Search Results for: air changes per hour

Seminar 57 : The History of the Use of Air Changes per Hour in HVAC Codes, Standards and Guidelines

Seminars

Seminar 52 -- Without Ventilation Effectiveness, Air Change per Hour Is Just a Number

Conference Proceeding

Seminar 52 -- Without Ventilation Effectiveness, Air Change per Hour Is Just a Number

Seminar 52 -- Without Ventilation Effectiveness, Air Change per Hour Is Just a Number

Conference Proceeding

Seminar 52 -- Without Ventilation Effectiveness, Air Change per Hour Is Just a Number

Atria Smoke Exhaust: 3 Approaches to Replacement Air Delivery

Journal

Smoke exhaust requirements for atria, as mandated in recent building codes can include exceptionally high exhaust rates. Previous guidelines for atrium smoke exhaust system volume (often given as 6 air changes per hour) are inadequate3 in many cases as shown by sophisticated computer models and actual fire experience.

Impact of New Ventilation Guidance, Standard 241 on Energy Costs, Carbon Emissions: Why Equivalent Clean Airflow Doesn’t Have to Be Expensive

Journal

This column is a detailed review of simulation results that looked at the energy and carbon impacts of outdoor air ventilation versus hybrid strategies that combine outdoor air ventilation with air cleaning to meet the newly established CDC target (air changes per hour [ach]) and ASHRAE Standard 241, Control of Infectious Aerosols, equivalent clean airflow (ECAi) for commercial, residential and health-care space types.

CFD Analysis for Design Optimization of a Pharmaceutical Cleanroom

Journal

The computational fluid dynamics (CFD) study in this article evaluates the impact of air changes per hour (ach) and the locations of supply diffusers on the airflow patterns and the resulting distribution of particles in the critical zone of a pharmaceutical cleanroom, which is used for manufacturing sterile and nonsterile drugs and medical products and often require a high level of cleanliness to maintain an aseptic environment.

Ventilation Heat Recovery For Laboratories

Journal

Laboratories typically require 100% outside air at high ventilation rates - between 6 and 12 air changes per hour - primarily for safety reasons. The heating and cooling energy needed to condition this air, as well as the fan energy needed to move it, often is five times greater than the amount of energy used in most offices for these same purposes. Energy recovery can substantially reduce the mechanical heating and cooling requirements associated with conditioning ventilation air in most laboratories. As a result of the lower peak heating and cooling requirements with energy recovery, heating and cooling systems can be downsized.

Investigating the applicability of Standard 62.1's Ventilation Rate Procedure for Healthcare Rooms

Report

The research reported here reveals new opportunities in considering how healthcare ventilation systems are designed and operated. The long-standing, volume-based air-change method used in ASHRAE Standard 170 drives large outdoor air requirements in some space types, even though the dominant airborne risk in modern healthcare settings (infectious aerosols) is governed by clean-air delivery and airflow effectiveness, not outdoor air alone. Traditionally, ASHRAE Standard 170 Ventilation of Health Care Facilities has dictated ventilation rates using air change per hour (ACH), a method rooted in mid-20th-century hospital guidelines, and which bases both outdoor air ventilation and overall space airflow on space volume. This project evaluates whether healthcare spaces can move from “air changes per hour” to the same rational, transparent framework used across most other buildings—the ASHRAE Standard 62.1 Ventilation Rate Procedure (VRP), which sets outdoor air as the sum of an area-based rate and a people-based rate tied to occupancy and activity.

ASHRAE Epidemic Task Force Releases Updated Building Readiness Guide

Learn more about ASHRAE Epidemic Task Force Releases Updated Building Readiness Guide at ashrae.org

Interpretations For Standard 170-2008

Learn more about Interpretations For Standard 170-2008 at ashrae.org