Data From More Than 8,000 Weather Stations Formulate Updated Climate Design Guidance

From eSociety, June 2017

By Mary Kate McGowan, Associate Editor, News

Designers rely on data from more than 8,000 weather stations throughout the world to design properly sized HVAC systems for different climates.

The “Climatic Design Information” chapter of the 2017 ASHRAE Handbook—Fundamentals is  updated every four years with recent, reliable climate data to help building professionals size and design building components. The Handbook chapter also contributes to ANSI/ASHRAE Standard 169, Climatic Data for Building Design Standards.

The 2017 Handbook chapter includes data from 8,118 stations throughout the world, 1,675 more stations than the 6,443 stations used in the 2013 Handbook. By comparison, there were only 1,464 stations in the 2001 edition—the 2017 update represents a difference of 6,654 stations, or a 454% increase, compared to the 2001 edition.

This increase in the number of stations has also been accompanied by an improvement in the quality of the data.

The reason for the increased number of stations is the availability of the underlying data, according to Didier Thevenard, Ph.D., P. Eng., Member ASHRAE. Thevenard was the lead researcher for the final research papers on updating climatic design data for the 2009 and 2013 versions of Handbook—Fundamentals and the lead reviser for the “Climatic Design Information” chapter in 2017 ASHRAE Handbook—Fundamentals.

The number of stations that have enough data to calculate climate design conditions has increased because the stations’ electronic data collection has improved over the past two decades.

Typically, climatic design conditions are calculated with data from the last 25 years. But stations with as little as eight years of data can also be included in the Handbook. Eight years of data should yield design conditions that are within an acceptable tolerance of those calculated using a 30-year period, according to a preprint of a paper on the climate design data update written by Michael Roth, Ph.D., P. Eng., Member ASHRAE. (Roth, M. 2017. “Updating the ASHRAE climate design data for 2017.” ASHRAE Transactions 123(2). Forthcoming.)

Roth is scheduled to present the update during ASHRAE’s annual conference in Long Beach, Calif.

The data is also available in the updated Weather Data Viewer, which will be published by ASHRAE shortly after the 2017 ASHRAE Handbook—Fundamentals. The viewer includes all 8,118 stations’ data such as degree days to any base, design day temperature, clear sky solar radiation, load calculation data, and a bin data generator.

SITE SELECTION AND DATA COLLECTION

For the most part, each country’s national weather service organization owns the weather stations that are installed in different areas for various reasons, according to Thevenard.

Many of the stations are set up for aviation transportation purposes and are located near airports, which tend to be located in the periphery of cities and not in downtown areas more representative of the built environment, he said. If a city has more than one weather station with enough data, all the stations’ data end up in the Handbook, according to Thevenard.

“This gives users the choice of using the station most representative of the site they are considering: one may be the airport, one downtown, the other in a suburb,” he said.

Others stations might be located at universities to support research efforts, while other stations are installed at ports for marine purposes, he said.

Still other stations are used for agricultural purposes or are installed for specific areas like a station located near a ski station.

A large portion of the data used in the 2017 report comes from the National Oceanic and Atmospheric Administration’s (NOAA) Integrated Surface Database (ISD), a global database that collects data from stations. Most stations have agreements to share their data with NOAA, while other do not transmit data to NOAA, he said. 

Other data points are supplied by other networks such as the Global Historical Climatology Network and FAOClim-Net. Environment Canada mainly provides the Canadian stations’ data, according to Thevenard.

LOCATION, LOCATION, LOCATION

ASHRAE researchers used whatever data was available to produce the 2017 revision. The researchers had no say in deciding where the stations were located, Thevenard said.

“It should also be noted that the locations are dictated by the weather stations themselves, which are not necessarily located exactly where we would prefer them to be,” Thevenard said.

Of the available weather station locations that yielded enough data to be used in the 2017 revision, 2,796, or 34%, were located in North America; 2,265, or 28%, were stationed in Europe; and 1,749, or 22%, were based in Asia.

Almost 70% of the North American weather stations used in the 2017 report were located in the United States.

Some populated, developed countries have more than 100 stations, but other countries are “sparsely represented,” according to Roth’s paper.

“There is a clear correlation between level of economic development and number of weather stations,” Thevenard said. “This is just a guess, but when one has very few resources and the main concern is how people are going to eat, the measurement of wind speed is of secondary importance.”

The U.S. Census Bureau reports that more than 1.2 billion people live in Africa and more than 418 million people live in South America. A total of 290 participating weather stations were located in Africa, and 179 were stationed in South America.

The U.S. Census Bureau reports that more than 190 million people live in Nigeria, but no stations were successfully processed in that country, according to Roth’s paper.

Proportionately, about 16% of the world’s population calls Africa home, but only about 3.6% of the total weather stations were based in Africa. Comparatively, North America, which, with its population of more than 362 million people accounts for about 4.9% of the world’s population, had 34.4% of the total weather stations.

Even if a country does not have a weather station, it can still reap the benefits from the study, according to Thevenard. The effort to make buildings more energy efficient and have a lower environmental impact will help curb global warming for all countries, not just industrial ones, he said. 

2021 REVISION

The next climatic data update is scheduled to be published in the 2021 version of ASHRAE Handbook—Fundamentals, and that revision could include more stations, according to Thevenard.

TC 4.2, Climatic Information, which is responsible for the update, is focusing on a research project (1745-RP) that will allow researchers to calculate climatic design conditions for virtually any location, he said. The project is testing the feasibility of deriving design conditions from gridded-data sets covering the entire world such as such as the Climate Forecast System Reanalysis (CFSR) or the Modern-Era Retrospective Analysis for Research and Applications (MERRA), Thevenard said.

“The research project will determine whether this can be done with sufficient accuracy,” he said.

In the meantime, both Roth and Thevenard are asking for feedback for their work. They both urged those interested to either drop by one of TC 4.2’s meetings scheduled throughout the upcoming annual conference or Roth’s presentation scheduled for 9:45 a.m. June 27 during a Research in HVAC Fundamentals technical paper session.