Heat pump-based HVAC and control system contributes to bright IdeA(s)
The new headquarters of Integrated Design Associates (IDeAs) Inc. is a testament to the company’s commitment to helping architects design the best and most energy efficient buildings. The new IDeAs headquarters is the first commercial office building in the U.S. designed to meet a net-zero energy/net-zero carbon emissions goal.
Johnson Controls designed and installed a unique heat pump-based HVAC and control system, which is a key contributor to minimizing the building’s energy consumption. IDeAs is a consultancy that provides electrical engineering and lighting design services for projects such as educational and medical facilities, office and retail spaces, and restaurants and apartments. When the company bought a 7,200-sq-ft former bank branch to house its new headquarters, David Kaneda, principal, saw an opportunity to bring the concept of a zero-energy building to life.
The goal was to transform a 1960s-era windowless concrete bank into a highly efficient and comfortable building using a full complement of sustainable design techniques and technologies. The result is an office building that uses renewable energy from photovoltaics to meet 100% of its energy requirements, burns no fossil fuels, and produces no net greenhouse gas emissions.
Maximizing Efficiency, Minimizing CostsJohnson Controls designed the HVAC system to maximize performance, energy efficiency, and IAQ, while keeping the construction costs comparable to more traditional designs. The energy efficiency for the HVAC system and building envelope is estimated to be 40% below the 2005 California Title 24 energy requirements.
The design incorporates a geothermal heat pump, which takes advantage of the fact that the temperature below ground remains constant all year round - about 10°C in this case. Water flows through pipes laid under an open landscape area and passes into the building, where a heat exchanger collects the heat from the water in the winter and uses the cooling effect of the water in the summer. A radiant floor system with cross-linked, counterflow tubing uses the water to convey heating and cooling to the space.
The system uses less energy to provide the same level of comfort as traditional systems, due to the temperature variance between the occupants and the floor itself. “Since the system has been operating it has already provided a very cool and comfortable environment during some very hot weather,” said Kaneda. “It is a very efficient system that will help us meet our net zero energy target.”
A Johnson Controls Metasys‚ BMS controls the flow rates and slab temperature to provide the maximum performance using the least amount of energy. Pump speeds are kept at their lowest demand speed using power inverter technology that responds to actual demand. Floor condensation is monitored and dehumidification provided, if needed, with an air-handling system that also uses the water from the geothermal system. The Metasys system also monitors air quality sensors and automatically operates the air handler when CO2 levels rise above a preset point.
Net-Zero DesignA building integrated photovoltaic system is the facility’s energy source. The panels in this system are part of the single-ply membrane roof installed on the facility. The electrical system is tied into the grid, so it will draw power at night when there is no sunlight and deliver power back to the grid when more energy is generated than is being used during the day. The result is designed to be “net-zero” in overall energy use.
Kaneda’s team added windows and skylights and high-efficiency windows. An overhang shades south-facing windows and those facing east incorporate electrochromic window glazing that is controlled by a sensor that darkens the windows when the sun hits them directly. Used throughout the building, low-energy fluorescent bulbs are either controlled by occupancy sensors, or use dimming ballasts, and light sensors turn off select fixtures when daylighting is sufficient.
Energy conservation extends to computers and office equipment as well. LCD flat-screens take the place of traditional monitors, which use 50% more power, and laptops replace desktop computers where possible. The design team integrated office equipment with the building security system, automatically shutting the equipment down when the security system is armed – and restoring power when the system is disarmed.
“All of the technologies we are using are readily available. Some of them are more expensive from a first-cost standpoint, but the reduction in energy use will pay long term dividends,” said Kaneda. “And, it’s the right thing to do from the standpoint of reducing our impact on the environment.” ES