Pump cavitation is most commonly found with centrifugal pumps. As the liquid enters the pump’s suction port, the impeller’s rotation creates a change in speed. Bernoulli’s principle states that as a liquid’s velocity increases, the static pressure decreases. In the case of cavitation, the liquid changes to bubbles. Eventually, the pump’s the static pressure will go back up causing the  cavitation: the implosion that happens from the bubble collapsing back to liquid.

Identifying Pump Cavitation

Pump cavitation can be heard and seen. It will sound like  rocks or marbles going through the pump. You can also see cavitation damage to your pump’s internal surfaces. The continual metal loss cavitation causes can form pitting in the metal.

Why is Pump Cavitation a Problem?

The collapse of the vapor bubbles erodes the impeller surface and pump casing. These issues decrease pump efficiency—resulting in higher energy use, additional repair costs, and reduced pump lifespan.   If strong cavitation occurs at the pump inlet, pump performance decreases, which can lead to premature pumping failure.

4 Types of Pump Cavitation

1. Air Aspiration Cavitation

Air is unpredictable and can sometimes be sucked into a pump through failing valves or other weak components. The air will eventually start to form bubbles that then gets popped under pressure by the pump impeller. Some tips to prevent this type of cavitation include:

• Check all O-Rings and mechanical seals
• Ensure all piping is crack-free
• Make sure joint rings have not perished on any suction piping

2. Internal Re-Circulation

This type of cavitation prevents the pump from discharging at the desired rate, meaning that the liquid will now re-circulate around the impeller. The liquid travels through low- and high-pressure zones resulting in heat and high velocity. This, in turn, creates vaporized bubbles. This can be causes by operating too close to shut-off head, a closed discharge valve or even an over-pressurized header.

Some tips to prevent this type of cavitation include:

• Opening a restricted discharge valve on the pump
• Checking for clogs in the downstream filter
• Checking pressure at the discharge line

3. Turbulence

If the system has been designed with parts that are inadequate for the amount of liquid being pumped, it will in turn create vortexes. These vortexes will become turbulent and experience major pressure differences throughout the system. This all leads to erosion of solid materials over time. Some tips to eliminate or avoid turbulence in your system include:

• Design pump suction piping and routing to avoid excess turbulence
• Ensure the system sufficient Net Positive Suction Head (NPSHa)
• Work within maximum allowable flow limits
• Increase pump suction line size as necessary

4. Vane Syndrome

This cavitation occurs if the pumps impeller uses too large of a diameter or the housing coat is too thick. Both problems here create less space throughout the pump housing. The pump will then have an increased velocity in the liquid from the small amount of free space available, which in turn leads to lower overall pressure. Cavitation bubbles will occur because the lower pressure is now heating the liquid. Some tips to prevent this cavitation include:

• Ensure there is ample free space between the impeller blade tips
• Ensure the sufficient free space between your impeller and its housing.  It is recommended this be at least 4% of the impeller’s diameter.

What to do if Pump Cavitation is Suspected

If cavitation is suspected, it is best to have this condition reviewed by a qualified liquid handling specialist. The specialist will investigate whether the pump’s inlet pressure is higher than the inlet pressure required by the pump manufacturer. To do so, they will look calculate the pump’s inlet pressure and compare this to a pressure reading at the pump’s discharge port. This information, coupled with manufacturer’s pump curve to identify the GPM , will allow them to make recommend any operational improvements or repairs.

Compressed air is one of the most expensive utilities in any industrial or manufacturing setting. These systems can vary widely in efficiency and are often ignored in favor of more pressing and urgent demands such as pressure levels and air quality. Often times, the efficiency of these systems is impacted by equipment, lack of maintenance or even the system configuration itself. However, there are things that can be done to improve the performance of these costly systems.

1. Monitor the Compressed Air System

First and foremost, a baseline for your compressed air system is crucial. Without a proper picture of typical operating parameters, improvements cannot be successfully identified or implemented. Measurements should be taken on key parameters such as pressure, power, flow and dew point. Once collected, these factors can be monitored to note deviations from the normal operating performance and the success of corrections to these identified issues can be confirmed.

2. Implement Compressed Air Leak Detection & Repair Program 

Studies have shown that anywhere from 20-40% of compressed air fails to make it to its intended destination. Having a plan in place to detect and repair leaks can recover a large amount of utility costs. The simplest form of detection can simply be staff using their ears to listen for leaks and tighten up piping appropriately. There are also ultrasonic leak detection products that can be utilized for more precise detection. Even the manual detection process and corresponding corrections can save 10-15% on a site’s energy bill.

3. Check Component Pressure Loss

It’s critical to keep an eye on how much pressure differential exists between the piping drop and the compressed air’s end use. Often times, a large pressure differential will occur in the last 30 feet of pipe as this is often the home of undersized filters, regulators, connectors and hoses-all elements that can contribute significantly to a sizable differential. Why is this problematic? When there is an extreme differential in pressured in this section of the compressed air system, the discharge pressure at the air compressor itself must rise to compensate. This increases power costs. Giving proper consideration to the size and care of these components can reduce wear on this equipment, minimize leaks and reduce energy costs.

4. Modify Plant Piping

Many plants grow overtime, increasing compressed air demands that are too much for the original piping to accommodate. When this happens, the undersized compressed air piping can cause flow issues that force the compressor discharge pressure to increase to compensate. Continually monitoring compressed air piping differential pressures will identify whether this becomes a costly problem that can be resolved with piping configuration and sizing modifications.

5. Adjust Compressed Air Pressure

Often times, the compressor discharge pressure is higher than it needs to be-the higher the pressure, the more energy it consumes. There can be several reasons for this but often the pressure is set to the compressor rating without consideration given to the plant’s actual pressure needs.  By ensuring equipment is operating to actual needs instead of manufacturer specs, facilities can reduce this excess pressure that causes compressors to consume more energy than necessary.

6. Optimize Ancillary Compressed Air Components

The air from a compressor must be conditioned so that it doesn’t contaminate other equipment with oil residue or moisture. This can be an energy intensive process depending on the type of air driers being used to filter and remove contaminants from the compressed air. Selecting more efficient air driers that reduce power consumption in this process, whether by efficient design, low or no purge flow or lower pressure differential, can add up to big operational savings. Every psi counts.

7. Efficient Compressor Controls

Most compressors and air driers are not being controlled efficiently. With regard to individual compressor controls, there are various modes of operation with corresponding levels of efficiency. Inlet modulation mode, for example, is the least efficient way to control any compressor that is running at part load but may be acceptable if the compressor is always at or near full load. Conversely, the variable speed mode is the most efficient way of controlling compressors at part loads but may not be the most efficient at full loads. Preparation and planning needs to go into setting up and coordinating multiple compressor systems to ensure the system is operating at an efficient level.

To assist with this, consider compressed air control systems to ensure the correct compressors are running at a given time, equipment is running smoothly, and that the system pressure is held within specified limits.

8. Utility Incentives

Many utilities support compressed air improvements and provide financial incentives for initiatives that reduce energy costs. Most will at least fund an audit to identify areas for improvement and many will fund a significant portion of the investment needed to achieve these improvements.

Utility Bill Basics

Most commercial and industrial sites have utility bills that are divided into two major categories:

1. Energy consumption: the amount of energy (kWh) consumed, multiplied by the relevant price of energy ($/kWh) during the billing period.
2. Demand: the maximum amount of power (kW) drawn for any given time interval (typically 15 minutes) during the billing period, multiplied by the relevant demand charge ($/kW). 

Sites trying to save on their energy bill may attempt to estimate savings based on energy consumption as calculated above.   The problem with this approach, however, is that it doesn’t take into account the second category, demand charges. Peak demand charges can account for 30 to 60 percent of a facility’s annual electric spend.

What Are Utility Demand Charges?

Demand charges exist to incentivize customers to spread their energy usage over time. This is because utilities must maintain enough generation and distribution capacity to meet the needs of all customers during the points in time when the most energy is drawn from the grid. This requires a large amount of expensive equipment to be kept on standby. Through demand charges, customers that draw a lot of power over short periods of time contribute more to the costs of building and maintaining the necessary infrastructure needed for peak times.

Demand is a measure of how much power a customer uses at a given time. The structure of the demand charge varies by utility but it will be based on the maximum amount of power that a customer used in any interval, typically a 15-minute period.

Calculating Utility Demand Charges

To determine the demand charge for a given month, the maximum power demand is multiplied by the demand charge rate of the prevailing utility rate. Some rate structures include multiple types of demand charges, with higher charges during hours of peak demand, and lower charges during “partial-peak” or “off-peak” hours.

Offsetting Utility Demand Charges

First and foremost, sites must understand when and how electricity is used. Utility companies will provide detailed breakdowns of energy consumption throughout the month.

Once a baseline is established, energy use optimization strategies are the first step in reducing site demand charges.  One common source of demand spikes are HVAC systems. Xpress ® from tekWorx ensures the most efficient combination of cooling equipment is in operation, reducing spikes and demand charges. Xpress ® utilizes real-time adaptive control algorithms to take into account parameters like weather and chiller efficiency curves to make intelligent equipment sequencing decisions that use only the necessary equipment and capacities to satisfy cooling needs. The system’s dashboard also tracks real-time site utility costs as show below. 

Many utility companies offer programs to lower, offset, or eliminate demand charges. Most of these programs require the utility company to manage a site’s loads during peak times. If a site has the flexibility to switch to an alternate energy source during peak times, such programs could prove beneficial and cost-effective.

Lastly, solar panel systems have the potential to reduce demand charges in the right setting. A solar system generates electricity from the sun allowing a site to use solar-generated electricity as opposed to utility-generated electricity. If, however, a spike in demand on a cloudy day or in the evening, demand charges will follow accordingly. Solar solutions can be used in tandem with battery storage to store energy generated from the solar panels to be used during peak times.

Energy Management System (EMS) Basics

Energy management systems (EMS) are computer-based systems that measure a site’s energy consumption and look for areas to improve energy efficiency.  Energy management system platforms improve energy performance by detecting, monitoring, and controlling energy consumption and costs.  

EMS are primarily a reporting tool, as they are used to track information and record it over time. They are useful for sites that want to monitor and manage their energy expenditures such as water, electricity, steam, gas, and heat.

What is a Building Management System (BMS)?

A building management system or building automation system is a computer-based system that automates the control the buildings’ mechanical and electrical equipment such as ventilation, lighting, HVAC, power systems, and fire and security systems. The BMS is used to make sure the mechanical systems work individually, but also in conjunction with each other, to determine that the building can operate effectively and keep occupants comfortable. A BMS typically lacks the energy efficiency insights of an EMS.

How can an Energy Management System impact efficiency?

Energy management systems meter, submeter, and monitor functions that allow facility and building managers to gather data and insight that allows more informed decisions about energy activities in properties and sites. EMS can benchmark energy use with other nearby buildings and track weather changes to project expected future facility behavior, identify savings opportunities, and reduce energy expense overages.

Can an Energy Management System Work with a Building Management System?

Yes, EMS and BMS are quite compatible. An EMS can function as an overlay on pre-existing BMS/BAS system or it can also work alone. EMS functionality has been added to many BMS and vice versa over the years as facility managers want to optimize energy consumption in their building for sustainability purposes and/or to reduce costs that were being spent on excess energy consumption.

What BMS and EMS work best together?

tekWorx bridges the gap between BMS and EMS with Xpress® , an easily installed energy savings platform that significantly lowers the energy consumption, and therefore the cost, necessary to meet temperature requirements for commercial, institutional and industrial facilities.

The Xpress® optimization solution can be overlaid with the building’s existing BAS and control hardware.  Xpress® adaptive algorithms determine the most efficient settings for all equipment responsible for cooling production in real time (chillers, valves, pumps, drives, AHUs, etc.) and passes these instructions to the BAS to execute. These two platforms then work in tandem to provide complete HVAC system operational control, energy optimization and performance monitoring and ensure the most energy efficient combination of cooling equipment is in use 24/7/365.

In 2016, after being purchased by FCA, it was announced the auto giant would invest $1.48 billion to again retool the Sterling Heights Assembly Plant (SHAP) site to build the next generation Ram 1500 and support the future growth of the Ram brand. The overhaul included an upgrade of the South paint shop and its Energy Center which houses chillers, hot water generators, pumps, purified water equipment, non-potable water supplies and associated equipment.

tekWorx blue ribbon was presented for the Xpress® control and optimization solution that optimizes the chilled water equipment at the SHAP South Energy Center. tekWorx Xpress® optimization algorithms continuously adjust equipment sequences and key setpoints based on parameters related to process requirements and outdoor air temperature.  This ensures maximum system efficiency in real‐time while maintaining cooling requirements at the lowest total kW per ton.

Xpress®, combined with the energy impact of YORK® YMC² magnetic-bearing chillers, has resulted in an average annual total system efficiency of 0.42 kW/ton over the last three years. Xpress® optimization mode saves the Energy Center nearly 3,000,000 kWh annually and reduces yearly energy expenses by approximately $175,000.

About the ASHRAE Technology Awards

The ASHRAE Technology awards are an international competition that recognize outstanding achievement in the design and operation of energy efficient buildings. Winning projects incorporate ASHRAE standards for effective energy management and indoor air quality and serve to communicate innovative systems design.

Visit this link for more information on the ASHRAE Technology Award and this year’s list of winners. The SHAP optimization project will be featured in ASHRAE Journal’s August issue.

Free cooling refers to any technique used to reduce the energy consumed by cooling systems, or the time that the cooling units run, by using the outside temperature of air or water to cool the facility. Generally, it comes from the use of air-side and water-side economizers. But how does it save energy?

What is Free Cooling & How Does it Save Energy

For facilities with water- or air-cooled chilled water plants, free cooling is an economical method of using low external air temperatures to assist in chilling water, which can then be used for industrial processes, or air conditioning systems.  Used in the cooler months of the year, such systems can be made for single buildings or cooling networks. Free cooling can also extend the working life of installed cooling systems, lowering the energy and maintenance costs for facility owners.

The cooling provided, of course, is not completely “free” because the tower, chilled water pumps, and tower fans still must be operated. Nonetheless, it allows cost conscious building or process owners and operators to take advantage of naturally occurring climate conditions to save system operating costs.

Free Cooling & Economizers

Free cooling strategies rely on economizers. Economization is accomplished by taking advantage of the temperature difference between indoor and outdoor ambient conditions rather than running compressors to provide the cooling. The effectiveness of an economizer depends on loads characteristics of the building, type of HVAC system and the local climate.

Economizers draw in outdoor air and mix it with return air from indoors.  Airside economization can be accomplished by pulling cool dry air straight into the building, which is the simplest and most efficient option in many cases. Waterside economization, in contrast, uses an indirect method of economization and pulls cool water from a cooling tower or dry cooler that is cooled by outdoor air and runs the water through coils inside the HVAC units in the building.

Waterside Economizers

A water-side economizer eliminates the need for cooling via compressors and is an effective way to maintain temperature and humidity requirements while reducing or eliminating chiller use.

Water-side economizers are best suited in climates where the wet bulb temperature is lower than 55°F for 3,000 hours or more. This describes the majority of the United States, barring areas in the extreme Southwest and portions of the Southeast. They are commonly used in data centers, which produce a near-constant internal cooling load, and provide an extra level of cooling redundancy in the event of chiller failure.

Water-side economizers are preferable to their air-side counterparts for applications in which specific minimum humidity levels are called for, such as laboratories and hospitals. The waterside economizer requires a winterized cooling tower in many climates. Since the tower is expected to operate when it’s cold outside, it cannot be seasonally drained.

Airside Economizers

Airside economizers are a duct and damper arrangement that allow a cooling system to supply outdoor air to reduce or eliminate the need for mechanical cooling during mild or cold weather. At outside air temperatures below 55 F, the compressors are not required to run, which conserves energy. In turn, cooler outside air is used to cool the space, hence the term “free cooling.”

Common Free Cooling Strategies

Determining the most effective free cooling strategy varies by facility. Below are three of the most common strategies.

Strainer cycle: In this system, the condenser and chilled-water systems are connected. When the outdoor wetbulb temperature is low enough, cold water from the cooling tower is routed directly into the chilled-water loop. Although the strainer cycle is the most efficient water economizer option, it greatly increases the risk of fouling in the chilled-water system and cooling coils with the same type of contamination that is common in open cooling-tower systems. A strainer or filter can be used to minimize this contamination, but the potential for fouling prevents its widespread use.

Refrigerant Migration: In this system, valves are open between the condenser and evaporator of the chiller when the compressor is off. This allows free migration of refrigerant vapor from the evaporator to the compressor and of liquid refrigerant from the condenser to the evaporator.

Plate-and-Frame Heat Exchanger (HX):  Another way to reduce the energy consumption of a chilled-water plant is to precool the water in the chilled-water loop before it enters the evaporator. This can be accomplished by piping a plate-and-frame heat exchanger into the chilled-water and condenser-water loops. When the ambient wet-bulb temperature is low enough, the heat exchanger transfers heat from the chilled water returning to the evaporator to the condenser water returning from the cooling tower. Precooling the chilled water before it enters the evaporator lessens the cooling burden, reducing the energy that the chiller uses.

Free Cooling & Proper Controls

Energy savings from free cooling rely on the appropriate design and controls to work optimally. Economizers add another level to the cooling scheme and must be engineered into the air handling system and controls. Interactions between the economizer and mechanical cooling (condenser pump, tower fan, chilled water pumps, fans, etc. ) must also be seamless and well-defined to ensure energy savings are achieved.

Coupling a free cooling system with an optimization solution like Xpress® allows seamless monitoring and management of all cooling equipment. Along with live and historical data capture, Xpress® combines real-time algorithms and extensive HVAC design experience to automatically optimize operating settings for equipment, maximizing free cooling and reducing energy costs.

Why do utilities offer commercial utility rebates and incentives?

Reducing energy costs through energy efficiency and demand response programs is good for both facilities and utilities. Utilities benefit from reducing energy consumption demand at peak times by avoiding the need for building additional capacity. Also, as more utilities are faced with competition, responding to customer requests with energy service programs increases retention.

Are commercial utility rebates and utility incentives the same thing?

These terms are used interchangeably but they are not the same thing. A rebate is a return of part of an original payment. An incentive, on the other hand, is intended to initiate action. Without it, that action would likely not occur.

Many programs are structured as either a rebate program or an incentive program. Depending on the program, they are either giving a site money back for an already planned project, or they are trying to entice a facility to move forward with something you wouldn’t have normally pursued.

What other commercial and industrial rebate and incentive programs do utility providers offer?

Beyond general rebate and incentives, there are demand response and load management programs. These programs provide incentives for facilities to curtail demand during peak energy usage periods.

Load management, or demand response, is a utility’s solution to decreasing high load demand on its electrical system. If the demand is peaking or extremely high, usage is reduced in one of two ways:  temporarily managing, or shutting off, electric loads using a radio-controlled switch or applying a significant charge if electricity is used during that time.

Are there different types of commercial utility rebates and incentives?

The two types of utility incentives offered for commercial and industrial buildings include service incentives and cash rebates.

With the service incentive, the utility company pays an engineering firm or other service provider directly for their technical services, such as retro commissioning or energy assessments. The incentives vary based on the utility provider.

With a cash rebate, the utility provides the commercial building owner with rebate based on the energy impact of the installation of energy efficient equipment and/or services.

Are there different types of commercial utility rebates?

There are two types of utility energy rebates: prescriptive and custom.

Prescriptive rebates are based on installing approved energy-efficient equipment or taking other energy saving measures that meet a defined set of criteria. These incentives are predetermined dollar amounts for the most common replacements seen in the market such as high efficiency drives and motors. Prescriptive incentives do not require pre‐approval unless the incentive is over a certain amount and can be applied for after installation.

Custom utility rebates are based on energy savings, which must be measured and verified-both pre-installation and post-installation by the utility. Facilities or their consultant work with the utility to determine equipment eligibility, measurement and verification processes and potential rebate amounts prior to the beginning of the project. They often require site-specific assessments. Once the project is complete, the verified demand and energy/water savings from qualifying equipment will determine the final amount of the rebate. Some custom rebates can significantly reduce the payback period associated with the new equipment or project.

Are commercial utility rebates and incentives available for new construction?

Incentives are often available for ground-up construction, additions or expansions, and complete building repurposing. These program encourages  building owners and designers to evaluate and install systems with higher energy efficiency than the standard or planned systems.

What is the process for securing commercial utility rebates and incentives?

To secure these utility incentives, sites work with either the utility company or their liaison hired to administer the program or with an industry professional, such as a consulting engineer, contractor or energy efficiency firm.

Is there a list of all available utility rebates and incentives?

The most comprehensive list of incentives and rebates offered in each state is accessible with DSIRE.  Established in 1995 and funded by the U.S. Department of Energy, DSIRE is an ongoing project of the NC. Solar Center and the Interstate Renewable Energy Council. This database is a great source of information on state, local, utility and federal incentives and policies that promote renewable energy and energy efficiency.

There are plenty of opportunities to utilize energy-efficient incentives that save energy and dollars each month. tekWorx Xpress® optimization solutions qualify for significant custom HVAC rebates with all utility providers and our engineers assist with all applications, verification and paperwork.  

Ground Source Heat Pump Basics

Ground source heat pump systems are highly efficient because they move heat from place to place, instead of generating it from a fuel source like oil, natural gas or electricity.

A commercial geothermal heat pump operates on a simple principle: it moves heat from one place to another via a refrigeration process. In a commercial building, a series of heat pumps removes heat from an energy supply source in the ground. The heat pump concentrates this low-grade heat, raising its temperature and then transfers it to the building’s energy distribution system via a heat exchanger.

In the summer, the process is reversed. The heat pumps collect heat from the building and deposit it into the ground loop, providing cooling.

Since the ground maintains a constant temperature of 55­­-70°F depending on location, a geothermal HVAC system can save 25­­-50 percent on HVAC costs compared to conventional systems using air­ source condensing units for cooling and fossil fuels for heating.

Types of Ground Source Heat Pump Systems

There are three basic types of loop systems and their uses depends on the climate, soil conditions, available land, and other site-specific considerations.

1. Closed-Loop Systems

Closed-loop systems are those in which heat-transfer fluid continuously circulates in a closed loop that’s filled just once and used again; no fluid can escape, and no outside materials can enter. Because of this, most closed-loop geothermal heat pumps circulate an antifreeze solution through a closed loop — usually made of plastic tubing — that is buried in the ground or submerged in water. A heat exchanger transfers heat between the refrigerant in the heat pump and the antifreeze solution in the closed loop.

Closed loop geothermal ground loops can last 50+ years with little to no maintenance. Once installed, the buried ground loop will be a permanent fixture on the property for as long as there is a building to heat and cool.

For commercial and industrial applications, the loop can be in two types of configurations:

• Vertical GSHP Configuration

Large commercial buildings and schools often use vertical systems because the land area required for horizontal loops would be prohibitive. Vertical loops are also used where the soil is too shallow for trenching, and they minimize the disturbance to existing landscaping. Vertical loops are connected with horizontal pipe, placed in trenches, and connected to the heat pump in the building.

• Pond/Lake GSHP Configuration

A pond / lake ground loop is a series of plastic pipes filled with heat-transfer fluid and submerged in a nearby pond or lake with adequate size, depth, and flow. The loop connects to an indoor geothermal heat pump and uses the pond or lake water as a heat source or heat sink.

2. Open-Loop Systems

An open-loop geothermal system pipes clean ground water directly from a nearby aquifer to an indoor geothermal heat pump. After the water leaves the building, it is expelled back through a discharge well. The water may also be directed into a local pond or approved drainage ditch. This option is practical only where there is an adequate supply of relatively clean water, and all local codes and regulations regarding groundwater discharge are met.

The performance of an-open loop system may degrade over time if water quality issues like silt, sediment or high mineral content are present or if the water supply diminishes for any reason.

3. Hybrid Systems

Hybrid systems use several different geothermal resources, or a combination of a geothermal resource with outdoor air. Hybrid approaches are particularly effective where cooling needs are significantly larger than heating needs. A hybrid system uses conventional technology such as a cooling tower or boiler to meet a portion of the peak heating or cooling load. This innovation allows for a smaller, less expensive heat exchanger.

Maximizing Ground Source Heat Pump Efficiency

Ground Source Heat Pump systems are the leading technology chosen by building owners and entities seeking to achieve LEED, Living Building and Net-Zero Energy Certifications. They are also recognized as building environments that are healthier, more comfortable and more profitable. GSHP heating and cooling systems allow a facility owner to invest in their business on things such as product R&D, new equipment, or increasing personnel.

The design of reliable, cost-effective, energy-efficient GSHPs requires a system approach, as well as HVAC wisdom. tekWorx Approachable Experts® can help your facility incorporate existing plant equipment, including geothermal systems, into a comprehensive cooling optimization strategy.

What are Net Zero Energy Buildings?

Most Net Zero Energy Buildings (NZEB) are still connected to the electric grid, allowing for the electricity produced from traditional energy sources (natural gas, electric, etc.) to be used when renewable energy generation cannot meet the building’s energy load.  Conversely, when on-site energy generation exceeds the building energy requirements, the surplus energy should be exported back to the utility grid, where allowed by law. The excess energy production offsets later periods of excess demand, resulting in a net energy consumption of zero.

Most Net Zero Energy Buildings (NZEB) are still connected to the electric grid, allowing for the electricity produced from traditional energy sources (natural gas, electric, etc.) to be used when renewable energy generation cannot meet the building’s energy load.  Conversely, when on-site energy generation exceeds the building energy requirements, the surplus energy should be exported back to the utility grid, where allowed by law. The excess energy production offsets later periods of excess demand, resulting in a net energy consumption of zero.

Energy Efficiency and Net Zero Energy Buildings

Energy efficiency is generally the most cost-effective strategy with the highest return on investment, and maximizing efficiency opportunities before developing renewable energy plans will minimize the cost of the renewable energy projects needed. Using advanced energy analysis tools, design teams can optimize efficient designs and technologies.

Energy efficiency measures include design strategies and features that reduce the demand-side loads such as:

• High-performance Envelope: The building envelope is made up of many different components: roof, walls, windows, doors, etc. The building envelope acts as a thermal barrier, playing an important role in regulating interior temperatures and determining the amount of energy required for optimal thermal comfort. Creating a high-performance building envelope means each piece is designed to minimize the transfer of thermal energy in both directions. This decreases cooling loads during summer and heating loads during New constructions provide the best opportunity to deploy a high-performance building envelope, since it can be built into the project.
• Air Barrier Systems: The basic function of an air barrier system is to prevent uncontrolled air leakage through the building enclosure. An air barrier must be a complete system of materials and components that work together to truly provide a continuous barrier to air flow
• Daylighting: Daylighting is the practice of placing windows, skylights, other openings, and reflective surfaces so that sunlight can provide effective internal lighting, reducing the amount of energy needed for heating and cooling. The process of daylighting also includes controlling how much natural light(both diffuse and direct) enters a building and is generally accompanied by lighting control systems that are responsive to the amount of daylight entering the building.
• Passive Solar Heating:  These systems  collect heat as the sun shines through south-facing windows and retains it in materials that store heat. For example, greenhouses and sunrooms are examples of passive designs. The sun’s rays pass through the windows, and the structure’s interior absorbs and retains the heat.

Once building loads are reduced, the loads should be met with efficient equipment and systems. This may include:

• Energy efficient lighting:  Energy-efficient CFL or LED lighting fixtures offer some substantial advantages over traditional lighting. Not only do these lights use less energy to light the same area as incandescent or traditional fluorescent lights, but in most cases they give off less heat. This reduces the need to cool the building in the warmer months. No matter how energy efficient a lighting system is, the energy is being wasted if no one needs it. Consider occupancy sensors which can help prevent light and energy from being wasted.
• Cooling Optimization: Chilled water can account for up to 35% of HVAC energy costs. Optimization solutions very in their approach but work to produce this chilled water more efficiently. tekWorx Xpress® solutions continuously adjust equipment sequences and key setpoints based on parameters related to process requirements and outdoor air temperature. This ensures maximum system efficiency in real‐time while maintaining cooling requirements at the lowest total kW per ton.
• Geothermal Heat Pumps:  Also known as the ground source heat pump, this technology relies on the fact that the earth (beneath the surface) remains at a relatively constant temperature throughout the year, warmer than the air above it during the winter and cooler in the summer. The geothermal heat pump takes advantage of this by transferring heat stored in the earth or in ground water into a building during the winter and transferring it out of the building and back into the ground during the summer.

With more than 40% of CO2 emissions coming from buildings, and an average of 30% of  building’s energy being wasted annually,  focus needs to shift to the way buildings are being designed, built, operated and maintained. New advancements in technology, however, are making it easier to create net zero energy buildings which are not only more energy efficient and sustainable but can also produce renewable energy.

1. Make humidification adjustments

Generally speaking, IT equipment can tolerate wider ranges of humidity than previously thought. Until very recently, most data centers kept humidity between 45 and 50% relative humidity (RH).  The concern was that low humidity could lead to electrostatic discharge (ESD) failures, and that high humidity could cause water droplets to condense inside equipment.

However, improved humidity tolerances in equipment have resulted in ASHRAE relaxing its recommended humidity ranges. ASHRAE’s recommended data center humidity ranges are:

• Lower limit: 42 degrees F dew point
• Upper limit: 59 degree F dew point and 60% relative humidity (regardless of temperatures

2. Install In-rack or In-row Cooling:

In a room-based setup, computer room air conditioning (CRAC) units push chilled air into a data center and around the equipment to prevent sensitive electronic equipment from overheating.

With a row-oriented cooling architecture, or in-rack systems, each CRAC unit is dedicated to cooling one row of server racks. Compared with the room-based cooling, airflow paths are shorter, reducing the CRAC fan power required to send air to the equipment which vastly improves efficiency.

In-row and in-rack cooling systems can have higher capital costs than room-based cooling systems. However, row-based cooling systems use less electricity than across all server rack densities because the cooling units are located closer to the IT loads and unnecessary air flow is avoided. This can save more than 50% of fan power consumption compared with room-based cooling systems.

3. Utilize Instrumentation Sensors

Sensors for instrumentation (temperature, input power, utilization, air inlet temperatures, etc.)  help monitor the data center and spot problems that need to be addressed.  Furthermore, such environmental instrumentation can send alerts when safe operating temperatures are likely to be exceeded so that cooling loads can be adjusted in response.

Some equipment monitoring systems can provide remote monitoring and management of cooling units, making cooling adjustments automatically in response to these fluctuating heat loads.  This not only extends the life of plant equipment but dramatically lowers the cost of data center cooling.

4. Matching Cooling to Heat Load

The most efficient data center cooling systems provide just enough cooling to match the load, but this can be a major challenge because cooling units are sized for peak demand, which rarely occurs.  The challenge can be addressed, however, using intelligent cooling controls.  With appropriate instrumentation in place, these controls can monitor and quickly adjust cooling capacity and airflow based on actual conditions in the data center. tekWorx Xpress® data center solutions optimize plant cooling equipment by operating with actual data center conditions, not predicted conditions, with no downtime or disruption.