Energy efficiency measures for buildings tend to focus on lighting and HVAC systems. However, the energy consumption of hydraulic installations is often overlooked. Water supplies can get very cold in many parts of the world and a heating system is needed to reach a safe temperature. There may also be a pumping cost associated with water consumption, especially in tall buildings.
Traditionally, MEP design has been managed in isolation – building systems are designed separately and then coordinated. However, an integrated approach can achieve better design, as interactions between building systems are considered from the beginning. Plumbing systems can be designed to reduce water pumping and heating costs, and annual savings can reach thousands of dollars in large buildings.
Save on water and energy bills with a professional plumbing project.
Below, we will discuss some ways to reduce energy costs associated with a building's plumbing system.
How to Reduce Your Water Pumping Costs
Single-family homes and low-rise buildings do not experience water pressure problems under normal conditions, as the local utility maintains adequate pressure. However, tall buildings will normally need their own pumping system to supply water to the upper floors. As pumping systems consume electricity, there is an additional energy cost when it comes to low-rise construction.
There are two main strategies for reducing the operating cost of water pumping systems in buildings:
- Directly reducing water consumption (fewer gallons to pump).
- Using high efficiency pump motors (less electricity per gallon pumped).
Efficient plumbing installations can greatly reduce water consumption – installations with the US EPA WaterSense Label offer verified savings of at least 20% over federal standards. Plumbing fixtures can only achieve the WaterSense label if they have been successfully tested by an approved laboratory independent of the manufacturers.
Keep in mind that water conservation not only depends on the fixtures used, but also on the consumption habits of your building. Even if your entire plumbing system uses WaterSense fittings, it is very important to promote water conservation among occupants. In any building where water needs to be pumped, every gallon saved also results in electricity savings.
Water pumping costs can also be leveraged by using high-efficiency motors to drive the pumps. We recommend electric motors with NEMA Premium Efficiency or better. If your pumping system often operates at partial capacity, you can use a variable frequency drive (VFD) to reduce motor speed and save even more electricity. The combination of water-saving equipment and efficient motors will minimize pumping costs in high-rise buildings or any other properties that rely on pumps for their water supply.
How to Reduce Your Water Heating Costs
In cold climates, a water heating system is required by law – necessary for health and comfort. For example, New York requires that all buildings have a year-round hot water supply with a temperature of at least 120°F. The Department of Housing Preservation and Development frequently receives complaints about low water temperatures, and building owners should ensure their water heaters are working properly.
There are two main ways to reduce the energy cost associated with hot water systems:
- Directly reducing water consumption (fewer gallons to heat).
- Using an efficient water heater (less energy per gallon heated).
As with pumping costs, water conservation saves on heating simply because fewer gallons go through the water heater. This means that WaterSense appliances also save on heating – if your building uses 20% less water, you can expect your water heating costs to drop by a similar percentage.
When comparing water heaters, you can look for an efficiency metric called power factor. In simple words, power factor is the ratio of heat production to energy input. For example, a gas heater with an EF of 0.80 consumes 100 BTU of natural gas to provide 80 BTU of water heating. To make sure you get a high EF, you can look for ENERGY STAR Water Heaters :
|
Type of water heater |
Minimum EF for ENERGY STAR label |
|
Electric Heat Pump with Storage |
2.00 EF up to 55 gallons, 2.20 EF for larger heaters |
|
Gas heater with storage |
0.67 EF up to 55 gallons, 0.77 EF for larger heaters |
|
Tankless Gas Heater |
0.90 FE |
Keep in mind that the operating costs of a water heater will depend on three factors: workload, energy factor and local energy prices. In other words, comparing only efficiency values can lead to incorrect conclusions.
