1、444 ASHRAE TransactionsThis paper is based on findings resulting from ASHRAE Research Project RP-1453.ABSTRACT This paper summarizes the preparation of climatic design conditions for the 2009 ASHRAE Handbook Fundamentals. The project (a) redefined new percentiles of monthly dry bulb and wet bulb tem
2、peratures to represent less extreme condi-tions than those used in the past, (b) added new monthly dry bulb and wet bulb coincident temperature ranges which can be used for the derivation of daily temperature profiles, (c) calcu-lated heating and cooling degree-days base 50F (10C) and 65F (18.3C), i
3、n support of various standards including ASHRAE Std. 90.1-2004, and added parameters to accurately evaluate degree-days to any other base, and (d) developed a new clear sky solar irradiance model, to overcome the known limitations of the existing ASHRAE clear sky model and extend its applicability t
4、o the whole world.The most recent 25 years of climatic data (1982-2006 at the time of processing) were used to calculate the revised tables of climatic design conditions. This provides a balance between accounting for long-term trends and the sampling variation owing to year-to-year variation. Proce
5、ssing led to the calcu-lation of climatic design conditions for a total of 5,564 loca-tions worldwide.INTRODUCTIONASHRAE provides tables of climatic conditions for many locations in the United States, Canada and around the world in the Climatic Design Information chapter of its Handbook Fundamentals
6、 (HOF; ASHRAE, 2005a, 2009a). These tables include values such as dry-bulb temperature, wet-bulb temper-ature, dew-point temperature, enthalpy, and wind speed at various frequencies of occurrence over a long-term period, corresponding mean coincident values of some other param-eters, and averages of
7、 some extremes. ASHRAE also sells a companion product, the Weather Data Viewer (ASHRAE, 2005b, 2009b), which can be used to display actual design values, coincident/joint frequency tables, or summary statis-tics for dry-bulb, dew-point, and wet-bulb temperature, as well as enthalpy and wind speed, f
8、or all the locations given in the Climatic Information chapter. Finally the climatic conditions, along with some other data, are the primary component of ASHRAE Standard 169, Weather Data for ASHRAE Building Design Standards (ASHRAE, 2006).ASHRAE Research Project 1453-RP, Updating the ASHRAE Climati
9、c Data for Design and Standards, aimed at updating the climatic design condition tables for inclusion in the 2009 HOF and Standard 169. This update was necessary for the following reasons:The Climatic Information chapter in the 2009 HOF will regroup additional climate information, such as clear sky
10、solar irradiance, which is currently scattered throughout various chapters of the Handbook. This information had to be calculated and added to the cli-matic tables;Project 1363-RP, Generation of Hourly Design Day Weather Data, resulted in the calculation of new climatic design conditions which neede
11、d to be added to the HOF climatic tables;Updating the ASHRAE Climatic Data forDesign and StandardsDidier Thevenard, PhD, PEng Christian A. Gueymard, PhDMember ASHRAEDidier Thevenard is principal of Numerical Logics, Inc., Waterloo, ON, Canada. Christian A. Gueymard is president of Solar Consulting S
12、ervices, Colebrook, NH.AB-10-011 (RP-1453)2010, American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (www.ashrae.org). Published in ASHRAE Transactions (2010, Vol. 116, Part 2). For personal use only. Additional reproduction, distribution, or transmission in either print o
13、r digital form is not permitted without ASHRAEs prior written permission.2010 ASHRAE 445The data from which the climatic tables have been derived is constantly being updated, with more recent years added to the period of record. This enables the cal-culation of design conditions from a longer period
14、 of record, thus enhancing the quality and reliability of the data; the expansion of the tables to a greater number of stations, thus enhancing geographical coverage; and the capture of trends such as the variation of design condi-tions with climate change.This project enabled the recalculation of c
15、limate statis-tics currently in Standard 169 (such as heating and cool-ing degree days), using the same period of record as for the climatic design conditions in the HOF, thus provid-ing consistency between the various calculations.A similar project (1273-RP) completed for the previous edition of th
16、e HOF was summarized in a paper by Thevenard and Humphries (2005), which contains technical details about the algorithms used to calculate the climatic design condi-tions. The 2009 update reused much of the same techniques, and their description is not repeated here. Instead, this paper focuses on t
17、he main differences between the 2005 and 2009 tables, which are covered in the following sections:The selection of new percentiles of monthly dry bulb and wet bulb temperatures to represent less extreme conditions than those in the 2005 Handbook;The addition of new elements resulting from research p
18、roject 1363-RP: dry bulb and wet bulb temperature ranges coincident with the 5% monthly dry bulb or wet bulb design temperatures, which can be used to derive daily temperature profiles;The calculation of heating and cooling degree-days base 50F (10C) and 65F (18.3C), in support of various standards
19、including ASHRAE Std. 90.1-2004, and the development and testing of a new method to evaluate degree-days to any other base;The development of a new clear sky solar irradiance model to overcome the known limitations of the existing ASHRAE clear sky model, and to extend its applicabil-ity to the whole
20、 world. The last section of the paper summarizes the development of the tables themselves and provides statistics about the sites included in the 2009 HOF. NEW PERCENTILES OF MONTHLY DRY BULB AND WET BULB TEMPERATURES The Climatic Design Information chapter of the 2005 HOF lists:the 0.4%, 1% and 2%
21、annual design dry-bulb tempera-tures, which are exceeded 35.1, 87.7 and 175.3 hours in an average year;the 0.4%, 1% and 2% monthly design dry-bulb tempera-tures, which are exceeded 2.9, 7.3 and 14.6 hours in an average month.As the revision of the chapter was underway, the question was raised as to
22、whether these monthly design temperatures were too extreme and would lead to significant oversizing of equipment.There is no easy way to answer that question, but one simple guideline could be that monthly design temperatures for the hottest month should be roughly equivalent to the yearly design te
23、mperatures. A comparison of dry-bulb temperatures corresponding to various frequencies of occur-rence in the hottest month, calculated for all 4,422 locations contained in the 2005 HOF, to the average yearly design condi-tions, lead to establishing a rough correspondence between yearly and monthly d
24、esign conditions, summarized in Table 1. A simple rule of thumb is that the monthly percentile to use is five times the yearly percentile. This is illustrated in Figure 1 which compares the 5% monthly design dry bulb temperature for the hottest month to the 1% yearly design dry bulb temper-ature for
25、 all stations in the 2005 HOF. The information is presented both as a scatter plot and as a histogram (similar graphs can be plotted for other frequencies of occurrence). The correlation between monthly and yearly values is of course not perfect: it depends on how temperatures are distributed throug
26、hout the year. Nevertheless, it is apparent that over 90% of monthly design conditions are within 1C of their yearly counterparts. This was a strong argument to use the 2%, 5% and 10% monthly design conditions in the 2009 HOF, instead of the 0.4%, 1% and 2% monthly design conditions that were used i
27、n the 2005 edition.After some discussion, it was decided to nevertheless retain the 0.4% monthly conditions in addition to the 2%, 5% and 10% values; the rationale is that the 2% monthly value would not be extreme enough for some applications. Although the choice would typically be up to building ow
28、ners and designers, the various monthly percentiles could be suggested depending on the type of design considered:0.4%: critical process, hospital operating rooms, etc.5%: corporate headquarter, upscale hotel, patient room, etc. Table 1. Approximate Correspondence between Yearly Design Dry-Bulb Temp
29、eratures and Monthly Design Dry-bulb Temperatures for the Hottest MonthYearly DesignDry-Bulb TemperatureMonthly Design Dry-Bulb Temperature for the Hottest Month0.4% 2%1% 5%2% 10%2010, American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (www.ashrae.org). Published in ASHR
30、AE Transactions (2010, Vol. 116, Part 2). For personal use only. Additional reproduction, distribution, or transmission in either print or digital form is not permitted without ASHRAEs prior written permission.446 ASHRAE TransactionsFigure 1 Comparison of 5% monthly design dry bulb temperatures for
31、the hottest month to 1% yearly design dry bulb temperatures for all stations in the 2005 HOF. Scatter plot (top) and histogram of differences (bottom).2010, American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (www.ashrae.org). Published in ASHRAE Transactions (2010, Vol.
32、116, Part 2). For personal use only. Additional reproduction, distribution, or transmission in either print or digital form is not permitted without ASHRAEs prior written permission.2010 ASHRAE 44710%: competitive building, retail space, speculative office building.The 2009 HOF therefore lists the m
33、onthly 0.4%, 2%, 5% and 10% design dry and wet bulb temperatures, as well as their coincident wet bulb and dry bulb temperatures. COINCIDENT DRY BULB AND WET BULB TEMPERATURE RANGESBackgroundTwenty-four-hour weather data sequences are required as input for many HVAC design procedures including resid
34、ential and non-residential cooling load calculations (both Heat Balance and Radiant Time Series), fenestration heat gain calculation, and equipment performance analyses. Calcula-tions are often done for multiple conditions (all months of the year, for example). It is impractical to publish multiple
35、24-hour sequences for the thousands of sites listed in the Fundamentals climatic data tables. Instead, sequences are derived from a few tabulated design conditions using models. A 24-hour dry bulb temperature profile is generated by application of a generic profile to the design temperature and the
36、daily range. ASHRAE has long published a single generic dry-bulb profile for cooling, found most recently in Chapter 28, Table 2 of 2005 Fundamen-tals. In that same chapter, TC 4.2 has added a method for gener-ating coincident hourly wet-bulb temperature based on an assumption of constant absolute h
37、umidity. The models for generation of 24 hour sequences in the 2005 Handbook had several shortcomings. In particular: The source and geographic applicability of the generic dry bulb profile are not known (no reference has been located for the method).The profile is generally applied to the average d
38、aily range, as opposed to the daily range coincident with design conditions, apparently due to prior limitations in available data.The profiles represent only the high dry-bulb (“hot day”) condition; some design problems require analysis under conditions of high wet-bulb (enthalpy) or high dew-point
39、 (absolute humidity).Finally, the wet bulb method added in the 2005 Funda-mentals is known to be approximate at best and was included only because some source for the data was required for latent cooling load calculations. New Temperature ProfileIn response to these shortcomings, ASHRAE sponsored Re
40、search Project 1363-RP, Generation of hourly design-day weather data (Gard Analytics, 2009). This project used weather data from 21 cities with a variety of climatic condi-tions to develop a daily profile which describes the variation of dry bulb and wet bulb temperature on design days, identi-fied
41、as days with high dry bulb or high wet bulb temperatures. The profile defines the hourly temperature as a fraction of the difference between the daily high and low, as described by the design temperature and the design daily range. A single profile was found to be applicable to all climates and time
42、s of the year for both dry bulb and wet bulb profiles. Dew point temperature variations were found to be highly variable, such that no single profile can provide reliable predictions. Research project 1453-RP built upon the findings of 1363-RP and reformatted them in such a way that the desired dail
43、y dry bulb and wet bulb temperature ranges could be calcu-lated from historical data at the same time as other design conditions. The daily ranges are coincident with high dry bulb or high wet bulb conditions in the sense that they are aver-aged over days for which the maximum dry bulb or wet bulb t
44、emperatures exceeds the 5% monthly design values. There are therefore 4 design day profiles: dry bulb and wet bulb profiles on the dry bulb design day, and dry bulb and wet bulb profiles on the wet bulb design day. In practical terms, the calculation is performed via a mean daily temperature range,
45、max daily temperature joint frequency matrix, where temperature can be either the dry bulb or the wet bulb temperature. This enables to prepare the calculation of the mean daily temperature range without knowing the design temperature for which it will be calculated; the method is simply a variation
46、 of the one used for other coincident design conditions (see Thevenard and Humphries, 2005). The processing software simply calculates the mean daily temper-ature ranges for all bins of max daily temperature, then proceeds by linear interpolation to calculate the temperature range corresponding to t
47、he actual design temperature.Based on the analysis of 21 cities mentioned above, the 1363-RP profile was found to represent adequately the varia-tion of dry bulb temperature and wet bulb temperature during an average design day. This profile is obtained by subtracting the fraction f of the dry- or w
48、et-bulb daily range from the dry- or wet-bulb design temperature. Fraction f is listed in Table 2; in that table, the time h should be understood as the apparent solar time or, if it is not practical to calculate it, the standard Table 2. Fraction of Daily Temperature RangeTime, h f Time, h F Time,
49、h f1 0.88 9 0.55 17 0.142 0.92 10 0.38 18 0.243 0.95 11 0.23 19 0.394 0.98 12 0.13 20 0.505 1.00 13 0.05 21 0.596 0.98 14 0.00 22 0.687 0.91 15 0.00 23 0.758 0.74 16 0.06 24 0.822010, American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (www.ashrae.org). Published in ASHRAE Transactions (2010, Vol. 116, Part 2). For personal use only. Additional reproduction, distribution, or transmission in either print or digital form is not permitted without ASHRAEs prior written permission.448 ASHRAE Transactionstime of the closest meridian. Not
