Re: [EnergyPlus_Support] Surface:Shading:Detached:Building

["Michael J. Witte" <mjwitte@xxxxxxxx>]

Shading objects are Surface:Shading:Detached, 
Surface:Shading:Detached:Fixed, Surface:Shading:Detached:Building, 
and Surface:Shading:Attached.   

All of these shading surfaces produce the following effects:

a. They shade beam and diffuse solar from the sky, but they do NOT 
reflect either beam or diffuse solar. Some day we'll add solar 
reflection from other buildings, especially when they have lots of 
glass, to E+. (see Engineering Reference, p. 38) 

b. They shade long-wave radiation from the sky.  (see Engineering Reference, p. 39)

c. They emit long-wave radiation assuming, like the ground, that they 
have emissivity = 0.9 and temperature = air temperature. Since the 
sky temperature is generally less than the air temperature, there 
will be more long-wave from the shading surfaces (which could 
represent other buildings) than there would be from the portion of 
the sky they are shadowing. In this sense the other buildings are 
heat sources. However, assuming they are at the same temperature as 
the air can be a poor assumption if they are sunlit. The same applies 
to the ground. If the ground is hot asphalt it can get up to 130F or 
higher and radiate like mad.  

d. They do not reflect long-wave radiation from the ground, sky, target
building, or anything else.

There is also another input which is related to the presence of 
surrounding buildings.  In the BUILDING object, the Terrain field can 
be set to FlatOpenCountry, RoughWoodedCountryTownsSuburbs, or 
CityCenter.  This field alters the windspeed value which is used to 
calculate exterior convection coefficients.  See pp. 7-8 in the Input 
Output Reference.  

Mike Witte (with much help from Fred Winkelmann)


On 18 Sep 2002, at 11:44, rmp4aup6 wrote:

> A simple question about shading surface.
> 
> In Energyplus, we talked about the shading effects from attached and
> detached surfaces, including the surrounding buildings around the
> building we want to simulate.
> 
> In that case, does E+ assume that the surrounding builings are not
> heat sources? (the surrounding buildings will not influence the
> temperature of the builidng we want to simulate) 
> 
> or E+ can simulate the heat balance which comes from the surrounding
> buildings? 
> 
> chunming
> 
> 
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