Maximum solar heat gain factors for sunlighted glass in north latitudes
From ASHRAE (1989), with permission
Latitude | Month | Btu/hr·ft2 for given orientation | |||||
N |
NE/NW |
E/W |
SE/SW |
S |
HOR |
||
0° |
Jan |
34 |
88 |
234 |
235 |
118 |
296 |
Feb |
36 |
132 |
245 |
210 |
67 |
306 |
|
Mar |
38 |
170 |
242 |
170 |
38 |
303 |
|
Apr |
71 |
193 |
221 |
118 |
37 |
284 |
|
May |
113 |
203 |
201 |
80 |
37 |
265 |
|
Jun |
129 |
206 |
191 |
66 |
37 |
255 |
|
Jul |
115 |
201 |
195 |
77 |
38 |
260 |
|
Aug |
75 |
187 |
212 |
112 |
38 |
276 |
|
Sep |
40 |
163 |
231 |
163 |
40 |
293 |
|
Oct |
37 |
129 |
236 |
202 |
66 |
299 |
|
Nov |
35 |
88 |
230 |
230 |
117 |
293 |
|
Dec |
34 |
71 |
226 |
240 |
138 |
288 |
|
8° |
Jan |
32 |
71 |
224 |
242 |
162 |
275 |
Feb |
34 |
114 |
239 |
219 |
110 |
294 |
|
Mar |
37 |
156 |
241 |
184 |
55 |
300 |
|
Apr |
44 |
184 |
225 |
134 |
39 |
289 |
|
May |
74 |
198 |
209 |
97 |
38 |
277 |
|
Jun |
90 |
200 |
200 |
82 |
39 |
269 |
|
Jul |
77 |
195 |
204 |
93 |
39 |
272 |
|
Aug |
47 |
179 |
216 |
128 |
41 |
282 |
|
Sep |
38 |
149 |
230 |
176 |
56 |
290 |
|
Oct |
35 |
112 |
231 |
211 |
108 |
288 |
|
Nov |
33 |
71 |
220 |
233 |
160 |
273 |
|
Dec |
31 |
55 |
215 |
247 |
179 |
265 |
|
Latitude | Month | Btu/hr·ft2 for given orientation | |||||
N |
NE/NW |
E/W |
SE/SW |
S |
HOR |
||
16° |
Jan |
30 |
55 |
210 |
251 |
199 |
248 |
Feb |
33 |
96 |
231 |
233 |
154 |
275 |
|
Mar |
35 |
140 |
239 |
197 |
93 |
291 |
|
Apr |
39 |
172 |
227 |
150 |
45 |
289 |
|
May |
52 |
189 |
215 |
115 |
41 |
282 |
|
Jun |
66 |
194 |
207 |
99 |
41 |
277 |
|
Jul |
55 |
187 |
210 |
111 |
42 |
277 |
|
Aug |
41 |
168 |
219 |
143 |
46 |
282 |
|
Sep |
36 |
134 |
227 |
191 |
93 |
282 |
|
Oct |
33 |
95 |
223 |
225 |
150 |
270 |
|
Nov |
30 |
55 |
206 |
247 |
196 |
246 |
|
Dec |
29 |
41 |
198 |
254 |
212 |
234 |
|
24° |
Jan |
27 |
41 |
190 |
253 |
227 |
214 |
Feb |
30 |
80 |
220 |
243 |
192 |
249 |
|
Mar |
34 |
124 |
234 |
214 |
137 |
275 |
|
Apr |
37 |
159 |
228 |
169 |
75 |
283 |
|
May |
43 |
178 |
218 |
132 |
46 |
282 |
|
Jun |
55 |
184 |
212 |
117 |
43 |
279 |
|
Jul |
45 |
176 |
213 |
129 |
46 |
278 |
|
Aug |
38 |
156 |
220 |
162 |
72 |
277 |
|
Sep |
35 |
119 |
222 |
206 |
134 |
266 |
|
Oct |
31 |
79 |
211 |
235 |
187 |
244 |
|
Nov |
27 |
42 |
187 |
249 |
224 |
213 |
|
Dec |
26 |
29 |
180 |
247 |
237 |
199 |
|
Latitude | Month | Btu/hr·ft2 for given orientation | |||||
N |
NE/NW |
E/W |
SE/SW |
S |
HOR |
||
32° |
Jan |
24 |
29 |
175 |
249 |
246 |
176 |
Feb |
27 |
65 |
205 |
248 |
221 |
217 |
|
Mar |
32 |
107 |
227 |
227 |
176 |
252 |
|
Apr |
36 |
146 |
227 |
187 |
115 |
271 |
|
May |
38 |
170 |
220 |
155 |
74 |
277 |
|
Jun |
44 |
176 |
214 |
139 |
60 |
276 |
|
Jul |
40 |
167 |
215 |
150 |
72 |
273 |
|
Aug |
37 |
141 |
219 |
181 |
111 |
265 |
|
Sep |
33 |
103 |
215 |
218 |
171 |
244 |
|
Oct |
28 |
63 |
195 |
239 |
215 |
213 |
|
Nov |
24 |
29 |
173 |
245 |
243 |
175 |
|
Dec |
22 |
22 |
162 |
246 |
252 |
158 |
|
40° |
Jan |
20 |
20 |
154 |
241 |
254 |
133 |
Feb |
24 |
50 |
186 |
246 |
241 |
180 |
|
Mar |
29 |
93 |
218 |
236 |
206 |
223 |
|
Apr |
34 |
140 |
224 |
203 |
154 |
252 |
|
May |
37 |
165 |
220 |
175 |
113 |
265 |
|
Jun |
48 |
172 |
216 |
161 |
95 |
267 |
|
Jul |
38 |
163 |
216 |
170 |
109 |
262 |
|
Aug |
35 |
135 |
216 |
196 |
149 |
247 |
|
Sep |
30 |
87 |
203 |
226 |
200 |
215 |
|
Oct |
25 |
49 |
180 |
238 |
234 |
177 |
|
Nov |
20 |
20 |
151 |
237 |
250 |
132 |
|
Dec |
18 |
18 |
135 |
232 |
253 |
113 |
|
Latitude | Month | Btu/hr·ft2 for given orientation | |||||
N |
NE/NW |
E/W |
SE/SW |
S |
HOR |
||
48° |
Jan |
15 |
15 |
118 |
216 |
245 |
85 |
Feb |
20 |
36 |
168 |
242 |
250 |
138 |
|
Mar |
26 |
80 |
204 |
239 |
228 |
188 |
|
Apr |
31 |
132 |
219 |
215 |
186 |
226 |
|
May |
35 |
158 |
218 |
192 |
150 |
247 |
|
Jun |
46 |
165 |
215 |
180 |
134 |
252 |
|
Jul |
37 |
156 |
214 |
187 |
146 |
244 |
|
Aug |
33 |
128 |
211 |
208 |
180 |
223 |
|
Sep |
27 |
72 |
191 |
228 |
220 |
182 |
|
Oct |
21 |
35 |
161 |
233 |
242 |
136 |
|
Nov |
15 |
15 |
115 |
212 |
240 |
85 |
|
Dec |
13 |
13 |
91 |
195 |
233 |
65 |
|
56° |
Jan |
10 |
10 |
74 |
169 |
205 |
40 |
Feb |
16 |
21 |
139 |
223 |
244 |
91 |
|
Mar |
22 |
65 |
185 |
238 |
241 |
149 |
|
Apr |
28 |
123 |
211 |
223 |
210 |
195 |
|
May |
36 |
149 |
215 |
206 |
181 |
222 |
|
Jun |
53 |
160 |
213 |
196 |
168 |
231 |
|
Jul |
37 |
147 |
211 |
201 |
177 |
221 |
|
Aug |
30 |
119 |
203 |
215 |
203 |
193 |
|
Sep |
23 |
58 |
171 |
227 |
231 |
144 |
|
Oct |
16 |
20 |
132 |
213 |
234 |
91 |
|
Nov |
10 |
10 |
72 |
165 |
200 |
40 |
|
Dec |
7 |
7 |
47 |
135 |
171 |
23 |