1 · the need
A daily value is not an hourly climate
The temperature mean does not say when the warmest hour occurs. A rainfall total does not say whether water arrives steadily or in a short burst. Building models respond to the sequence as well as the amount.
After 3DBC we have reconciled daily targets for variables. Step 3 must turn each day into 24 physically usable hours.
2 · two inputs
Future amount, historical shape
The reconciled model chain supplies the future daily mean, range, or total. The historical hourly reference supplies a real within-day pattern for the same location and time of year.
We do not invent a smooth “typical day.” We reuse observed-reanalysis patterns already aligned with the location’s historical daily climate.
3 · pairing
Thirty reference years meet thirty future years
Each future window contains thirty years, matching the reference. After the 3DBC ordering, future days are paired positionally with their corresponding reference days and inherit those hourly patterns.
This shared reference chronology is intentional. The daily climate signal comes from each model chain; the sub-daily timing comes from the reference.
4 · reconstruction
Morph the pattern to the target
For each day, the operator keeps the useful shape of the hourly template while changing its level, amplitude, or total to follow the future daily target. The operation depends on the physical variable.
There is no single universal “daily-to-hourly” equation. Temperature, precipitation, humidity and radiation have different constraints.
5 · variable rules
Preserve what matters for each variable
Temperature is scaled and recentered around its future mean and daily range. Precipitation normally rescales the reference wet-hour pattern; newly wet days and unsuitable near-dry patterns receive explicit fallback shapes. Humidity carries a bounded dryness pattern coupled to future temperature. Shortwave radiation follows daylight and the available solar envelope.
Wind speed, pressure and longwave radiation use their own daily scaling or anomaly rules. Wind direction and solar geometry are carried from the reference chronology.
6 · constraints
Check the hours against the day
The reconstructed hours are aggregated back onto the variable’s original daily clock. The result is checked against the accepted future target and against physical limits such as non-negative precipitation, daylight, and relative humidity between 0 and 100%.
Daily conservation is the design goal. When an extreme target conflicts with a physical envelope or a safety cap, the intervention is recorded rather than hidden.
7 · output
A complete simulation climate
One model chain and one future period become consecutive hourly rows: no-leap years with hours each. The result can be delivered as hourly data or a building-simulation format.
We repeat the same construction for both future periods and all model chains.
8 · interpretation
Future loading, not future event chronology
The files are intended for long-term hygrothermal loading and comparative building simulations. They represent changed daily climate acting through realistic hourly patterns.
They do not predict the timing of a future storm or heatwave, reproduce a model’s future synoptic sequence, project a change in wind direction, or independently impose future sub-daily rainfall intensification.
Suitability depends on the failure mechanism. Long-term heat and moisture loading may be represented adequately even when individual hours differ, while threshold crossings, rainfall intermittency, rapid transitions and high-intensity events demand greater caution.