Engineered Systems - October 2008 - (Page 56)

Cold Climate HVAC Challenges sively achieved non-mechanically through barometric relief points in the building. Passive building pressure control most commonly consists of a gravity-operated damper in the occupied space. When the economizer operates, the positive pressure that develops inside the space pushes air out of the damper and prevents over-pressurization. Building pressure control is important for two reasons: • It is fundamental to attaining the design targets for infiltration and exfiltration. • It enables proper door operation by preventing excessively positive or negative pressure. Both factors affect the performance and longevity of the building and its systems. Direct control of building pressure, whether with a return fan, relief fan, or barometric relief best manages the combined effects of weather, wind, and mechanical ventilation. BUILDING SYSTEM SELECTION The selection of the right HVAC system for buildings in cold climates is subjective and always a topic of discussion amongst design engineers. The old adage about putting five engineers in a room with one problem and getting 25 solutions is certainly more relevant in today’s design environment, simply due to the choices and options available with more advanced technologies. Whether the systems are constant volume, variable volume, all air, a combination of air and hydronics, or any combination of the above, the common denominator in system selection and design always falls back to proper sizing and protection of all the system’s components from exposure to the elements. Simple due diligence and a high level of awareness to the climate in which the systems are being designed is paramount to success. Designing HVAC systems for cold climates presents multiple unique challenges, not unlike mirrored challenges presented when designing systems for hot, humid climates. This information provides a snapshot of a few of the design opportunities and hurdles that must be considered when performing HVAC design work in cold climates. There are specific steps that must be followed and precautions taken to ensure a project that ultimately meets the needs of the client. ES U.S. PATENT 6971871 Miles is an associate and senior mechanical designer with Harriman (Portland, ME). He has over 30 years of experience in educational, health care, and institutional projects. He is a member of ASHRAE and the Association of Energy Engineers (AEE). mprove productivity and employee comfort with energy-efﬁcient Solaronics TRUE DUAL 2-STAGE modulating heaters that save up to 75% in energy costs while providing dry, quiet uniform heat with no drafts or air movement to disturb work. Patented 2-STAGE design provides precise air/gas ﬂow matching at both high and low ﬁre stages for optimum combustion. Furgeson is a senior mechanical engineer with Harriman (Portland, ME). He has nearly 20 years of experience in health care, institutional, and educational projects. He is a licensed professional engineer in Maine and seven other states, and is a member of ASHRAE, the American Society for Healthcare Engineering (ASHE), and AEE. Input 175 at www.esmagazine.com/instantproductinfo 56 En gi neer ed S y stem s October 2008 9/15/08 10:56:08 AM ESM10084Solaronics.indd 1 http://solaronicsusa.com http://solaronicsusa.com http://www.esmagazine.com/instantproductinfo

Table of Contents Feed for the Digital Edition of Engineered Systems - October 2008

Engineered Systems - October 2008 Contents Editor’s Note Letters Back2Basics HVAC Challenge Case in Point Commissioning Building Automation HydroTech HVACR Designer Tips Special Insert: Engineer's Technical Library Fall 2008 Living Wild! Chilled Beams in Chicago Phoenix Convention Center: On The Rise Cold-Climate HVAC Challenges Humidification Strategies For Data Centers & Network Rooms Special Advertising Supplement: Tabb Talk Computers & Software Issues & Events Products Literature & Catalogs Glossary Classifieds Advertiser Index Tomorrow’s Environment

Engineered Systems - October 2008

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