Austin Climate Data. csd. Natalie Ward

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1 Austin Climate Data Natalie Ward picture cover page minimum resolution 300 dpi width of the picture not wider than the text blocks height of the picture minimum 0.6 from last text block csd Center for Sustainable Development

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3 UTSoA - Meadows Fellowship Seminar Austin Climate Data Natalie Ward Fig. 01 Austin location within Texas Basic Information Latitude: ( N) Longitude: ( W) Time zone: UTC-6 hours Country: Texas, United States Continent: Americas Sub-region: Northern America Altitude: ~170 m (560 ft) Climate Region Austin is located in central Texas, on the border between a sub-tropical humid climate and a sub-tropical subhumid climate, as seen in Figure 02. Both climates are noted to have warm summers, while the sub-tropical subhumid climate also is noted to have dry winters. Within Texas, the variety of climate types is due to mountain ranges to the west, proximity to the Gulf of Mexico and the southern Great Plains, low latitudes, and shifts of elevation from high plains and mountains to the coastal plains. Due to the proximity to the Gulf of Mexico and terrain, Texas is inflicted with a lot of severe weather including hurricanes and cyclones. The shift of climate regions is apparent not only in the climate types, but also is evident in the correlating patterns reflected in related maps such as the precipitation map of Texas. 1 1

4 UTSoA - Meadows Fellowship Seminar Precipitation Due to Austin s climate region, it reflects a moderate level of precipitation annually. As illustrated in Figure 3, the average annual precipitation values for Austin range from 32 to 36 inches per year. This is much lower to other cities such as New Orleans which get an average of 61.9 inches per year.2 In Figure 4, average monthly precipitation is charted, reflecting that there are two peaks that occur in April and September. These two months not only contain the highest average monthly precipitation levels, but also contain the highest daily record levels with values of 10 and 15 inches respectively. Although the average monthly and daily record charts are not identical curves, there is a strong correlation between months of high precipitation and steeper daily amounts of precipitation, as seen in the two charts of Figure 4. Fig. 02 Regions of climate classification in Texas Temperature As a whole, Texas is known for warm weather. However, many parts of the state have more moderate winters that are dry rather than humid. Since Austin lies on the border between two climate zones, it has portions of the year which are extremely humid and others that are less humid. The average monthly temperatures seen in Figure 4 show a range of only 40 degrees between the lowest and highest months. However, the records high and low temperatures reflect extremes as low as -2 F in January and as high as 112 F in September. In addition to the extreme temperatures, one needs to factor in the humidity, which if high can begin to sway the human Fig. 03 Annual precipitation (inches) in Texas from 1951 to 1980

5 Austin Climate Data Average Monthly Temperatures ( F) and Precipitation (in) January February March April May June July August September October November December Average High Average Low Average Precipitation Average Monthly Temperatures Average Monthly Precipitation Temperature (F) High Low Precipitation (in) Precipitation Record Daily Temperatures and Precipitation January February March April May June July August September October November December Record High Year Record Low Year Record Precipitation Year Record Daily Temperatures Record Daily Precipitation Temperature (F) High Low January February March April May June July August September October November December January February March April May June July August September October November December January February March April May June January February March April May June July August September October November December July August September October November December Precipitation (in) Precipitation Fig. 04 Average temperature and precipitation for Austin, TX. (Data taken at Camp Mabry, see Appendix A) 3

6 UTSoA - Meadows Fellowship Seminar perception of temperatures to higher extremes in the summer and cooler extremes in the winter. Solar Located at 30 N latitude, Austin resides in a part of the country that receives a large amount of sunlight. As seen in Figure 5, on average Austin maintains 15 hours of daytime in the summer and 11 hours of daytime in the winter. Since Austin lacks heavy cloud cover, there is a range of 50-75% of available sunlight throughout the year. This range is extremely important when considering methods such as solar energy, since the solar benefit has a lot of potential. Likewise, the large quantity of sun affects building designs due to possibilities of extreme solar heat gain and glare issues from large amounts of sunlight. All of these issues can be incorporated into building design to allow for optimization of the solar impact in Austin. Fig. 05 Sun rise and sun set times Fig. 06 Austin wind roses annually from 1984 to 1992 Wind Within Austin, there is wind that is dominant on the North and South Axis, with some variety to the East. Overall, Austin mainly contains wind under 21 knots (35.4 f/s), with the majority of the winds ranging from 7 to 10 knots (11.8 f/s f/s). As a comparison, Chicago has an overall average of 9.25 knots (15.6 f/s) annually while Austin averages at 7.7 knots (13 f/s). 3 In addition to the varying average wind speeds, Chicago allows for greater wind speeds than Austin while also creating larger percentages of time at these higher wind speeds. In addition to these factors, it also has a larger variety of wind directions than Fig. 06 Sun path diagram 4

7 Austin Climate Data Percentage of Possible Sunshine Austin, possibly due to the proximity to Lake Michigan and the varied built environment and terrain. Percetantage of Available Hours January February March April May June July August September October November December January February March April May June July August September October November December Fig. 07 Possible sunshine hours Austin Zero Energy Homes In 2006, a bill was passed in Austin to propose Zero Energy Capable Homes Initiative. This type of home is defined as one that is energy-efficient enough to be net zero energy homes with the addition of on-site or its equivalent, energy generation. 5 Within the bill, it devises a slow shift in codes throughout the years leading up to 2015 that will result in all new single-family home designs to be zero energy by This will result in increased energy efficiencies from today s standards and allow for large reductions in energy bills for residents. With an assumption of 6,400 homes being built in Austin in the next year, there would be a carbon reduction from these homes amounting to 178,477 acres of forest or removing 22,814 cars from the road. 4 In Figure 10, the chart defines various factors which are incorporated into the design of the zero energy homes, including temperature values and specific U-values and R-Factors to be used as minimum values for specific elements in the design process. Fig. 08 Austin annual wind roses 5

8 UTSoA - Meadows Fellowship Seminar Variable J F M A M J J A S O N D Insolation, kwh/m 2 /day Clearness, Temperature, F Wind speed, mph Precipitation, in Wet days, d Relative humidity, % Fig. 09 Solar energy and surface meteorology Exterior Design Conditions. The design parameters in Table shall be used for calculations under this code. TABLE CONDITION VALUE Winter a, Design Dry-bulb ( o F) 28 Summer a, Design Dry-bulb ( o F) 99 Summer a, Design Wet-bulb ( o F) 74 Degree days heating b 1735 Degree days cooling b 2862 Climate Zone c 2.2 For SI: deg C=[(deg F)-32]/1.8. CLIMATE - SUB CLIMATE ZONE 2.2 MAXIMUM WINDOW TO WALL AREA RATIO TABLE INSULATION AND FENESTRATION REQUIREMENTS BY COMPONENT a FENESTRATION U-FACTOR SKYLIGHT U- FACTOR b GLAZED FENESTRATION SHGC CEILING WOOD FRAME WALL d FLOOR BASEMENT WALL SLAB & DEPTH c CRAWL SPACE WALL CLIMATE - SUB CLIMATE ZONE 2.2 MAX GLAZED AREA TO WALL AREA RATIO MAX GLAZED FENESTRATION U-FACTOR TABLE EQUIVALENT U-FACTORS a MAX SKYLIGHT U-FACTOR b MAX GLAZED FENESTRATION SHGC MIN CEILING MIN WOOD FRAME WALL d MIN FLOOR MIN BASEMENT WALL Fig. 10 Zero Energy design guidelines 6

9 Austin Climate Data Glossary Subtropical Humid Climate: Characterized by hot, humid summers and cool winters. Subtropical Subhumid Climate: Characterized by hot, humid summers and cool, dry winters. Precipitation: Any or all of the forms of water droplets, whether liquid or solid, that fall from the atmosphere and reach the ground. Temperature: Register of the amount of heat contained by the air at surface and is measured in degrees on the Fahrenheit temperature scale by alcohol or mercury thermometers. Notes 1. publications/reports/groundwaterreports/ LimitedPublications/LP192.pdf ccd/avgwind.html 4. downloads/zeh_fact_sheet.pdf 5. citationguide.html Figures Figure 01: Figure 02: reports/groundwaterreports/ LimitedPublications/LP192.pdf Figure 03: asp Figure 05: Figure 06: Figure 07: Austin%20City/ Figure 08: compliance/monops/air/windroses/ausall.gif Figure 09: Figure 10: wams_item_attach.cfm?recordid=7329 Appendix A: htm References Reference 01: Reference 02: Austin%20City/ Reference 03: htm Reference 04: compliance/monops/air/windroses/ausall.gif Reference 05: azel.html Reference 06: php?wfo=ewx Figure 04: htm 7

10 UTSoA - Meadows Fellowship Seminar MONTHLY/ ANNUAL/AVERAGE PRECIPITATION AUSTIN TX ( ) ALL-TIME: JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC ANNUAL ALL-TIME: Maximum Maximum Average Average Median Median Minimum TRACETRACE Minimum SEASONAL Spring Summer Autumn Winter Annual SEASONAL TOTALS TOTALS AVERAGE MONTHLY/ANNUAL TEMPERATURE AUSTIN TX ( ) ALL-TIME: JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC ANNUAL ALL-TIME: Record Hi Record Hi Average Average Median Median Record Lo Record Lo SEASONAL Spring Summer Autumn Winter Annual SEASONAL AVERAGES AVERAGES Appendix A: Average temperature and precipitation for Austin, TX. (Data taken at Camp Mabry) 8

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