Renewable Energy

The CCGT features three arrays of photovoltaic panels: rooftop panels covering 75% of the roof, building integrated photovoltaic window awnings on the south and west façades, and a solar berm at ground level. Peak electric energy output from the panels is 71 kW. Solar energy is expected to satisfy up to 70% of the building’s peak demand and up to 30% of annual energy consumption.

Energy Efficiency

The building incorporates a number of demand (lighting, cooling and heating) and energy consumption reduction measures, including:

• The building envelope uses high performance, insulated, spectrally selective low-e glazing with external shading to maximize daylighting and winter solar gain, while minimizing summer fenestration load.
• The rooftop garden provides a greater level of insulation and lowers roof surface temperature.
• Direct and Indirect light fixtures are fitted with electronic dimmable ballasts. These lights allow reduction of lighting density per square foot and, in combination with photometric sensors and occupancy sensors, reduce electrical energy consumption when natural lighting is available or when the space is unoccupied.
• A run-around heat recovery loop tied to the heat pump system recovers energy from exhaust air and uses that energy to preheat/cool incoming ventilation air, saving energy costs throughout the year.
• Extensive daylighting throughout reduces the need for artificial lighting, resulting in over 25% savings in lighting energy over standard systems.
• By optimizing the piping and ductwork sizing, these systems have been designed to minimize the brake horsepower of the HVAC system, thus obtaining maximum efficiency.
• A ground-source heat pump system, consisting of 28 vertical wells drilled to a depth of 200 feet, provides all space cooling and over 90% of the space heating. During the winter months, heat from the heat pumps is supplemented by heat from a natural gas-fired, high-efficiency condensing hot water boiler.
• Programmed to prevent demand spikes during periods of high electrical use, the Building Management System reads the load required and temporarily offsets mechanical and electrical lighting systems operations to save demand costs. Additionally, mechanical and electrical systems were commissioned to ensure they were installed and functioning per the original design intent at maximum efficiency.

Cost Effectiveness

As a result of these energy conservation measures, the building has a significant reduction in energy consumption: over 75% over typical office buildings in Chicago, and 45% over ASHRAE Standard 90.1 compliant buildings without PV credit and 60% over buildings with PV credit.

It also surpasses ASHRAE Standard 90.1, using 60% less energy than a minimally code-compliant building of the same size, saving an estimated $21,500 each year with PV credit, or $11,400 a year without PV credit. The increase of the mechanical and electrical construction costs was less than $60,000 in the overall budget, with simple payback in less than six years.

Indoor Air Quality

The heating, ventilating, and air-conditioning system exceeds the strict City of Chicago building codes for indoor air quality, as well as ASHRAE Standards 62 and 55.

The building is designed to take full advantage of natural ventilation with operable windows located throughout the facility and numerous through-the-wall exhaust fans, allowing users to ventilate the entire building at a high rate of air-changes when outdoor air temperature permits, and during pre-occupancy night purge cycles. Air distribution utilizes a displacement ventilation system with air to the offices delivered at or near floor level near each workstation. High efficiency filtration is utilized at the make-up air system.

Air quality was also maintained throughout construction with a construction indoor air quality management plan, which involves protecting ducts and equipment from contamination and cleaning ducts prior to occupancy, as well as bringing in filtered fresh air during construction and post-construction purge ventilation. No- and low-VOC materials were used exclusively in the construction of the building and all asbestos and other hazardous materials were removed during demolition. Smoking was, and is, not permitted inside the building.

The building was also fully commissioned to assure indoor air quality during construction and pre-occupancy, and continued with monitoring during the first year of occupancy. While no accurate statistical data on the level of thermal comfort and IAQ satisfaction is available, we have conducted an informal survey of employees, maintenance staff, management personnel and visitors with not a single complaint on any systems’ deficiencies.

During the Measurement and Verification process all parameters, including CO2, temperature and humidity have been confirmed to exceed ASHRAE 55 Standards.

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