Time filter

Source Type

Alameda, CA, United States

Taylor S.T.,Taylor Engineering
ASHRAE Journal | Year: 2016

Underfloor air-distribution (UFAD) systems went from the next best thing among HVAC systems in the late 1990s and early 2000s to few and far between after 2010, at least in the San Francisco Bay Area. The reason is simple: they have not worked very well! At least that is the case when using the most common U.S. designs. While the convenience of the underfloor plenum for wiring was a real benefit, and surveys show that occupants perceive much better indoor air quality compared to overhead systems, the hype about improved comfort and energy savings has not been realized for most projects. Source

Taylor S.T.,Taylor Engineering
ASHRAE Journal | Year: 2014

Steven Taylor discusses how to select and control economizer dampers in VAV systems. For VAV systems using Relief Dampers or Relief Fans pressure drop and supply fan energy can be reduced by sequencing the outdoor air and return air dampers. The pressure drop savings is readily apparent at the 50% outdoor air signal: the two dampers are both wide open rather than both half closed. This substantially reduces pressure drop through the mixing plenum, particularly if the dampers have opposed blade action. One important point in selecting economizer outdoor air and return air dampers is that the concept of damper authority does not apply. The damper authority concept applies to dampers that throttle airflow but economizer dampers do not; they are mixing dampers and are not intended to vary overall airflow. For VAV systems using Relief Dampers the most important damper from a sizing perspective is the relief damper (D-1). The relief system relies on build?ing pressurization to cause excess outdoor air to relieve to atmosphere. For VAV systems using Return Fans with Airflow Tracking control, the outdoor air damper can be either PBD or OBD since it is simply open or closed. When using Direct Pressure control, relief dampers should be OBDs and sized for a pressure drop equal to 7% to 15% of the relief path total pressure drop. Source

Taylor S.T.,Taylor Engineering
ASHRAE Journal | Year: 2015

VAV systems are the most common HVAC system for commercial buildings, but design practices vary widely around the country and even among design firms in a given area. Some of the variation is due to local construction practices and labor costs, but most of the variation, in the author's experience, is due simply to how engineers are taught by their mentors in their early years of practice; design techniques and rules-of-thumb are passed down through the generations like family cooking recipes with little or no hard analysis of whether they are optimum from a life-cycle cost perspective. Copyright 2015 ASHRAE. Source

Taylor S.T.,Taylor Engineering
ASHRAE Journal | Year: 2015

For many years, ASHRAE/IES Standard 90.1 has required that variable air volume (VAV) duct static pressure setpoint be reset based on damper position, and that variable speed pump differential pressure setpoint∗be reset by valve position for systems with direct digital controls (DDC). Copyright 2015 ASHRAE. Source

Feng J.,Taylor Engineering | Schiavon S.,University of California at Berkeley | Bauman F.,University of California at Berkeley
Energy and Buildings | Year: 2016

Impacts of solar shortwave radiation are not taken into account in the standardized design methods in the current radiant system design guidelines. Therefore, the current methods are not applicable for cases where incident solar is significant. The goals of this study are to: (1) use dynamic simulation tools to investigate the impacts of solar radiation on floor cooling capacity, and (2) develop a new simplified method to calculate radiant floor cooling capacity when direct solar radiation is present. We used EnergyPlus to assess the impacts of solar for different design conditions. The simulation results showed that the actual cooling capacities are in average 1.44 times higher than the values calculated with the ISO 11855 method, and 1.2 times higher than the ASHRAE method. A simplified regression model is developed to improve the predictability of ISO methods. The new model calculates the increased capacity as a function of the zone transmitted solar and the characteristic temperature difference between the hydronic loop and room operative temperature. © 2016 Elsevier B.V. All rights reserved. Source

Discover hidden collaborations