4.3 DESCOND
Specifies conditions for a cooling design day. When referenced in TOP coolDsCond (see TOP Autosizing), DESCOND members are used to generate a 24 hour design day used during cooling autosizing. Note that coolDsCond can reference more than one DESCOND, allowing multiple design conditions to be used for autosizing. For example, both summer and fall days could be specified to ensure a range of sun angles are considered. Any DESCONDs that are not referenced in coolDsCond have no effect.
desCondName
Object name, given after “DESCOND”. Required for referencing from Top coolDsCond.
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| 63 characters | none | Yes | constant |
dcDay=date
Calendar date for this design cooling condition.
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| 1-365 | 200 | No | constant |
dcDB=float
Design dry-bulb temperature (maxiumum temperature on design day).
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| oF | no-limitations? | 0.0 | No | constant |
dcMCDBR=float
Coincident daily dry-bulb range.
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| oF | no-limitations? | none | No | constant |
dcMCWB=float
Coincident wet-bulb design temperature.
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| oF | no-limitations? | none | No | constant |
dcMCWBR=float
Coincident daily wet-bulb range.
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| oF | no-limitations? | none | No | constant |
dcWindSpeed=float
Wind speed for design conditions.
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| mph | x \(\geq\) 0 | 0.0 | No | constant |
DESCOND provides two mutually-exclusive methods for specifying design day direct beam and diffuse horizontal irradiance values. Both use the ASHRAE clear sky model. Consult the ASHRAE Handbook of Fundamentals Climatic Data chapter for model documentation.
- Pseudo optical depth. dcTauB and dcTauD define the taub and taud parameters in the clear sky model.
- Solar noon irradiance. CSE uses dcEbnSlrNoon and dcEdhSlrNoon to back-calculate taub and taud.
At most one of these methods can be used within a given DESCOND. If all solar-related values are omitted, the generated design day has 0 irradiance for all hours.
dcTauB=float
dcTauD=float
ASHRAE clear sky model beam and diffuse pseudo optical depths. These values are available by month for many locations in ASHRAE design weather data. Cannot be given if dcEbnSlrNoon and dcEdhSlrNoon are specified.
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| 0 irradiance | No | constant |
dcEbnSlrNoon=float
dcEdhSlrNoon=float
Solar noon direct beam and diffuse horizontal irradiance. Cannot be given if dcTauB and dcTauD are specified.
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| Btuh/ft2 | x \(\geq\) 0 | 0 irradiance | No | constant |
endDesCond
Optionally indicates the end of the descond definition.
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| none | No |