Heating and Cooling Degree-Day’s distribution on Mendoza’s Metropolitan Area

The differences between the values of HDD and CDD obtained from the different of measurement sites (urban and rural stations within MMA and the local weather station at the airport) were calculated. These differences were expressed as percentages in order to quantify the error’s magnitude incurred in the calculation of the studied variables when not considering the effect of the city on the local climate.

Table 3. Monthly values of HDD y CDD corresponding to the north transect. Stations 50 vs. 59 and the

Airport’s station are compared. (See figure 1)

Urban Area

Rural Area

Airport

Difference %

CDD

HDD

CDD

HDD

CDD

HDD

U-R

U-A

R-A

January

247

212

226

17%

9%

-6%

February

191

143

178

34%

7%

-20%

March

82

49

76

68%

9%

-35%

April

50

127

100

-61%

-50%

27%

May

142

235

183

-40%

-22%

28%

June

178

310

267

-43%

-33%

15%

July

225

331

282

-32%

-20%

17%

August

200

279

248

-28%

-19%

12%

September

80

178

162

-55%

-50%

10%

October

54

26

0

107%

November

185

146

174

26%

6%

-15%

December

315

228

220

38%

43%

4%

Table 4. Monthly values of HDD y CDD corresponding to the south transect. Stations 50 vs. 40 and the

Airport’s station are compared. (See figure 1)

Urban Area

Rural Area

Airport

Difference %

CDD

HDD

CDD

HDD

CDD

HDD

U-R

U-A

R-A

January

247

180

226

37%

9%

-20%

February

191

127

178

50%

7%

-28%

March

82

40

76

86%

9%

-41%

April

50

131

100

-62%

-50%

31%

May

142

243

183

-42%

-22%

32%

June

178

236

267

-25%

-31%

8%

July

225

337

282

-41%

-20%

17%

August

200

291

248

-39%

-19%

17%

September

80

122

162

-34%

-50%

25%

October

54

23

0

134%

November

185

146

174

27%

6%

-16%

December

315

217

220

45%

43%

-1.5%

Table 5. Monthly values of HDD y CDD corresponding to the west transect. Stations 50 vs. 3 and the

Airport’s station are compared. (See figure 1)

Urban Area

Rural Area

Airport

Difference %

CDD

HDD

CDD

HDD

CDD

HDD

U-R

U-A

R-A

January

247

176

226

40%

9%

-22%

February

191

132

178

44%

7%

-26%

March

82

52

76

60%

9%

-31%

April

50

94

100

-47%

-50%

6%

May

142

219

183

-35%

-22%

19%

June

178

287

267

-38%

-33%

7%

July

225

301

282

-25%

-20%

6%

August

200

290

248

-31%

-19%

17%

1st International Congress on Heating, Cooling, and Buildings, 7th to 10th October, Lisbon — Portugal /

September

80

120

162

-33%

-50%

-26%

October

54

23

0

134%

November

185

142

174

30%

6%

-18%

December

315

195

220

61%

43%

-11%

Table 6. Monthly values of HDD y CDD corresponding to the east transect. Stations 50 vs. 15 and the

Airport’s station are compared. (See figure 1)

Urban Area

Rural Area

Airport

Difference %

CDD

HDD

CDD

HDD

CDD

HDD

U-R

U-A

R-A

January

247

217

226

14%

9%

-4%

February

191

170

178

12%

7%

-4%

March

82

60

76

37%

9%

-20%

April

50

89

100

-44%

-50%

11%

May

142

201

183

-29%

-22%

9%

June

178

263

267

-32%

-33%

2%

July

225

279

282

-19%

-20%

-1%

August

200

259

248

-23%

-19%

4%

September

80

96

162

-17%

-50%

-40%

October

54

23

0

134%

November

185

147

174

26%

6%

-15%

December

315

164

220

92%

43%

-25%

The results show that during summer time there exists an underestimation in the cooling demand calculated from the data obtained by local weather stations that oscillates between 6% and 43%. For the winter time, it happens oppositely, an overestimation of the heating load that represents an error from about 19% to 50%.

In the case of the air temperature behavior in downtown respect to its surroundings, it is observed that the demand for cooling in the downtown area is higher than 12% and up to a 130% respect to the surroundings demands, depending on the month of a year and the zone of the city analyzed.

The demand of heating for downtown area respect to the environs is smaller in the order of 25 to 62%.The energy requirements of the suburban and rural zones of the city respect to the values calculated from the local weather station show an overestimation of 4% to 41% of the cooling necessities, and an underestimation of 2% to 32% in the case of the heating demand.

Figure 3 shows the yearly distribution of HDD and CDD within the AMM. The degree day’s distribution responds clearly to the thermal behavior and to the climatic conditions that prevail in the city. During the summer the radiation levels are high, for this reason the materials that compose the ground of the city’s out-skirts, which are mainly rocky, accumulate heat during the day, homogenizing the distribution of temperatures between downtown area and the city’s out-skirts of the. This does not happen in winter due to the lesser amount of radiation during the day, increasing the temperature differences between downtown and the rural areas.

The greater demand in refrigeration during the month of December can be explained by the increase of the anthropogenic contribution in the city, because this is a festive month, whereas January and February are months of vacations. The maps that show the distribution of heating and cooling degrees-day within the AMM always display a hot zone of greater demand of refrigeration and minor demand of heating coincident with the administrative-commercial zone in the city.

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