Firm name: Peter Basso Associates Inc.
Project building name and location: Eastern Michigan University Mark Jefferson Science Complex, Ypsilanti, Michigan
Type of building and type of project: Research and teaching labs, New Construction and Renovation
Project completion date and project duration: August 2012
Engineering challenges and solutions:
- Maintaining occupancy and the ability to continue teaching and research activities during the construction period was a key concern of the University Registrar’s Office and faculty.
- Providing a safe environment for the researchers and students with respect to indoor air quality was a key concern of University Occupational Health and Safety personnel. Reducing energy consumption was a key concern of the University’s Energy Engineer.
- Providing reliable systems with reduced maintenance and operating costs was a key concern of the University’s Plant Operations group.
New mechanical and electrical spaces, which were designed to serve the addition and renovation, were located in the basement of the new addition. New duct, piping, and electrical shafts were located between the existing building and the new addition and were prepped to serve either side. The new systems were designed such that they could be ramped-up to serve the spaces as they were brought on-line. The addition was completed and brought on-line first. Researchers and faculty were moved into the addition and vacated floors basement through second in the existing building. The existing mechanical systems were located in the penthouse of the existing building, and were simply ‘pealed back’ to allow renovation of the first three floors. These three floors were then fed from the new systems which were ramped up to handle the new loads. As these spaces are occupied the top four floors will be vacated and renovated. As a result, minimal disruption to the occupants occurred.
Laboratory buildings are notorious energy consumers – up to 10 times that of a typical office building. This is a result of conventional lab systems requiring high quantities of outdoor air which needs to be heated and humidified in the winter and cooled and dehumidified then reheated in the summer. These outdoor air quantities are required to satisfy minimum air change rates and make-up air requirements for fume hoods. This outdoor air is typically heated to 55 in the winter and humidified, and cooled to 52 degrees or so for dehumidification in the summer, and then is reheated with hot water to avoid overcooling spaces. Large quantities of outdoor air have also typically been provided to handle the cooling of spaces with high internal heat loads.
For this building, a non-conventional HVAC system was provided which 1) provides neutral temperature outdoor air to meet minimum air change rates and fume hood make-up requirements, and 2) provides cooling on a room by room basis with terminal equipment. This system de-couples the ventilation and the heating/cooling functions of an HVAC system and treats each in a very efficient manner. The ventilation is provided by a dedicated outdoor air system (DOAS) which includes dual energy recovery. This system recovers energy from the exhaust air stream and transfers that energy to the incoming outdoor air, reducing the heating and cooling loads of the outdoor air. This system also transfers heat from the upstream side of the cooling coil to the downstream side, providing neutral temperature supply air without reheat whenever possible. The heat recovery equipment provided was heat pipe type, which has no moving parts and no maintenance requirements.
The outdoor air energy recovery coil was provided with by-pass dampers to allow economizer operation, and the cooling coil with wrap around heat pipe is provided with by-pass dampers to reduce system static pressure whenever cooling/dehumidification is not required. Occupancy sensors were provided to turn off lights and to reduce air change rates during un-occupied periods. Spaces are then heated and cooled on a room by room basis with active chilled beams. Chilled water or hot water is only utilized when required based on zone temperature demand. All of the major energy consuming equipment – air handling units, laboratory exhaust fans, chiller – were pre-purchased. This equipment was specified to exceed ASHRAE 90.1 requirements where applicable.
Manufacturers were then engaged and asked to submit equipment as scheduled, and more or less efficient/more or less expensive options. The Owner was then able to make equipment selections based upon a life cycle cost analysis of each piece of equipment, based upon an assumed load profile that was prepared. In each case, a slightly more expensive unit was selected which had a very short payback period. 3. This mechanical system, although somewhat unconventional in configuration and function, consists of mainly conventional, proven components with minimal maintenance requirements beyond a conventional system. Chilled beams have no moving parts and operate with a dry coil and so will typically not require cleaning. Heat pipe energy recovery coils do not have moving parts or maintenance requirements. Laboratory airflow controls utilized are mostly two-position valves as they are only satisfying the ventilation function of the spaces, significantly simplifying their operation and maintenance (and significantly reducing their first cost).
The temperature control system is a micro-processor based building automation system utilizing direct digital controls which monitors, controls, and optimizes the operation of the HVAC system. DDC panels are networked together and connected to the existing campus building automation system and are web enabled for easy access from off-site. The entire system was functionally tested to ‘get the bugs out’, and Owner training was provided so that the Owner had a thorough understanding of the system’s operation prior to the University taking ownership. This ‘modern’ laboratory system is the first such system installed and operating in Michigan.
It is estimated that approximately $1,000,000 in first cost savings was realized over a conventional VAV reheat system due to reductions in air handling equipment, controls, ductwork, heating and cooling plant infrastructure, mechanical room/shaft footprint, etc. Based upon the energy model that was prepared, this system will save 49% on energy consumption over an ASHRAE 90.1, 2007 compliant system.