2021 ASHRAE Handbook - Foundamentals (SI)

RIYADH KING SALMAN AB, SAUDI ARABIA (WMO: 404380)

Lat:24.722N Long:46.725E Elev:635 StdP: 93.92 Time zone:3.00 (E03) Period:94-14 WBAN:99999
Annual Heating, Humidification, and Ventilation Design Conditions
Humidification DP/MCDB and HR Coldest month WS/MCDB
Heating DB MCWS/PCWD to 99.6% DB
Coldest Month 99.6% 99% 0.4% 1% WSF
99.6% 99% DP HR MCDB DP HR MCDB WS MCDB WS MCDB MCWS PCWD

1 6.2 8.0 -12.6 1.4 17.4 -10.1 1.7 20.8 9.5 16.9 8.8 17.5 2.0 320 0.477

Annual Cooling, Dehumidification, and Enthalpy Design Conditions

Cooling DB/MCWB Evaporation WB/MCDB
Hottest Month MCWS/PCWD to 0.4% DB
Hottest Month 0.4% 1% 2% 0.4% 1% 2%
DB Range
DB MCWB DB MCWB DB MCWB WB MCDB WB MCDB WB MCDB MCWS PCWD

8 13.1 44.9 19.5 44.0 19.1 43.1 18.7 21.4 37.7 20.6 37.9 19.9 38.1 4.4 30

Dehumidification DP/MCDB and HR Enthalpy/MCDB

0.4% 1% 2% 0.4% 1% 2% Extreme Max WB
DP HR MCDB DP HR MCDB DP HR MCDB Enth MCDB Enth MCDB Enth MCDB

18.0 13.9 23.0 16.8 12.9 22.1 15.2 11.6 22.2 65.2 38.3 62.2 37.3 59.8 38.0 27.0

Extreme Annual Design Conditions

Extreme Annual Temperature n-Year Return Period Values of Extreme Temperature
Extreme Annual WS
Mean Standard deviation n=5 years n=10 years n=20 years n=50 years
1% 2.5% 5% Min Max Min Max Min Max Min Max Min Max Min Max

9.2 8.2 7.2 DB 3.4 46.3 2.1 0.9 1.9 46.9 0.7 47.4 -0.5 47.9 -2.0 48.5
WB -0.4 23.7 1.8 1.5 -1.7 24.8 -2.8 25.7 -3.8 26.5 -5.2 27.6

Monthly Climatic Design Conditions

Annual Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
DBAvg 27.0 15.0 17.9 21.7 27.3 33.0 35.7 36.7 36.8 33.5 28.4 21.5 16.5
DBStd 8.33 3.17 3.60 3.53 3.41 2.51 1.54 1.54 1.51 1.91 2.27 3.23 3.34
HDD10.0 4 3 1 0 0 0 0 0 0 0 0 0 1
Temperatures, Degree-Days and HDD18.3 254 112 48 9 1 0 0 0 0 0 0 10 74
Degree-Hours CDD10.0 6222 157 221 362 520 712 772 827 829 704 569 344 203
CDD18.3 3429 8 34 113 271 454 522 568 571 454 311 104 19
CDH23.3 55228 72 316 1133 3478 7454 9289 10271 10318 7628 4203 921 145
CDH26.7 38071 9 84 462 1900 5093 6892 7791 7838 5292 2374 317 18

Wind WSAvg 3.2 3.1 3.6 3.6 3.8 3.5 3.6 3.5 3.2 2.7 2.4 2.8 2.9

PrecAvg 124 14 7 31 37 8 0 0 0 0 1 7 9
PrecMax 318 111 38 123 132 69 0 11 6 0 27 93 70
Precipitation
PrecMin 15 0 0 0 0 0 0 0 0 0 0 0 0
PrecStd 89 22 10 36 40 14 0 2 1 0 5 17 17

DB 27.9 31.8 35.6 40.1 43.8 45.2 46.1 45.8 43.3 39.0 33.6 28.8
0.4%
MCWB 14.3 16.2 16.0 17.7 18.4 19.0 19.9 20.2 19.0 17.3 16.7 15.4
DB 25.2 29.2 33.2 38.1 42.2 44.1 45.0 44.6 42.2 37.4 31.9 26.9
2%
Monthly Design Dry Bulb and Mean MCWB 13.3 14.6 15.6 17.4 18.3 18.7 19.4 19.7 18.7 16.7 15.7 14.7
Coincident Wet Bulb Temperatures DB 23.2 27.1 31.2 36.8 41.0 43.1 44.0 44.0 41.2 36.2 30.2 24.9
5%
MCWB 12.2 13.9 14.9 16.9 18.2 18.4 18.9 19.4 18.3 16.4 15.3 13.7
DB 21.2 25.0 29.2 34.8 39.9 42.1 43.0 43.1 40.1 35.1 28.5 23.0
10%
MCWB 11.8 12.8 14.1 16.6 18.0 18.0 18.6 19.1 17.8 16.3 14.9 13.2

WB 17.3 17.7 19.7 21.0 21.6 20.6 22.3 23.5 21.1 20.2 19.9 18.6
0.4%
MCDB 21.6 24.5 26.3 28.5 32.4 41.8 39.5 37.2 35.6 27.6 25.1 23.3
WB 15.7 16.5 17.8 19.8 20.3 19.6 20.8 21.6 19.8 18.8 18.5 17.1
2%
Monthly Design Wet Bulb and Mean MCDB 20.5 24.1 26.3 29.3 35.0 42.0 41.6 40.4 39.1 30.3 23.9 21.2
Coincident Dry Bulb Temperatures WB 14.5 15.3 16.7 18.9 19.5 19.0 19.8 20.7 19.1 17.9 17.5 15.9
5%
MCDB 20.1 23.9 25.6 29.4 35.9 41.7 42.0 40.6 39.1 32.1 24.1 21.7
WB 13.2 14.1 15.7 18.0 18.8 18.4 19.1 19.9 18.5 17.2 16.5 14.5
10%
MCDB 19.0 23.2 25.1 30.0 36.2 41.1 41.9 41.0 38.5 32.5 24.6 20.8

Mean Daily Temperature Range MDBR 10.5 11.4 11.9 12.1 12.5 13.1 12.9 13.1 13.2 13.0 11.1 10.7
MCDBR 13.4 13.7 14.6 14.1 13.6 13.9 13.4 13.3 13.7 13.9 13.3 13.3
5% DB
MCWBR 6.4 6.0 6.1 5.1 4.6 4.7 4.6 4.6 4.8 5.2 5.5 6.1
 MCDBR 10.3 11.7 11.5 11.9 11.9 13.0 12.5 12.3 12.7 11.9 9.8 9.6
5% WB
MCWBR 6.0 5.8 5.9 4.8 4.2 4.6 4.7 4.6 4.8 5.2 5.5 6.1

taub 0.427 0.471 0.541 0.622 0.644 0.603 0.583 0.574 0.517 0.450 0.461 0.423
taud 1.980 1.854 1.697 1.572 1.531 1.586 1.655 1.675 1.771 1.923 1.904 1.990
Clear Sky Solar Irradiance
Ebn at noon 809 802 767 717 700 724 738 744 776 810 765 792
Edn at noon 160 195 240 277 288 271 253 247 219 179 171 153

RadAvg 4.31 5.16 5.93 6.45 7.19 7.83 7.48 7.12 6.55 5.71 4.42 4.08
All-Sky Solar Radiation
RadStd 0.30 0.29 0.33 0.32 0.28 0.24 0.17 0.16 0.15 0.21 0.31 0.27

Historical Trends

Heating Cooling Degree-Days

DBAvg
99% DB 99% DP 1% DB 1% WB 1% DP HDD10.0 HDD18.3 CDD10.0 CDD18.3
Station Only N/A N/A N/A N/A +0.87 N/A N/A N/A +250 +260
Regional (0 neighbors) +0.33 N/A N/A N/A N/A N/A N/A N/A +112 +103

CDDn Cooling degree-days base n°C, °C-day Lat Latitude, ° Period Years used to calculate the design conditions
CDHn Cooling degree-hours base n°C, °C-hour Long Longitude, ° Sd Standard deviation of daily average temperature, °C
DB Dry bulb temperature, °C MCDB Mean coincident dry bulb temperature, °C StdP Standard pressure at station elevation, kPa
DP Dew point temperature, °C MCDBR Mean coincident dry bulb temp. range, °C taub Clear sky optical depth for beam irradiance
Ebn,noon MCDP Mean coincident dew point temperature, °C taud Clear sky optical depth for diffuse irradiance
Clear sky beam normal and diffuse horizontal irradiances at solar noon, W/m2
Edh,noon MCWB Mean coincident wet bulb temperature, °C Tavg Average temperature, °C
Elev Elevation, m MCWBR Mean coincident wet bulb temp. range, °C Time Zone Hours ahead or behind UTC
Enth Enthalpy, kJ/kg MCWS Mean coincident wind speed, m/s WB Wet bulb temperature, °C
HDDn Heating degree-days base n°C, °C-day MDBR Mean dry bulb temp. range, °C Hours 8/4 & 12.8/20.6 Number of hours between 8 a.m. and 4 p.m with DB between 12.8 and 20.6 °C
PCWD Prevailing coincident wind direction, °,0 = North, 90 = East WS Wind speed, m/s HR Humidity ratio, g of moisture per kg of dry air