(Key Words) Green-Building LEED-NC HVAC&R DEP Energy-Star
The first United States Green Building Council LEED-NC (Leadership in Environmental Efficiency Design - New Construction) certified Green Building in West Virginia (WV) is the state Department of Environmental Protection (DEP) headquarters building. The LEED-NC Green Building certification is the widely accepted benchmark for the design, construction, and operation of high performance green buildings. The LEED system is based on a whole building approach to sustainability, and recognizes leadership and innovation in design and construction of buildings with reduced environmental impacts.
Figure 1 – West Virginia Dept. of Environmental Protection Building
Rigney Digital Systems of Hurricane, West Virginia (WV), an ASI Controls Value-Added Reseller, was invited early in this project to help specify, design, and configure the complete HVAC control system for the new building. Operating an efficient, integrated HVAC system is crucial to attaining Green Building status, as the HVAC system performance can drive as much as one-third of the total LEED score for a building. To attain Green Building certification one can not simply install high efficiency equipment. The West Virginia DEP building integrates new technologies, construction methods and control strategies that together deliver climate control and occupant comfort while minimizing energy consumption. Designing, configuring, installing and operating these new technologies and sub-systems within the context of the LEED-NC scoring system adds complexities and challenges to the project.
The West Virginia DEP set a goal of attaining Green Building certification; the challenge was to get the LEED rating within the constraints of a limited budget. Work on the mechanical specifications started well in advance of construction, in coordination with engineering consultant Nadeem Khan P.E., of Advanced Facility Design. Leveraging the powerful family of ASIC/2 configurable controllers to perform complex calculations and command the networks of terminal unit controllers, Paul Rigney of Rigney Digital Systems helped to specify an HVAC system that received a high LEED credit score while also performing from a cost, maintenance and management perspective.
Figure 2 – twin ASIC/2 configurable controllers command each of the two custom Mammoth penthouse air-conditioning units
The Mammoth, Inc. custom-built rooftop air conditioning system generates over 400 tons of cooling. Two ASI Controls ASIC-2/7040 controllers were pre-installed in each of the two custom penthouse air conditioning units at the Mammoth factory. An additional ASIC-2/7040 is used to control the boilers, and to modulate the hot water pumps. Demand-based ventilation is based on CO2 monitoring.
Within the cooling system, the control system modulates the three screw compressors, and monitors the evaporative condensers. Head pressure control is achieved through the use of variable frequency drives controlling the condenser fans to maintain sump water temperature at setpoint. Evaporative cooling, which uses the latent heat of evaporation of water rather than the sensible heat transfer of dry cooling, is a fundamentally more efficient process than dry cooling. The higher transfer efficiency enables smaller overall sizing and lower volume requirements for the fans, factors which add to the energy efficiency gains of wet cooling.
The expected efficiency gains of evaporative cooling are a factor of the difference between ambient wet bulb temperature and dry bulb temperature. In most cases the evaporative cooling system consumes about 20-40% less energy and 20-50% less peak demand to maintain the same supply temperature in a low to moderate ambient humidity environment than an equivalent dry cooling system. In addition, evaporative cooling generally offers lower maintenance requirements and more consistent system performance than dry cooling. In areas with prevailing high humidity the difference between web bulb and dry bulb temperatures is narrow, which lowers the expected energy and demand savings from wet cooling versus dry cooling.
Figure 4 –ASIC/2 controller manages boilers and hot water pumps
Each of the dual supply and return fans has a capacity of 72,300 CFM at 4" wc. Thirteen ASIC-2/8040's were used in the facility to manage sub-networks of terminal controllers. A total of 520 ASIC-1/8055's, each with accompanying WS-031 wall sensors, were installed to control individual VAV boxes.
Rigney Digital Systems is also responsible for lighting control in the building. RDS used an ASIC/2-8040 configurable controller to manage each of two lighting zones per floor. The lighting schedule is integrated to the building occupancy schedule, with pushbutton overrides available for users on individual wall mounted thermostats. The pushbutton override functionality enables the building to conserve energy by running a tight occupancy schedule without limiting the ability of building users to utilize their offices early or late in the day, or on weekends.
RDS appreciated the processing power provided by the ASIC/2-7040 at the controller level. They were able to configure the controllers to handle complex realtime airflow and CO2 requirements without needing to offload calculations to a supervisory controller or the central unit.
Figure 5 – Ultrasonic Nebulizers in the supply air tunnelRigney Digital Systems is also responsible for lighting control in the building. RDS used an ASIC/2-8040 configurable controller to manage each of two lighting zones per floor. The lighting schedule is integrated to the building occupancy schedule, with pushbutton overrides available for users on individual wall mounted thermostats. The pushbutton override functionality enables the building to conserve energy by running a tight occupancy schedule without limiting the ability of building users to utilize their offices early or late in the day, or on weekends.
RDS appreciated the processing power provided by the ASIC/2-7040 at the controller level. They were able to configure the controllers to handle complex realtime airflow and CO2 requirements without needing to offload calculations to a supervisory controller or the central unit.
Relative humidity is adjusted using ultrasonic technology rather than traditional energy-intensive electric or mechanical heating. A small piezoelectric ceramic disc is modulated at ultra-high frequencies to produce water vapor that is added to the ventilation stream. Ultrosonic humidification is the only technology able to produce droplets as small as those produced by boiling water, but ultrasonic humidification technology requires over 90% less energy than conventional steam humidification. Other benefits of ultrasonic humidification technology include a free cooling effect in many ambient conditions (about 1,000 BTU/pound of water evaporated), low maintenance, and a fine degree of control. Water treatment sufficient to reduce particulates to 2.5 ppm or less needs to be factored into overall cost when applying ultrasonic humidification.
An ASI WebLink user interface was installed to display building control system information for authorized personnel. With WebLink, the building control system can be accessed from any browser on the Internet, with password-protected logins. WebLink enables local or remote monitoring of system status, electrical demand, CO2 concentrations and other metrics, and supports graphing and reporting on any trended data. The integrated trending and alarming capabilities enable extensive monitoring of conditions, with automated forwarding of alarm and event notifications to email, cell phone or pager if the system requires intervention.
An ASI WebLink user interface was installed to display building control system information for authorized personnel. With WebLink, the building control system can be accessed from any browser on the Internet, with password-protected logins. WebLink enables local or remote monitoring of system status, electrical demand, CO2 concentrations and other metrics, and supports graphing and reporting on any trended data. The integrated trending and alarming capabilities enable extensive monitoring of conditions, with automated forwarding of alarm and event notifications to email, cell phone or pager if the system requires intervention.
The WV-DEP building is also an Energy Star-rated building. The United States Environmental Protection Agency’s Energy Star program provides the Energy Star rating to buildings in the top 25% of their class on an energy efficiency basis. The building classifications are based on characteristics including type, age, and function.
While the number of LEED-NC certified Green Buildings remains small compared to the total market, the cost and performance differences of an HVAC system designed for a Green Building as compared to a regular building are much smaller today than they were when DDC first entered the HVAC market. Use of new technologies, processes and practices in LEED Green Buildings can provide the HVAC industry with measures of performance, applicability and suitability for other building environments. Experience and practice will help bring new technologies, processes and practices into mainstream use*. ASI Controls is dedicated to providing hardware and software that enables value-added resellers to deliver cost-effective solutions for all types of digital control requirements.
* In the US, the National Energy Policy Act of 2005 Commercial Building Tax Incentives may significantly reduce the final cost for digital control systems and equipment that deliver high building energy efficiency through integrated energy management.
Table of Figures
Figure 1 – West Virginia Dept. of Environmental Protection Building 1
Figure 2 – twin ASIC/2 configurable controllers command each of the
two custom Mammoth penthouse air-conditioning units 2
Figure 3 – explanation of evaporative condensing (image copyright Mammoth Inc.)3
Figure 4 –ASIC/2 controller manages boilers and hot water pumps 3
Figure 5 – Ultrasonic Nebulizers in the supply air tunnel 4
Figure 6 – example WebLink browser screens 5
