Difference between PMV and ADP

Hello everyone,

I am writing a thesis and at the end I would like to conclude which one is more useful in some conditions, between the PMV and the ADP.
Generally the range of values of the indoor PMV is contained in -3 / + 3, while the one for the outdoor has no ranges. And what about ADP? I can’t find something useful about this on internet, could someone better explain the differences?
Furthermore, in my simulations I can get really extreme numbers in the final values that go beyond the -3 / + 3 range, even reaching 11 with ADP. If there are also documents relating to PMV and ADP describing the main differences, they are welcome!

ADP? I’m guessing the AD stands for “Adaptive” but what does the “P” mean?

There are no hard and fast rules about when a given thermal comfort model is no longer appropriate for a given situation but, generally speaking, PMV should be used exclusively for the indoors of fully-conditioned buildings and the Adaptive comfort model should be used exclusively for the indoors of naturally ventilation buildings. Neither of these two models was developed with data from humans in outdoor conditions so they should not be used to assess outdoor comfort. Or at least they should not be used when we have much better models for outdoor thermal comfort like UTCI.

Yes, I mean the Adaptive model, sorry. So is there no limitation range in the AD, like PMV (-3/+3)?

Hi Rhynoxas,

Are you able to get a copy of ASHRAE 55, CIBSE TM52, or EN 15251?

I think ASHRAEs would be particularly useful to you.

CIBSEs approach is that PPD <10% equates to ±3K applied to the neutral temperature from the adaptive method. CIBSE then sets exceedance limits to this with hourly, daily, and seasonal criteria (against a warm year weather file).

In general I’d advise you look more at the temperatures than the condition result, a score of 11 sounds like a very high temp. Worth noting the adaptive criteria only apply to a running mean temp of roughly 10-30degC (varies between ASHRAE and CIBSE).

Cheers,
Charlie

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Thank you so much Charlie, I’ll gladly take a look at the ASHRAEs.

Hi!

One additional question, I would like to calculate the number hours below the 20% PPD limit. I saw in the documentation that this is taken into account in ladybug adaptive comfort module:

ladybug_comfort.adaptive. ashrae55_neutral_offset_from_ppd (ppd=90 )[source]

Get acceptable offset from neutral temperature given the ASHRAE-55 PPD limit.
Parameters
ppd – The acceptable limit of Percentage of People Dissatisfied (PPD). Usually, this is 90% but it can be 80% in some cases.

Returns
offset – Acceptable temperature offset from neutral temperature [C]

I cannot find the component in LBT with an input “ashrae55_neutral_offset_from_ppd”:

  1. Is this parameter already included by default in the component Adaptive comfort parameters ?
  2. If yes, is this limit parameter also included when switching to the EN 15251?

Hi @mkdg,

Interesting, the wording here is wrong as far as I can tell so worth @chris being aware - rather than PPD it should be “acceptability limit”. I thought an acceptability limit of 80% equates to a PPD of 20% but looking through ASHRAE 55 2020 I can’t see that stated anywhere, which makes me think ASHRAE are trying to separate PPD from the adaptive comfort approach.

Looking in ASHRAE 55 the default should be an acceptability limit of 80%, not 90%. 80% equates to a temperature band of 7 (21.3-14.3 = 7), so 3.5degC above or below the “comfort temperature” (I might be using the wrong term there).

For EN15251 there are comfort classes defined. Normal expectation is ±3degC.(Note the image below is from CIBSE TM52, but it’s supposed to be implementing the same comfort classes and EN15251 and it’s a nicer image)

Looking at the Adaptive Comfort Parameter component the way to control this is through the neutral offset. ASHRAE 55 2.5degC would be 90% acceptability, 3.5degC would be 80% acceptability.

image

Hope that helps!

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Thank you charlie for the clear response! :slight_smile: