ASHRAE Journal- September 2008

full knowledge of the statistical likelihood of discomfort. This information must be held up against the expectations of the occupant populations for the given application. Future Steps and Lessons Learned Atria Louvers Open Hallway Vent Open As can be seen from the comparison table, three of the four case study buildings are just in the process of opening and do not yet have documented energy data or post-occupancy evaluations, although most are targeted to do so in late 2008 and through 2009. The Kirsch Center has had its one-year LEED-related postoccupancy evaluations with positive results from the permanent staff within the building and won the Center for the Built Environment’s Livable Buildings award. What is known from the collection of buildings is that the following are essential to making a BMS-involved mixed mode building work from day one: A client who is committed to the design scheme after the early-phase exploration; An analysis team capable of delivering accurate, peer-reviewed conﬁdencebuilding calculation results that predict the distribution of air and temperature in the naturally ventilated or conditioned spaces; A design team that is committed to resolving all auxiliary issues related to delivering natural ventilation as a viable environmental system (i.e., acoustics, fire, opening positions, building envelope performance, security, outdoor air quality, furniture and partition design, daylighting and lighting controls); An authority-having-jurisdiction willing to entertain the natural ventilation approach; A general contractor who understand how the system and its associated components will work; A controls contractor who has the technical ability to work beyond the usual “canned” subroutines and can provide unique programming sequences to control devices outside of the typical HVAC scope; A fully commissioned controls system that is pretested and trended for temper48 ASHRAE Journal Atria Windows (1st–3rd Floors) Open Green Signal (1st – 3rd Floors) Window Awnings (1st – 3rd Floors) (Actuated) Open Atria Windows (1st–3rd Floors) Open Figure 3: Operating principles for the Yang and Yamazaki Environment and Energy building. ature and device response status in each type of naturally ventilated space; The systematic education of the occupants regarding the intent of the building design and their role in working with the building and the facilities manager; and An acknowledgement by all parties that these buildings are site-speciﬁc with design based on assumptions and simulations, and will take some tweaking during the ﬁrst year to adjust setpoints for the actual internal loads in the asconstructed building envelope. Because of the limited pool of evaluated buildings, lessons learned on naturally ventilated buildings come primarily from reviewing case studies. The burden is on each design engineer to familiarize himself with the available studies and to make a professional judgment regarding applicability of the approach, once he has corrected for climate, occupancy type, and component conﬁguration. If natural ventilation is to be more widely accepted in the U.S. as an alternate approach, systematic research is required similar to the work of Dr. Gail Brager at the Center for the Built Environment at the University of California, Berkeley.4 The owners of the four most recent projects in this article know that the works are educational, somewhat experimental attempts to push constructed mixed mode examples into the AEC industry’s consciousness. Committed throughout the design process to the hope of natural ashrae.org Figure © Arup Planetarium 81.0 80.5 80.0 Temperature (°F) 79.5 79.0 78.5 78.0 77.5 77.0 76.5 Rainforest 76.0 75.5 74.5 74.0 Figure 4: Sample results from the computational ﬂuid dynamics analysis of the California Academy of Sciences Exhibition Hall. ventilation’s realization, they are equally committed to publically disseminating data and lessons learned as they live through their ﬁrst years of operation. References 1. Center for the Built Environment at the University of California, Berkeley Mixed Mode Web Site. www.cbe.berkeley.edu/ mixedmode/aboutmm.html. 2. Chartered Institution of Building Services Engineers. 2005. Natural Ventilation in Non-Domestic Buildings. London: CIBSE. 3. U.S. Green Building Council. 2006. LEED® for New Construction Version 2.2 Reference Guide, Second Edition. 4. Brager, G., de Dear. 2000. “A standard for natural ventilation.” ASHRAE Journal 42(10):21 – 28. September 2008 Figure © Arup http://www.cbe.berkeley.edu/mixedmode/aboutmm.html http://www.cbe.berkeley.edu/mixedmode/aboutmm.html http://ashrae.org

Table of Contents Feed for the Digital Edition of ASHRAE Journal- September 2008

ASHRAE Journal- September 2008 Section: Contents Contents Section: Commentary Options for Sustainability Section: Industry News The Silk Route for Energy Solar Thermal Is Unrealized Opportunity Industry Groups Sue City of Albuquerque Section: Letters Letters Section: Meetings and Shows Meetings and Shows Section: Feature Articles Article-Radiant Floor Cooling Systems Article-HVAC Design for Sustainable Lab Article-Mixed Mode Ventilation Article-Single- Design Considerations For Active Chilled Beams Article-Acoustic Design In Green Buildings Article-Teams, Contracts & BIM Section: Building Sciences Some Old Lessons Distilled Section: Washington Report Energy in Federal Buildings Section: Products HVAC&R Product Showplace Section: Emerging Technologies Toplighting & Lighting Controls For Commercial Buildings Section: Special Products Fans & Blowers Section: Classified Ads Classified Ads Section: Advertising Index Advertising Index

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