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Title: Comparison of Microclimate Simulated weather data to ASHRAE Clear Sky Model and Measured Data

Abstract

In anticipation of emerging global urbanization and its impact on microclimate, a need exists to better understand and quantify microclimate effects on building energy use. Satisfaction of this need will require coordinated research of microclimate impacts on and from “human systems.” The Urban Microclimate and Energy Tool (Urban-MET) project seeks to address this need by quantifying and analyzing the relationships among climatic conditions, urban morphology, land cover, and energy use; and using these relationships to inform energy-efficient urban development and planning. Initial research will focus on analysis of measured and modeled energy efficiency of various building types in selected urban areas and temporal variations in energy use for different urban morphologies under different microclimatic conditions. In this report, we analyze the differences between microclimate weather data sets for the Oak Ridge National Laboratory campus produced by ENVI-met and Weather Research Forecast (WRF) models, the ASHRAE clear sky which defines the maximum amounts of solar radiation that can be expected, and measured data from a weather station on campus. Errors with climate variables and their impact on building energy consumption will be shown for the microclimate simulations to help prioritize future improvement for use in microclimate simulation impacts to energy usemore » of buildings.« less

Authors:
 [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1376465
Report Number(s):
ORNL/TM-2017/241
74622
DOE Contract Number:
AC05-00OR22725
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES

Citation Formats

Bhandari, Mahabir S. Comparison of Microclimate Simulated weather data to ASHRAE Clear Sky Model and Measured Data. United States: N. p., 2017. Web. doi:10.2172/1376465.
Bhandari, Mahabir S. Comparison of Microclimate Simulated weather data to ASHRAE Clear Sky Model and Measured Data. United States. doi:10.2172/1376465.
Bhandari, Mahabir S. Thu . "Comparison of Microclimate Simulated weather data to ASHRAE Clear Sky Model and Measured Data". United States. doi:10.2172/1376465. https://www.osti.gov/servlets/purl/1376465.
@article{osti_1376465,
title = {Comparison of Microclimate Simulated weather data to ASHRAE Clear Sky Model and Measured Data},
author = {Bhandari, Mahabir S.},
abstractNote = {In anticipation of emerging global urbanization and its impact on microclimate, a need exists to better understand and quantify microclimate effects on building energy use. Satisfaction of this need will require coordinated research of microclimate impacts on and from “human systems.” The Urban Microclimate and Energy Tool (Urban-MET) project seeks to address this need by quantifying and analyzing the relationships among climatic conditions, urban morphology, land cover, and energy use; and using these relationships to inform energy-efficient urban development and planning. Initial research will focus on analysis of measured and modeled energy efficiency of various building types in selected urban areas and temporal variations in energy use for different urban morphologies under different microclimatic conditions. In this report, we analyze the differences between microclimate weather data sets for the Oak Ridge National Laboratory campus produced by ENVI-met and Weather Research Forecast (WRF) models, the ASHRAE clear sky which defines the maximum amounts of solar radiation that can be expected, and measured data from a weather station on campus. Errors with climate variables and their impact on building energy consumption will be shown for the microclimate simulations to help prioritize future improvement for use in microclimate simulation impacts to energy use of buildings.},
doi = {10.2172/1376465},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Thu Jun 01 00:00:00 EDT 2017},
month = {Thu Jun 01 00:00:00 EDT 2017}
}

Technical Report:

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  • Horizontal ground visibility is used as a measure of atmospheric turbidity and thus serves as the variable to determine transmittance due to aerosols. On this basis, the ASHRAE algorithm to calculate the solar irradiance is reworked to improve the range of applicability for all conditions of atmospheric turbidity. The use of maps (for clearness numbers) and charts becomes unnecessary.
  • The proposed ASHRAE Standard 152P ''Method of Test for Determining the Design and Seasonal Efficiencies of Residential Thermal Distribution Systems'' (ASHRAE 2002) has recently completed its second public review. As part of the standard development process, this study compares the forced air distribution system ratings provided by the public review draft of Standard 152P to measured field results. 58 field tests were performed on cooling systems in 11 homes in the summers of 1998 and 1999. Seven of these houses had standard attics with insulation on the attic floor and a well-vented attic space. The other four houses had unventedmore » attics where the insulation is placed directly under the roof deck and the attic space is not deliberately vented. Each house was tested under a range of summer weather conditions at each particular site, and in some cases the amount of duct leakage was intentionally varied. The comparison between 152P predicted efficiencies and the measured results includes evaluation of the effects of weather, duct location, thermal conditions, duct leakage, and system capacity. The results showed that the difference between measured delivery effectiveness and that calculated using proposed Standard 152P is about 5 percentage points if weather data, duct leakage and air handler flow are well known. However, the accuracy of the standard is strongly dependent on having good measurements of duct leakage and system airflow. Given that the uncertainty in the measured delivery effectiveness is typically also about 5 percentage points, the Standard 152P results are acceptably close to the measured data.« less
  • A detailed comparison was made between five simple broadband models for clear sky global insolation. Compared models were those of Atwater and Ball, Davies and Hay, Watt, Hoyt, and Lacis and Hansen. A sixth simple model, called the Bird model, has been formulated by using parts of these five models and by comparison with the results from three rigorous radiative transfer codes. All of the simple models provide results that agree within < 10% with the three rigorous codes when the sun is in the zenith position. The Bird and Hoyt models agree within 3% with each other and withmore » the results of the rigorous codes. However, the Bird model is easier to implement and has broader application than the Hoyt model.« less
  • Clouds profoundly affect our weather and climate due, in large part, to their interactions with radiation. Unfortunately, our understanding of these interactions is, at best, incomplete, making it difficult to improve the treatment of atmospheric radiation in climate models. The improved treatment of clouds and radiation, and a better understanding of their interaction, in climate models is one of the Department of Energy's Atmospheric Radiation Measurement (ARM) Program's major goals. To learn more about the distribution of water and ice, i.e., clouds, within an atmospheric column, ARM has chosen to use the remote sensing of clouds, water vapor and aerosolsmore » at its three climatologically-diverse sites as its primary observational method. ARM's most heavily instrumented site, which has operated continuously for more than a decade, is its Southern Great Plains (SGP) Central Facility, located near Lamont, OK. Cloud-observing instruments at the Central Facility include the Whole Sky Imager, ceilometers, lidar, millimeter cloud radar, microwave radiometers and radiosondes.« less