Station, source, window, method and lineage for the assumed outdoor dew point of 24 °C.
The model fixes the outdoor dew point at 24 °C and states that this value is drawn from the Dubai International station record for June to September (median 23.1 °C, 95th percentile 28.0 °C). This note sets out where those numbers come from and how they were computed, so that a consultant or project team can reproduce them.
| Item | Value |
|---|---|
| Station | Dubai International |
| WMO identifier | 41194 |
| ICAO identifier | OMDB |
| Item | Convention |
|---|---|
| Data period | 1 January 1995 to 31 December 2024. Thirty complete calendar years, the same for every station. |
| Dataset | Meteostat hourly bulk data (decimal-resolution temperature and dew point), compiled from the NOAA NCEI Integrated Surface Database. Retrieved 31 Aug 2026 (41194) and 4 Sep 2026 (the other stations). Licence CC BY 4.0, with attribution to Meteostat. |
| Observations used | Every hour with a valid dew point. No gap filling and no interpolation. Timestamps in UTC. |
| "Share of hours above X" | Strictly greater than X (for example > 22.0 °C), counted over all valid hours pooled across the period. |
| Percentiles | Nearest-rank, over all valid hours in the window. |
| "June to September" | All hours in June, July, August and September, pooled. |
| Rounding | Dew points to 0.1 °C. Shares to 0.1 percentage point in the technical note. Prose may round to a fraction ("one hour in four") only when the exact value is within ±1.5 points of that fraction. |
| Dew point formula | Magnus, Alduchov and Eskridge (1996) coefficients: 17.625, 243.04 °C, 610.94 Pa. |
Sensitivity of the Dubai International share of hours above 22 °C:
The statistics below should therefore be quoted with their source named, as they are on the research page.
| Item | Value |
|---|---|
| Months | June, July, August, September (inclusive), every year from 1995 to 2024 |
| Observations | All hourly observations in the window; no sub-sampling by hour of day |
| Sample size | n = 84,959 hours |
| Missing data | Hours with no dew-point value are excluded; no interpolation or infilling is applied |
| Statistic | Value | Method |
|---|---|---|
| Median dew point | 23.1 °C | 50th percentile, nearest rank, over all hours in the window |
| 95th percentile dew point | 28.0 °C | 95th percentile, nearest rank, over all hours in the window |
| Hours with dew point above 24 °C | 39.6 % | Count of hours with Tdp > 24 °C divided by n |
| Hours with dew point above 22 °C | 59.2 % | Count of hours with Tdp > 22 °C divided by n |
Percentiles are computed by rank over the pooled hourly values (no weighting by year, no seasonal averaging first). 24 °C lies between the median and the 95th percentile and is exceeded in 39.6 % of June–September hours. A cooled interior held at 24 °C therefore sits below the outdoor dew point for roughly four hours in ten across the season, which is the basis for the model's fixed outdoor value and for the wording of FAQ 4 on the research page.
The model treats room pressure as direction only. When the room is depressurized relative to outdoors, the infiltration readout names the outdoor dew point of 24 °C as what arrives through leakage paths in the exposed face. The quantity of moisture moved depends on envelope leakage and is not computed; it must be measured on site.
The home page states that "for one hour in four" the outdoor air in the coastal cities of the UAE, Dubai and Abu Dhabi among them, carries a dew point above 22 °C. Basis, same source and conventions as above, but all hours of the year rather than the June–September window:
| Statistic | Value | Window |
|---|---|---|
| Hours with dew point above 22 °C | 25.0 % | All valid hourly observations, 1995–2024 |
Six stations, 1 January 1995 to 31 December 2024: share of all hours with outdoor dew point above 22.0 °C, and the June–September median and 95th percentile.
| Station | ICAO | WMO | Valid hours | Coverage | Hours > 22 °C dew point | Jun–Sep median | Jun–Sep p95 |
|---|---|---|---|---|---|---|---|
| Dubai International | OMDB | 41194 | 254,554 | 96.8 % | 25.0 % | 23.1 °C | 28.0 °C |
| Abu Dhabi International | OMAA | 41217 | 255,982 | 97.3 % | 24.0 % | 23.0 °C | 28.8 °C |
| Ras Al Khaimah International | OMRK | 41184 | 248,830 | 94.6 % | 21.9 % | 22.2 °C | 28.0 °C |
| Sharjah International | OMSJ | 41196 | 253,568 | 96.4 % | 20.9 % | 22.1 °C | 27.4 °C |
| Fujairah International (east coast) | OMFJ | 41198 | 245,090 | 93.2 % | 38.7 % | 26.9 °C | 29.9 °C |
| Al Ain International (inland) | OMAL | 41218 | 251,598 | 95.7 % | 7.2 % | 17.2 °C | 25.1 °C |
Dubai Al Maktoum (OMDW, WMO 41216) is excluded. Its record is almost empty from 2001 to 2007 (69.3 % coverage), and the missing years would weight what remains.
"One hour in four" is used only where the exact share is within ±1.5 points of 25 %: Dubai International (25.0 %) and Abu Dhabi International (24.0 %), the two cities the home page names. Sharjah (20.9 %) is one hour in five, not one in four, and inland Al Ain (7.2 %) is fewer than one hour in ten, which is why the home page says "the coastal cities of the UAE, Dubai and Abu Dhabi among them" and not "the UAE".
The page carries only the rounded phrase "one hour in four"; the percentages above are the computed basis and are not to be quoted more precisely than stated here.