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Multifamily Energy Savings: Five Questions to Ask

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Looking to reduce costs and enhance the value of your properties? Energy efficiency upgrades can help you do both. Energy costs are a big budget item and slick new devices, such as LED lights and smart thermostats, are appealing to potential tenants. If you’re looking to save energy, begin by asking yourself these questions:

1. Are there fluorescent lamps or incandescent bulbs in common areas?

Cost-effective LED replacement options are available. LEDs are highly efficient and last much longer than conventional lights. LEDs also offer improved light quality, enhancing safety and visual appeal.

2. Do you frequently find lights on in empty spaces?

Even high efficiency lights still waste energy illuminating empty spaces. Occupancy or vacancy sensors can solve this problem by automatically turning lights on and off based on need. They’re especially effective in common areas with varying occupancy, such as restrooms, fitness rooms and laundry facilities.

3. Are hot water pipes properly insulated?

Water heating accounts for 18% of energy costs in multifamily buildings, and much of that goes to waste through unwanted heat loss. Pipe insulation is a simple and cost-effective measure for reducing energy loss and saving money.

4. Are water leaks fixed in a timely manner?

Water leaks can waste a significant amount of water and energy for water heating. For example, a showerhead leaking at 10 drips per minute wastes more than 500 gallons a year. Regularly inspect for leaks  and fix them quickly. While you’re at it, install water-efficient showerheads and faucet aerators. They’ll save water while still providing a comfortable flow.

5. Are Wi-Fi enabled thermostats installed throughout your building?

Adjusting building temperatures is the simplest and most effective way to reduce energy costs. WiFi-enabled programmable thermostats add convenience and optimize savings. They also offer advanced features, such as remote control.

Buying In: Investing in Energy Efficiency

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Commercial and residential buildings account for nearly 40% of the energy consumed in the United States. All available cost-effective, energy efficiency improvements would require roughly $279 billion in investments, resulting in more than $1 trillion in energy savings over 10 years. However, currently only 1% of all U.S. investment dollars are directed toward energy efficiency projects.

The reluctance to invest in such projects is driven by the lack of predictability in long-term returns, as well as the lack of standardization in the energy efficiency market. To address these issues, the Environmental Defense Fund (EDF) established the Investor Confidence Project (ICP).

Setting standards

The ICP developed ways to measure and predict energy savings so that investors are more willing to finance energy efficiency projects. The project recently introduced several energy performance protocols which standardize how projects are baselined, engineered, installed, operated and measured:

  • Large Commercial, for whole building (more than 150,000 square feet) retrofits greater than $1 million, with annual energy savings of more than 20%.
  • Standard Commercial, for whole building (up to 500,000 square feet) retrofits priced below $1 million. Projected savings cover investment cost.
  • Targeted Commercial, for upgrades involving a single measure, such as lighting or windows, or multiple measures costing less than $1 million and in buildings up to 500,000 square feet.
  • Large Multifamily, for whole building (up to 500,000 square feet) retrofits costing more than $1 million. Projected savings cover investment cost.
  • Standard Multifamily, for whole building (up to 500,000 square feet) retrofits costing less than $1 million. Projected savings cover investment cost.
  • Targeted Multifamily, for single or multiple measure projects costing under $200,000 in buildings up to 500,000 square feet.

Accelerating investment

Targeted protocols strike a balance between the need to minimize overhead for less complex projects while maintaining the necessary rigor to attract investment for smaller projects. All protocols are aimed at boosting investor confidence in the resulting savings and return-on-investment.

The EDF also developed a Quality Assurance Credential, which authorizes third-party providers to verify a project conforms to ICP protocols and certify it as an Investor Ready Energy Efficiency project. For investors, standardized projects and documentation enable efficient due diligence, faster underwriting and more reliable returns.

To overcome the small quantity and low quality of data available for evaluating investments in energy efficiency assets, the EDF’s Energy and Loan Performance Data Project collected and analyzed data about loan performance and energy savings from efficiency upgrades. With better data, loan performance is more easily and accurately predicted, making large-scale investment in building retrofits more attractive.

Improve Chiller Performance with VSDs

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Chiller system motors and fans are often too big for the job. Larger motors are typically more efficient, but they may waste a significant amount of energy if they frequently operate at less than their rated capacity. Variable speed drives (VSDs) save energy by reducing fan and motor speed to match the lower or varying demand.

VSDs and chiller systems

Motor power consumption is proportional to the cube of motor speed; a decrease in speed leads to a larger decrease in energy use. For example, a 20% reduction in speed will yield roughly 45% in energy savings.

VSDs can help reduce the energy use of four major chiller components:

  1. Compressor motors (refrigerant loops)
  2. Pumps (water loops)
  3. Cooling tower fans
  4. Air handling unit fan motors

The application of VSDs typically reduces a chiller’s annual energy consumption by up to 30%, according to Johnson Controls. The savings can be much higher, depending on the type of facility and equipment.

By reducing the rotational speed of a compressor motor in response to off-peak, low-load conditions, VSDs can reduce the energy use of chillers. For water-cooled chillers, the use of VSDs can also reduce pump energy use. Especially at low loads, both types of VSD chillers can operate using significantly less energy.

Many manufacturers offer VSD-driven chillers as an option. Most existing chillers can also be modified unless the manufacturer doesn’t offer a VSD retrofit kit.

The many benefits of VSDs

The advantages of installing VSDs go beyond energy savings. Additional benefits include:

  • Less stress and wear on fans and motors, improving their service life
  • Reduction in the number of chillers and related equipment
  • Decreased chilled water pumping costs
  • Minimize damage to sensitive electrical equipment (less electrical current on startup)
  • Reduction in size and cost of emergency generators (soft start capabilities)

As changes in the weather affect the temperature of the condenser water supply, VSDs will adjust chiller performance to compensate for variations in the compressor load.

VSDs can provide a good return on investment, especially in areas with high electricity rates. If your facility is charged for low power factor, VSDs can save you money by improving your power factor rating. Applying VSDs to induction motors can also help increase their power factor.

VSDs take a “byte” out of energy costs at data center

At a 100,000 square-foot data center, VSDs were installed on all mechanical cooling pumps, chilled water pumps and data floor air-handling units. As a result, fan speeds decreased by an average of 42%. At a total installation cost of about $45,000, the VSDs resulted in an annual savings of 385,000 kWh or more than $42,000 for a payback slightly  over one year.

Optimizing Operations: Chiller Energy Savings

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Chillers provide crucial cooling for air conditioning and refrigeration, but they use a lot of energy. If you’re looking to reduce your chiller energy costs, start with these low-cost operational strategies to improve system efficiency and performance.

1. Use controls to sequence chillers

Chillers rarely operate at full capacity, and their efficiency drops as the load decreases. An ideal capacity for maximum chiller efficiency is between 60% and 80%. Efficiency drops significantly at loads below 50%. Monitor the capacity of all chillers in the plant and switch them on or off to keep them operating in their most efficient zone.

2. Go with a variable flow

Many legacy chiller systems are designed using a constant primary flow arrangement, which uses constant speed pumps in front of the chiller. A three-way valve is placed on the discharge of each coil to maintain the set-point temperature of the air leaving the coil. Changing to a variable primary flow design using two-way valves can reduce energy consumption by 50% to 75%.

3. Manage water temperature

An often-overlooked method for improving chiller efficiency is managing water temperature. We’ll look at three strategies — delta T, approach temperature and chiller lift.

  • Delta T is the temperature difference between the chilled water supply and chilled water return. A low delta T forces chilled water pumps to work harder than necessary to produce the needed cooling.
  • Condenser and evaporator approach temperatures are important metrics that can impact chiller efficiency. Low approach temperatures indicate good heat flow between water and refrigerant.
  • Chiller lift is the temperature difference between the outgoing condensing and evaporator water. It represents the energy balance between the cooling tower fan and compressor operation. A lower lift is better.

Use an energy management system to monitor and evaluate these metrics and operate chillers at the optimum efficiency for every load condition.

Preventive maintenance pays off

The following preventive maintenance activities will keep your chiller system operating at peak performance:

  • Record refrigerant temperature and pressure, as well as water loop temperature daily.
  • Inspect the entire system on a scheduled basis, following the manufacturer’s recommendations.
  • Regularly check for problems such as refrigeration leaks, tube corrosion, sticking dampers and worn seals.
  • Check compressor operating pressures and analyze compressor oil annually.
  • Examine all motor terminals and monitor amperage draws.

Calibrate the temperature and pressure gauges and the water flow meters regularly to ensure accuracy. It’s also important to monitor and control the evaporator and condenser temperature and water flow rate.

By combining low-cost operational strategies with targeted maintenance measures, you can improve chiller system performance and save money without a big financial investment.