that plant operators would not be able to tap their normal sources of operations information to keep all-variable speed plants operating at peak efficiency levels.

In 2005, Optimum Energy acquired the license rights to the Hartman technologies. Since then millions of dollars has been spent to further the development of the Hartman technologies. Optimum Energy plans to continue to invest at this rate for ongoing development and support for the Hartman technologies. These technologies are protected by nine patents (US Patent No. 5,946,926, US Patent No. 6,185,946, US Patent No. 6,257,007, US Patent No. 6,352,106, US Patent No. 5,535,814, US Patent No. 5,605,280, US Patent No. 5,725,148, US Patent No. 6,079,626, US Patent No. 6,607,140).

How are Optimum’s Applications and products supported?
At installation there is a training program at which your staff is trained in the operation and maintenance of the system. Additionally, this training is available on line to Site License holders and their staff. Site support services using our web-based remote diagnostic tools are available in a range of plans depending on customer requirements.

The ongoing support program offers additional support for plant operations staff with on-line information, Q&A resources, a call center, and access to the Internet based OptimumHVAC users group. Ongoing support services also include direct contact channels to OptimumHVAC operations specialists for assistance in troubleshooting for an initial one year period which can be easily extended to the entire life of the plant if desired.

In the case of new buildings, experienced designers know that in order for a newly developed technology to be implemented effectively, the design team should have access to special expertise in that technology throughout the design and implementation process. In OptimumHVAC projects, this can be accomplished with direct engineering support for the design and construction team.

In these cases the following services are available:

Engineering and design review services to the owner, designer or contractor to assist in developing the configuration of chillers, towers, pumps, piping and controls that is most suitable for plant needs and to ensure optimal plant operation and performance.
Specifications for critical elements of the plant that include the chillers, towers, and control systems, along with procurement services in order to ensure that the purchase of major equipment employs value analysis principles in a “pre-purchase” or similar process that fits the needs of the owner’s organization.
Construction services to review and support the control contractor’s software and hardware design, and assistance to the startup, test and balance, or commissioning agencies in order to ensure that the OptimumHVAC hardware and software are implemented correctly and that optimum operational efficiency of the plant is achieved.

The cost of this service varies depending on the amount and areas of support that are identified as necessary.

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