Active Chilled Beams Come of Age
Case Study
Fraunhofer
Fraunhofer's Building Technology Showcase (BTS) represents the bright future of sustainable design in North America. Fraunhofer Center for Sustainable Energy Systems (CSE) is an applied research and development laboratory that provides R&D and related services for industry and government clients. The BTS is Fraunhofer CSE's headquarters in Boston's fast-growing Innovation District, a deep energy retrofit of a 100-year-old building that serves as a living laboratory for R&D of advanced sustainable energy technologies.
Completed in 2013, the BTS leverages cutting-edge materials and equipment in an effort to facilitate the nationwide adoption of energy-saving technologies. In response to Fraunhofer's challenge to showcase as much innovative technology as possible, the HVAC manufacturer worked with the project design team, DiMilla Shaffer Architects and BR+A Consulting Engineers to evaluate each area and apply a wide range of product, tailored to suit the needs of the space. One example of this is the mechanical system used in the main conference room. This system uses an innovative chilled beam which offers all of the discussed benefits of chilled beam systems, with the additional benefits of displacement ventilation.
Photo courtesy of Price Industries
Chilled beam system coupled with displacement ventilation.
In a displacement ventilation system, cool air is supplied at low velocity and at low level. This allows the cool air to pool at floor level where it is drawn into air currents knows as “thermal plumes” which form around heat sources in the room. These could include occupants, equipment or warm perimeter surfaces. In this way, the cooling air is only supplied to areas in the room where cooling is required, and fresh air is only delivered to occupants as they need it. As this cool air passes over the heat loads, it rises through the occupied zone and up into the area above occupants' heads. Here, the air picks up more heat from lighting, conduction through the exterior walls and is trapped up near the ceiling. In this way, displacement ventilation systems generally only supply enough cooling to meet the loads in first six feet in the room.
The key advantage of coupling a chilled beam system with displacement ventilation-style air pattern can be seen in the figures below. The first figure shows a typical displacement air pattern with supply at low level, warming through the room and returned from high level. This return air is considerably warmer than the room setpoint which is then cooled at the air handling unit. It is important to note that, even though the system only supplies enough cooling to meet the load in the occupied zone, it must still cool the entire room (building) load. The combination chilled beam—displacement ventilation system, in contrast, draws return air in the occupied zone so the air delivered from the air handling unit is only the minimum required to supply fresh air to the occupants. This puts most of the occupied zone on the more efficient water system. The heat loads in the area above occupants' heads is then exhausted from the room and rejected outside the building. This means that the heat picked up after it passes through the occupied zone is not cooled by the mechanical system. The amazing result is that this system has the capability of actually reducing the amount of cooling delivered by the air handlers and chillers. Not only does this mean energy savings vs. the baseline system because there is less cooling, but could also mean less equipment in the first place which would lead to lower first cost.
This product is generally located along the perimeter below windows, but could be located on any interior wall as well. The casing front must have some free area to allow air movement, with either perforated holes or a louvered style panel. It is not uncommon for these to also feature a controls cabinet that is the same size as the beam, thereby allowing easy access for the maintenance team, while having them located in a tidy cabinet that matches the look of the beams themselves. When these are located in school classrooms, one of the largest markets for this style of beam, it is also common to fill in the spaces between the beams (running the full length of the room is not often required) with matching book cases, thereby offering storage on top and between the units.
Images courtesy of Price Industries
The figure on the top shows a displacement ventilation system and the figure on the bottom, a chilled beam system.
This product is generally located along the perimeter below windows, but could be located on any interior wall as well. The casing front must have some free area to allow air movement, with either perforated holes or a louvered style panel. It is not uncommon for these to also feature a controls cabinet that is the same size as the beam, thereby allowing easy access for the maintenance team, while having them located in a tidy cabinet that matches the look of the beams themselves. When these are located in school classrooms, one of the largest markets for this style of beam, it is also common to fill in the spaces between the beams (running the full length of the room is not often required) with matching book cases, thereby offering storage on top and between the units.
Chilled Beams for Energy Efficiency
The chilled beam is an efficient solution optimally poised to help designers meet new energy standards. Chilled beams have the potential to deliver significant energy savings in nearly all building types, while allowing the designer considerable flexibility in placement and an aesthetic that is consistent with the vision of contemporary architecture in high end commercial and institutional settings. With proper analysis of building envelope, HVAC systems, condensation potential and available ceiling space, the architect can determine how much potential the application of an air-water, or active chilled beam system has for a building occupancy type. As our energy codes continue to evolve, HVAC system designers will increasingly select chilled beams as an alternative to traditional HVAC systems in delivering greater energy savings and higher levels of occupant comfort in a way that is both sustainable and cost-effective.
Endnotes
- Mumma, S.A. (2002). Chilled ceilings in parallel with dedicated outdoor air systems: Addressing the concerns of condensation, capacity and cost. ASHRAE Transactions 2002 (2), 220-231
- Weiger, D. (2009). Master's Thesis entitled The John Hopkins Hospital New Clinical Building, Penn State University, University Park, PA, Department of Architectural Engineering
- ibid.
References and Resources:
Standards:
- AHRI 1240 (Pending Release)
- ASHRAE Standard 200 (Pending Release)
Industry Resources and Design Guides:
- ASHRAE/Rehva Design Guide
- ASHRAE Handbook – HVAC Systems and Equipment, section 20.9
- REHVA Guidebook – Chilled Beam Application Guidebook
Price Industries:
- Engineer's HVAC Handbook, chapter 19
- Online catalog, section L:
- http://www.priceindustries.com/products/section/l-active-passive-beams
- http://www.priceindustries.com/products/category/beams
- Beam selection software :
- Case Study Videos:
- Product Videos:
- Webinars:
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Price Industries is the leading manufacturer of air distribution products in the North American market, and works to bring about the vision of the design community by collaborating on high-quality, high-performing, and customizable air distribution solutions. www.priceindustries.com |
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