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Re: [TRNSYS-users] ts15-type 56 effect of wind on heating load
Dear Xavier,
Wind effects on buildings are quite complex, depending on building
geometry, on wind speed, on wind direction, on penetrations through the
building envelope (doors, windows, etc.) and on local terrain (trees,
surrounding buildings, etc.). TRNSYS includes a number of methods for
estimating these effects. If all you want is a very basic estimation of
a wind speed dependent heat transfer coefficient, you can use the ASHRAE
equation:
h = a1 + a2*V + a3*V^2
where a1, a2, and a3 are in W/K.m2 and depend on the exterior surface
material. For stucco, a1 = 11.58, a2 = 5.894, and a3 = 0. For glass, a1
= 8.23, a2 = 3.33 and a3 = -0.036. (From ASHRAE Standard 140)
The next step up in complexity of predicting the effect of wind induced
infiltration is to use one of ASHRAE's simplified methods: either the
K1, K2, K3 approach, or the Sherman Grimsrud equation. There are
components in the TESS Utility Library that will calculate infiltration
using these methods.
The final level of complexity is to make use of standard TRNSYS Type157
(connection to COMIS) or Type97 (Connection to CONTAM). These components
provided data links between TRNSYS and two different airflow modelling
tools. There is some redundancy of data entry in that you have to
describe the building thermal model in TRNBuild, then describe the
building geometry in CONTAM or COMIS. Once defined, however, the
programs work together to do combined thermal / airflow modeling of the
building. COMIS is available as an add on to TRNSYS from CSTB. CONTAM is
freely available for the US National Institute of Standards and
Technologies (http://www.bfrl.nist.gov/IAQanalysis/CONTAMWdesc.htm). As
a final alternative, you can use another TRNSYS add-on called TRNFLOW.
TRNFLOW is an adaptation of COMIS. It is available from Transsolar and
provides a combined front end for the specification of both the airflow
and the thermal model inside TRNBuild.
Kind regards,
David
Xavier Dequaire wrote:
Hi,
type 56 does not take wind as an input,
Any method to simulate the effects of wind on the energy consumption of
the building?
thank you
Xavier D.
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David BRADLEY
Solar Energy Laboratory
University of Wisconsin - Madison
1500 Engineering Drive
Madison, WI 53706
United States
Ph: +1 608 263 1589
Fax: +1 608 262 8464
Email: dbradley@engr.wisc.edu