Investments in energy efficiency can involve substantial upfront costs, but they can also pay for themselves several times over. In some cases, they can even confer additional benefits that exceed savings from reduced energy use.
Honeywell recently completed a $2 million "smart building" retrofit project at the Spring Creek Towers complex in Brooklyn, New York. The complex has 46 buildings comprising 5,881 units, a recreation and shopping center, a central cogeneration plant that converts natural gas and fuel oil to high-pressure steam, and several secondary plants. It is not connected to the grid.
The project centered around installation of a building management system, which monitors energy facilities, and utility submeters, which give building managers insight into energy usage patterns, and how to make consumption more efficient.
“They can, in real time, measure the supply and return temperatures to the apartments and understand whether the system is doing its job efficiently,” according to Greg Turner, Vice President of Global Offerings for Honeywell Building Solutions.
Turner explained the importance of supply and return temperatures in assessing the efficiency of heating and cooling systems:
“The central plants provide a water loop (hot/cold) to the units in each building for local heating and cooling. We control and measure the ‘supply’ water temperature in that loop going into the units to provide water that is just warm enough or cold enough, based on outside air conditions, to allow the apartments to control their space temperature. We then measure the ‘return’ loop temperature of the water leaving the unit, after it has been used to heat or cool the space, to understand the thermal efficiency of the heat transfer in the building. By controlling the ‘supply’ loop temperature to only what is required for demand, we decrease the thermal loss substantially and thus save energy while maintaining comfort. By measuring the return, we can constantly monitor the efficiency of the local controls and equipment across the many different weather and load conditions.”
And since many of the buildings are identical, anomalies in energy usage are easier to identify, making potential problems -- and any necessary fixes -- easier to manage. “You can use energy-efficiency data to decide on capital improvements.”
Communication Is Key
One of the major hurdles to making the facility “smart” was an outdated communications system, according to Turner. “The original infrastructure was done over copper phone lines, so all of their original communications, and their alarm tracking, were aging to the point where on any given day, 30 percent of them didn’t work, and if it rained or the wind blew hard, none of them worked,” he said.
Effective and reliable communication is a necessary component of a building management system. “To have a smart grid, you have to have a smart building,” Turner said. “All the pieces have to talk to each other in order to get the building to optimum performance.”
The most cost-effective solution for upgrading the communications network was installation of a passive fiber-optic local area network, which has ultimately given the facility far more bandwidth than needed to run the energy system alone.
“Their energy project has, in effect, bought them a network that will do a bunch of other things for them,” said Turner. “They’ve got four fiber channels, of which the building management system is using barely one.” Additional bandwidth can be used for other tenant services, such as an improved security system.
The additional financial benefits from the new communications system are expected to far outweigh savings from reduced energy use. “They expect payback will be about one-third energy and two-thirds operational,” said Turner. Spring Creek Towers expects to recoup its investment in about three years.
And this helps to solve another major problem that can deter building owners from investing in energy efficiency. “Energy projects are necessary, but they’re sometimes hard to make exciting,” Turner said. “If the infrastructure we put in [for energy] can also give them the backbone for a security project, that’s kind of the bow on the package.”