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Basis o Design - atkinsglobal.com

ASHRAE JOURNAL OCTOBER 201376 Understanding the Basis of DesignASHRAE defines the BOD as a document that records the major thought processes and assumptions behind Design decisions made to meet the owner s project requirements (OPR). The Design team uses the BOD document to show how their assumptions and specifi-cations will enable the completed project to satisfy the requirements listed in the OPR document. The previous article in this series (ASHRAE Journal, August 2013) noted that the owner can use a well-crafted OPR document as a checklist or scorecard to verify project success. The BOD document needs to be created early on: after the schematic Design is completed, but before creat-ing the actual Design development documents. That s because the BOD must explain the decision processes behind the Design , essentially translating the owner s vision into practical Design criteria and improving the communication process between all parties during the Design phase.

Air-handling units shall include two stages of filtration: The pre-filter shall have a maximum efficiency reporting value (MERV) of 8 (per ASHRAE Standard 52.2-2007),

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Transcription of Basis o Design - atkinsglobal.com

1 ASHRAE JOURNAL OCTOBER 201376 Understanding the Basis of DesignASHRAE defines the BOD as a document that records the major thought processes and assumptions behind Design decisions made to meet the owner s project requirements (OPR). The Design team uses the BOD document to show how their assumptions and specifi-cations will enable the completed project to satisfy the requirements listed in the OPR document. The previous article in this series (ASHRAE Journal, August 2013) noted that the owner can use a well-crafted OPR document as a checklist or scorecard to verify project success. The BOD document needs to be created early on: after the schematic Design is completed, but before creat-ing the actual Design development documents. That s because the BOD must explain the decision processes behind the Design , essentially translating the owner s vision into practical Design criteria and improving the communication process between all parties during the Design phase.

2 As noted in the previous article, the USGBC has made the OPR and BOD documents manda-tory for all LEED-NC certified projects (LEED 2009).Unfortunately, the BOD document is too often forgot-ten until after the Design process. Then something is thrown together which ends up of no use to anyone. Without a BOD document, the CxA cannot fully under-stand and act upon the Design team s actual Practical ConsiderationsTo help ensure easy understandability by the most read-ers, write your BOD document in layman s terms (when-ever possible). Use lots of charts, tables, detailed lists, and graphs. If photos best explain what you want to convey, include them, along with clear and detailed member of the Design team should be a part of preparing the BOD document and then maintaining it throughout the Design process. It s not a job for a junior-level designer or intern.

3 You ll also need to involve the architectural team, as well as the mechanical, plumb-ing, and electrical engineers. And don t forget specialty TECHNICAL FEATUREABOUT THE AUTHORS Vince Briones, , is senior program manager at Atkins in Austin, Texas, and Dave McFarlane is a principal project director at Atkins in Fort Myers, Fla.*This is the third in a series of articles that explain the technical commissioning process for new buildings. The series (and the first article) is titled Technical Commissioning: The Commissioning Process that Works. Some of these articles content is based on ASHRAE Guideline 0-2005, The Commissioning Process (published 2005) and the National Environmental Balancing Bureau (NEBB) Whole Building Systems Technical Commissioning Procedural Standards Manual (revised April 2013). In addition, some of the information in this article has been taken from an unpublished NEBB standard titled NEBB Standard Owner s Project Requirements (OPR) Guideline (June 20, 2011).

4 This article also draws upon an unpublished sample OPR document created by NEBB for the fictional ABC Headquarters Office Building (Jan. 2, 2011).The Basis of Design (BOD) document provides building designers and engi-neers with an effective tool they can use to clearly present to the owner, commissioning agent (CxA), contractors, suppliers, and any other third parties the decision, assumptions, and specifications that are being used to develop the construction documents for a BOD transforms the raw data from the owner s project requirements (OPR) document (the what ) into a detailed, technical, actionable plan (the how ) that will meet the owner s objectives which will also help avoid the scope creep that can derail the project schedule and lead to budget of DesignBY VINCE BRIONES, , MEMBER ASHRAE; AND DAVE MCFARLANE, MEMBER ASHRAET echnical vs.

5 Process Commissioning ASHRAE Used with permission from ASHRAE Journal, October 2013 at This article may not be copied nor distributed in either paper or digital form without ASHRAE s permission. For more information about ASHRAE, visit 2013 ASHRAE JOURNAL77museum s user groups protested that future exhibits could require a dry-pipe fire protection system. The group also cited the museum s own Design -standards documents, which mandated dry-pipe fire protection. The use group further maintained that the fire protec-tion engineer should have known about the dry-pipe mandate, and should have included such a system as standard practice. But no one could recall why a wet-pipe system had been news: Because the project had a thorough BOD document that clearly identified the wet-pipe system change during the Design , the fire protection engineer was able to clearly show the owner how the wet-pipe decision was made.

6 The owner then authorized the return to a dry-pipe system, and agreed that the Design team should not be expected to eat the change. As a result, the designers were able to charge a fair price for the required redesign services. Different Needs, Different DocumentsSometimes architects and engineers confuse the BOD document with the narratives they create during project pursuit. Design professionals sometimes say, We don t need to produce an additional document. We ve already provided the owner with an RFP-based narrative that describes our Design plan. It s essential to understand that the RFP, the early Design narratives, the OPR, and the BOD are all differ-ent documents that serve different purposes. Without this understanding, the Design team can be well into the Design process before the owner realizes the project has taken a turn that deviates from his or her requirements.

7 TECHNICAL FEATURETABLE 1 Sample HVAC Design Design CRITERIAB uilding Ventilation Minimum ventilation rates shall be 5 cfm per person and cfm/ft2 of building surface; the ventilation rate for the entire building shall be 3,000 cfm. Building ventilation rate shall meet the minimum requirements of the latest version of ASHRAE Standard Inside pressure. Ventilation and air conditioning systems shall maintain a positive pressure of in. inside the building (compared to the exterior) to minimize air and dirt infiltration. The volume of fresh air shall be sufficient to maintain positive pressure inside the facility (compared to outside). Infiltration/exfiltration offset. An additional amount of conditioned air shall be included to offset the effects of infiltration and exfiltration. The allowable leakage rate at 50 Pa shall be cfm/ft2 of building surface; maximum infiltration wind speed shall be 15 mph.

8 Air filtration. Air-handling units shall include two stages of filtration: The pre-filter shall have a maximum efficiency reporting value (MERV) of 8 (per ASHRAE Standard ), and the final filter shall have a value of MERV 13. Units shall be sized and selected with respect to the dirty filter condition. Filters shall be of medium efficiency (30%), as defined by the latest version of ASHRAE Standard There shall also be adequate space for filter removal and replacement. Outside air intakes shall be a minimum of 10 ft above the ground and a minimum of 15 ft away from any exhaust-air discharge openings or plumbing vents. Intakes shall be sized so free-air velocities fall below 500 fpm. Intakes shall be equipped bird screens, and with weatherproof and sand-removing Noise Limitations Noise levels. HVAC-generated noise shall not exceed NC 45 in the data center, NC 35 in circulation areas, and NC 30 in open offices, private offices, and conference rooms.

9 Duct velocities for systems of 2 in. of pressure and lower shall not exceed 1,200 fpm; velocities for systems greater than 2 in. shall not exceed 2,400 fpm. Fluid flow and pipe velocities shall be less than 6 fps for pipes less than 4 in. in diameter; for pipes larger than 4 in., velocities shall be less than 8 Servicing and Access Minimal service interruption. The Design shall enable the building s main HVAC equipment to be serviced, maintained, and repaired with minimal interruption to building functions. Shutoff valves shall be provided at each coil. Equipment mounting. All floor-mounted equipment shall rest on a (minimum) concrete housekeeping pad. The Design shall employ vibration-isolating elastomeric pads to reduce transmitted vibration. Accessibility. There shall be 3 ft of access space around each piece of mechanical equip-ment, as well as enough space to allow coils to be to be removed and Detection and Fire Prevention Control standards.

10 Smoke detection and emergency automatic controls shall conform to the latest National Electrical Code (NEC) NFPA 90A and NFPA 72 or consultants such as fire protection, security, and audio/visual should factor BOD mainte-nance into your project schedule. Then update the document at regu-lar milestones, such as the 30%, 60%, 90%, and 100% stages of submitting construction Case in PointMisunderstanding a project s Design intent is one of today s most common construction-related challenges. And one of the greatest benefits of the BOD document is that its clear presenta-tion of the owner s Design intent helps protect the owner, the Design team, the engineers, and the contractors from confusion, misunderstandings, and lost once worked on a museum project for which the primary exhib-its were to be marble sculptures.


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