Net-Zero Energy System
The CSL was designed to achieve net-zero energy status on an annual basis, meaning that, over the course of a year, it is expected to produce more energy than it consumes. In addition to generating power with a vertical axis wind turbine and photovoltaic solar panels, the CSL also takes advantage of geothermal wells, and passive cooling, heating and lighting methods, to operate more efficiently.
- Strategic window placement, light shelves that direct the sun’s rays and reflective ceiling material all allow for daylight to naturally illuminate the interior 80 percent of the time, reducing the need for energy-intensive artificial lighting.
- High performance insulation and low-e windows help keep heat inside during the winter and outside during the summer.
- Onsite photovoltaic solar panels, positioned and oriented based on several sun-tracking studies, are expected to generate enough electricity to meet energy needs on an annual basis.
- A vertical axis wind turbine, the first to be commissioned in the City of Pittsburgh, can produce energy with winds as low as 4.25 mph.
- A series of geothermal wells buried 500 feet below ground are used to capture heating and cooling energy from the earth’s consistent 55-degree temperature.
- Working in conjunction with the geothermal wells, a Rooftop Energy Recovery Unit is expected to reduce HVAC energy requirements by 40 percent.
Design and Building Systems
The 21,892 sf building is designed to serve as an office, classroom, research, and library space for the Conservatory. The general purpose of the building is educational and demonstrational, as well as to provide work space for employees and volunteers. The building consists of two main regularly occupied floors with a third, non‐occupied, floor in the atrium. The exterior of the atrium is constructed mostly of glass, allowing for an interior greenhouse that can support plant life in a minimally tempered interior environment. The rest of the building is constructed so as to ensure optimum energy performance in the tempered spaces.
The building is concrete and steel construction with a wood façade and metal frame windows. The glazing is high performance, low‐E, double pane windows, that in some locations, are operable. A green roof has also been installed to reduce heat island effect and impervious coverage, while at the same time providing an excellent thermal barrier between conditioned and non‐conditioned spaces.
Mechanically, the building is primarily served by an under floor air distribution (UFAD) system. UFAD was selected because of its efficiency and low energy consumption relative to comparable systems. The UFAD provides optimum comfort control while at the same time preventing over ventilation by reducing ventilation to unoccupied air volumes. The UFAD system introduced ventilation air directly into the breathing zone and allows heat from internal loads to stratify above the occupants. When outside air conditions permit, the building is cooled by natural ventilation through motorized operable windows and full economizing cycle on the rooftop unit. The atrium is not mechanically conditioned. HEPEX Tubing for a future radiant hydronic heating system is installed to temper the space in the heating season (if this proves to be necessary), and no cooling is provided to the atrium in the cooling season. Instead, the atrium relies totally on natural ventilation. Computational Fluid Dynamics (CFD) models of the atrium were created to evaluate feasibility and practicality.
The entire system is served by a roof top air handling unit (AHU‐1). One dedicated rooftop unit serves the under floor system for the entire building. The unit consists of a filter module (MERV 9 pre‐filters and MERV 13 final filters), recirc/mixing box module, exhaust fan with VFD, enthalpy wheel module, tricoil module, supply fan with VFD and water cooled compressors. The unit provides approximate 12,000 cfm supply air with the ability to go to a full economizer cycle when outdoor air conditions allow. The unit responds to CO2 demand control ventilation. The tri‐coil design includes a DX coil sandwiched in between a glycol run around loop. The run around loop and associated fractional horsepower pump provides pre‐cooling and reheating to increase dehumidification capacity. The desiccant coated total enthalpy recovery wheel provides free heating, cooling, dehumidification and/or humidification depending on the season. The system capacity is based on loads and ventilation requirements as calculated using Trane Trace 700 software program. All occupied spaces are ventilated with outdoor air (OA) in accordance with ASHRAE 62.1‐2004 with the intent of meeting LEED Indoor Environmental Quality Prerequisite 1, Minimum IAQ Performance and Credit 2, Increased Ventilation. Thermal comfort conditions comply with ASHRAE Standard 55‐2004 within all mechanically ventilated spaces.
A geothermal well system has also been installed as part of the energy conservation measures. The wells are 510 feet deep and twenty feet on center from well to well. These wells feed water cooled compressors for both heating and cooling loads by providing tempered water to the AHU in the winter and cool water during the summer. All HVAC equipment is controlled via a direct digital control (DDC) building automation system (BAS), and all metering pertaining to HVAC work records data in conjunction with the BAS.
Monitoring Methods: Solar PV monitoring at the Phipps CSL was conducted using an EMON Metering system for the first three months of the year until the Sunny Boy Portal, a web-based monitoring tool came online in April. The Sunny Boy Portal system is online and can be accessed remotely on the web and has applications for smart phones.
- Achieved the International Living Future Institute’s Living Building Challenge certification, the highest performance standard for sustainable building practices, in March 2015
- Achieved Living Building Challenge Net Zero Energy Building Certification in February 2014
- LEED® Platinum certified with a score of 63 out of 69 points for a new construction under version 2.2; only one other new building has achieved this level of green building distinction
- In first operational year, achieved with a 68.7% reduction of energy usage versus traditionally-designed buildings per EPA’s Target Finder
- Designed to reduce capacity requirements for HVAC systems and associated infrastructure (power, pipes, ductwork, pumps, etc.) by 30-40%