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Assessing Thermal Comfort credit BREEAM - Energy modelling

asked 2016-09-21 08:24:21 -0500

updated 2016-09-21 09:43:06 -0500


Does anyone ever made a study for BREEAM Thermal comfort credit? There isn't any methodology on their manual and I was wondering how everyone is doing it? Also, does anyone knows how trusty DesignBuilder can be for calculating Fanger PMV?

Thanks in advance,

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answered 2016-09-22 07:27:07 -0500

I see. So you determine the global PMV from an average (absolute or you sum positive and negative?) of the hourly PMV of design weeks (either summer or winter), right? So you get two average PMV: one for winter and the other for summer and then, the "worst" value between the two is the one put in BREEAM tool.

What I do: I assess zone by zone the PMV hourly during occupied hours. If 5% of the occupied hours are outside Category B (method A described in the Annex H of the norm ISO 7730:2005) then that zone is not compliant, and compliant if it is below 5%. Then I calculate an average PMV of the absolute value of the hourly PMV of the occupied hours. At the end if 95% of the spaces are compliant then the building is compliant and I determine the average PMV and PPD corresponding.

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Hi @NassimJ,

You say "If 5% of the occupied hours are outside Category B (method A described in the Annex H of the norm ISO 7730:2005) then that zone is not compliant, and compliant if it is below 5%". I cannot find reference to those 5% in ISO 7730.

They just say "Calculate the number or percentage of hours during the hours the building is occupied, the PMV or the operative temperature is outside a specified range."

May I ask where did you find reference to those 5%?

Thank you in advance for your time.

Fábio Batista's avatar Fábio Batista  ( 2018-08-03 09:39:18 -0500 )edit

Hi Fabio,

This is an interpretation of two norms: ISO 7730 and EN 15251.


NassimJ's avatar NassimJ  ( 2019-03-27 03:55:57 -0500 )edit

answered 2016-09-21 08:54:14 -0500

Vmoreno's avatar

Hi @NassimJ

I have carried out Thermal comfort calculations for BREEAM requirements using Desing Builder.

You have to carry out taking into account UNE EN ISO 7730:2006. You have to calculate the PMV and PPD levels for all conditioned zones of the building evaluated. And to demostrate that values obtained are compliance wtih category B of UNE ISO 7730.

Design Builder can calculate Fanger PMV without problems. You can see the following documentation:

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Hey Vmoreno,

Thanks for your reply. Yes I already know about the norm. Two things: 1- On methodology: How do you calculate the PMV and PPD for each room? (do you take into account the unoccupied hours or exclude them? Then do you calculate it hourly? daily? weekly?... And then how do you get to the overall building PMV and PPD? 2- About DB: Sometime, the operative temperature of the room is nearly 25-26°C, the RH 40-60% and the software still notify you that it is cold (PMV below -0.5). I guess, it takes in account the other parameter such as the air speed, but how to control it? Thanks :)

NassimJ's avatar NassimJ  ( 2016-09-22 02:15:43 -0500 )edit

I already assessed the Thermal Comfort Credit for a previous project. But I feel like I'm playing with a black box when it comes to calculate Fanger PMV on DesignBuilder and elaborating the methodology for BREEAM Credit. That is why i want to know how the other energy modeller are tackling this analysis! So we can cross our knowledge :)

NassimJ's avatar NassimJ  ( 2016-09-22 02:19:28 -0500 )edit

Hi @NassimJ.

I calculate PMV and PPD indexes for every hours (only summer and winter extremely week), but I evaluate only occupied hours. I calculate it hourly and calculate the mean for summer extremely week and winter extremely week. i input the valou more restrictive in BREEAM tool. The air velocity doesn´t calculate by Energy Plus, but you can use CFD module for calculate velocity vector. However, with E+ calculation you can comply this BREEAM credit.

You have to evaluate air temperature and radiant temperature, doesn´t operative temperature.

Vmoreno's avatar Vmoreno  ( 2016-09-22 02:54:52 -0500 )edit

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Asked: 2016-09-21 08:24:21 -0500

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Last updated: Sep 22 '16