Convert DeST climate data to an EnergyPlus weather object

to_epw() converts the selected CLIMATE_DATA hourly series in a DeST model to an eplusr Epw object. The returned object stays in memory; call its $save() method to write an EPW file.

Usage

to_epw(dest, radiation_time = c("centered", "hour_start", "auto"))

Arguments

dest

A DBI connection, a path to a SQLite database produced by read_dest(), or a path to a DeST Access .accdb/.mdb file.

radiation_time

Solar interval represented by each source radiation record. "centered" (the existing default approximation) uses [HOUR - 0.5, HOUR + 0.5]. "hour_start" uses [HOUR, HOUR + 1], for hourly interval data imported with zero-based hour indices, such as the ASHRAE 140 TF models prepared from TMY3. "auto" evaluates both intervals and selects one only when it alone passes the sunlight and DNI checks. If both pass or both fail, conversion stops with both diagnostics. Explicit choices should follow source provenance.

Value

An eplusr::Epw object. The destep_audit attribute records input repairs and radiation diagnostics.

Details

DNI is estimated from horizontal beam radiation and the mean positive sine of solar altitude over the selected interval. GHI and DHI alone do not uniquely recover measured hourly DNI; the estimate assumes constant DNI during the sunlit part of the interval. No radiation values are shifted or interpolated, and output rows retain the EPW hours 1 through 24. The centered convention retains the existing conversion approximation; its solar support is half an hour earlier than the EPW record interval. Inconsistent positive beam radiation without sunlight and DNI above 1500 W/m2 are rejected rather than discarded or clipped.

Automatic selection is an inference from physical consistency, not proof of the source timestamp definition. It never selects the smaller DNI or the candidate with fewer failures. With no discriminating radiation (including an all-zero year), both candidates can pass and an explicit choice is needed. The audit records the requested and selected conventions, selection reason, and candidate diagnostics. Automatic-selection errors inherit from destep_radiation_time_error and expose these diagnostics as $candidates.