[esp-r] Re: radiant and convective split for occupants

[Achim.geissler]

Hi Jon

there is, of course, no single pair of numbers. The distribution highly
depends on surroundings, activity rate and clothing level.

As CIBSE Guide A (chapter 6.3) states, "between 20 and 60% of the sensible
heat emission can be radiant depending on type of clothing, activity, mean
radiant temperature and air velocity".

The ASHRAE Fundamentals have an extensive chapter on Physiological
Principles and Thermal Comfort and give equations for the various heat
transfer mechanisms.

For "sedentiary office work", I have a (german) source that gives approx. 40
% radiative at 20 °C and approx 32 % radiative at 26 °C office temperatures
(with total sensible heat loss of 90 and 70 W, respectively - the total
value is approx. 120 W for both temperatures). Interestingly, this source
discerns between radiative, conductive and convective. But the conductive
part is only approx. 8 - 10 % and is probably usually added to the
convective part.

Best
Achim



--------- Original-Nachricht --------
 Von: "Jon Hand" 
 An: "esp-r at lists.strath.ac.uk" 
 Betreff: [esp-r]  radiant and convective split for occupants
 Datum: 14/12/10 10:23
 
 
 I am updating some documentation about occupants in buildings related to
 the radiant and convective split of sensible gains and I find that there
are
 a number of exemplar models that simply default to 50% radiant.  If I look
 at the exemplar models that come with EnergyPlus I see most of them
 are setting the radiant fraction of occupants to 30% and at least one
 paper  mentioned 40%.
 
 A Google search comes up with suggestions for what the sensible
 is but mentions of how it is distributed seem to be well hidden.  In
densely
 populated spaces this must have an impact.
 
 Does anyone have some or know about ...
  a) opinions that they would like to share
  b) some references that discuss this
  c) some papers that talk about it
 
 Regards, Jon Hand
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