scope:

INTRODUCTION

PURPOSE OF THE GUIDE

ASHRAE Design Guide for Natural Ventilation assists owners, architects, engineers, facilities personnel, and building design professionals in exploring the feasibility of natural ventilation for their project during the early phases of design. While many in the industry can see the appeal of natural ventilation for environmental stewardship concerns, some reticence and confusion over the application and interpretation of current related standards exist. This may be because that there is currently not an ASHRAE-endorsed methodology that establishes a rigorous analytical path, and the inputs and equations necessary to complete even a feasibility analysis are located in disparate standards and guidance documents. This guide consolidates and organizes the key information necessary to perform a feasibility analysis by excerpting content when approved by the originating authors or by reference to information in the public domain.

The guide presents a logical sequence of activities to support an evidence-based decision to pursue natural ventilation and/or natural conditioning so that design teams can ask and answer the right questions at the right time during the early design process. So often design teams do not fully appreciate the entire complexity of the code compliance process or the extraordinary reliance on changing outdoor air conditions when first presenting natural ventilation as a form of sustainability measure. This guide provides not only the ordering of content from twenty independent codes, guides, and standards that influence natural ventilation design, it also identifies for the reader several free or low-cost tools for accessing weather data or performing early-stage analysis. Combined with a demonstration of analysis results and their interpretation, the guide offers a step-by-step road map through the critical decisions that a design team should make before embarking on a whole building design reliant on natural ventilation. The progress from conception to fruition for a natural ventilation scheme is one of collaborative review of critical analysis results by a design team.

Natural ventilation relies on a variable source of air movement and cooling capacity. Owners and tenants must be aware not only of the average expected results but also of the frequency of the extreme conditions for the current day and in a future climate-changed condition. Natural ventilation as a comfortconditioning method will always be compared to HVAC schemes that are easier to control from a predictability perspective. Thus, the social acceptability of a natural ventilation scheme is as important to its success as its technical feasibility. This guide intends to present a logical process of minimum steps and analyses necessary to facilitate decision-making by key stakeholders.