The HMS only effects the heating system's response to cold outdoor air temperature (heating degree days
) while other building characteristics, such as the occupancy rate and thermal response, had minimal variations after the retrofit, so a two-parameter model using heating degree days
Where [HDD.sub.r] and [CDD.sub.r] are monthly heating degree days
and cooling degree days respectively for region r.
Roback  found that heating degree days
, total snowfall, and the number of cloudy days were positively correlated with wages, suggesting these are disamenities.
In principle we could simply find the ratio of energy usage to heating degree days
using on-site weather data, and multiply by the HDD associated with the TMY3 file (See Equation 1).
Where [HDD.sub.i] and [CDD.sub.i] are monthly heating degree days
and cooling degree days respectively for region i where regions are defined as the area served by a particular power distribution company, in this case, KESC, [T.sub.i], is the monthly average temperature of region i, [T.sub.b] is the base temperature, m is the number of days in the month under consideration, y is a binary variable that equals 1 if [T.sub.1] < [T.sub.b] and 0 otherwise.
An example of a building striving towards net zero space heating is the recently completed Material Testing Laboratory (MTL) in Hamilton, Ontario (3600 annual Celsius heating degree days
[[beta].sub.h] = daily consumption per heating degree day
LOGAN, IA: Monthly total heating degree days
, [online] [cited 05 October 2012].
There were 20 percent fewer heating degree days
in the first half of 2012 than in the first half of 2011, Unitil said.
Double-cropping is not used in this area, generally because there are too little heating degree days
. However, a recent study of the last ten years' heating degree days
showed that 80-day hybrids harvested at 35% to 40% moisture content will allow for double-cropping of corn as far north as northern Illinois.
Lower gas therm sales in the Company's utility service territories reflect the effect of warmer temperatures in 2010, where there were approximately 22% and 12% fewer Heating Degree Days
in the the three and six month periods, respectively, compared to the prior year.
Riker says the company already has created more than 500 customized indexes for five industries, based on weather correlations over specific time periods to benchmarks such as heating degree days
. North America is the focus now, he says, and expansion to global markets "will be limited to where there is good weather data."