I am trying to calculate heating/cooling degree day using (Tbase - Ta) formula Tbase is usually 65F and Ta = (high_temp + low_temp)/2
(example)
high_temp = 96.5F low_temp=65.21F then
mean=(high_temp + low_temp)/2
result = mean - 65
65 is average room temperature
if result is > 65 then cooling degree day (cdd) else heating degree day (hdd)
I get weather data from two API:
In weatherbit the provide both cdd and hdd data, but in darksky we need to calculate using above formula (Tbase - Ta)
My problem is both API show different result (example)
darksky JSON response for day:
{
"latitude": 47.552758,
"longitude": -122.150589,
"timezone": "America/Los_Angeles",
"daily": {
"data": [
{
"time": 1560927600,
"summary": "Light rain in the morning and overnight.",
"icon": "rain",
"sunriseTime": 1560946325,
"sunsetTime": 1561003835,
"moonPhase": 0.59,
"precipIntensity": 0.0057,
"precipIntensityMax": 0.0506,
"precipIntensityMaxTime": 1561010400,
"precipProbability": 0.62,
"precipType": "rain",
"temperatureHigh": 62.44,
"temperatureHighTime": 1560981600,
"temperatureLow": 48,
"temperatureLowTime": 1561028400,
"apparentTemperatureHigh": 62.44,
"apparentTemperatureHighTime": 1560981600,
"apparentTemperatureLow": 46.48,
"apparentTemperatureLowTime": 1561028400,
"dewPoint": 46.61,
"humidity": 0.75,
"pressure": 1021.81,
"windSpeed": 5.05,
"windGust": 8.36,
"windGustTime": 1560988800,
"windBearing": 149,
"cloudCover": 0.95,
"uvIndex": 4,
"uvIndexTime": 1560978000,
"visibility": 4.147,
"ozone": 380.8,
"temperatureMin": 49.42,
"temperatureMinTime": 1561010400,
"temperatureMax": 62.44,
"temperatureMaxTime": 1560981600,
"apparentTemperatureMin": 47.5,
"apparentTemperatureMinTime": 1561014000,
"apparentTemperatureMax": 62.44,
"apparentTemperatureMaxTime": 1560981600
}
]
},
"offset": -7
}
python calculation
response = result.get("daily").get("data")[0]
low_temp = response.get("temperatureMin")
hi_temp = response.get("temperatureMax")
mean = (hi_temp + low_temp)/2
#65 is normal room temp
print(65-mean)
Here mean is 6.509999999999998
65 - mean = 58.49
hdd is 58.49 so cdd is 0
Same date in weatherbit JSON response is:
{
"threshold_units": "F",
"timezone": "America/Los_Angeles",
"threshold_value": 65,
"state_code": "WA",
"country_code": "US",
"city_name": "Newcastle",
"data": [
{
"rh": 68,
"wind_spd": 5.6,
"timestamp_utc": null,
"t_ghi": 8568.9,
"max_wind_spd": 11.4,
"cdd": 0.4,
"dewpt": 46.9,
"snow": 0,
"hdd": 6.7,
"timestamp_local": null,
"precip": 0.154,
"t_dni": 11290.6,
"temp_wetbulb": 53.1,
"t_dhi": 1413.9,
"date": "2019-06-20",
"temp": 58.6,
"sun_hours": 7.6,
"clouds": 58,
"wind_dir": 186
}
],
"end_date": "2019-06-21",
"station_id": "727934-94248",
"count": 1,
"start_date": "2019-06-20",
"city_id": 5804676
}
here hdd is 6.7 and cdd is 0.4
Can you explain how they get this result?
You need to use hourly data to calculate the HDD and CDD, and then average them to get the daily value.
More details here: https://www.weatherbit.io/blog/post/heating-and-cooling-degree-days-weather-api-release