PMV and PPD Thermal Analysis For BREEAM

[wyliecoyote]

Hello All,

I've a few questions I am hoping somebody may be able to shed light on. I'm looking to carry out PMV and PPD for BREEAM Hea 03: Thermal Comfort

1. I'm assuming the VE conforms to ISO:7730:2005

2. I've looked up IS0:7730:2005 and found how PMV is calculated. I can see that as part of the calculation we have to input a figure for the relative air velocity in m/s. If my building s fully air-conditioned should I be putting in around 0.25m/s as this is what is generally felt in the occupied zone?

I have seen that this can be input in vista under the comfort parameters.

2. Im assuming all my internal gains will have to be set as usual . i.e. lights, computers, etc etc with the profile assumed to be on continuously??

3. Do I need to bother setting up a system in apache or can I simply just state internal temps and the velocity of the air as mentioned above

Any other problems people may foresee would be greatly appreciated.

Many thanks in advance

[wyliecoyote]

I think ive answered my own question here.

But as far as i know all i should be concerned about it the room temp which i apply to each room and the clothing level, met level and air speed which can be obtained from CIBSE Guide A

[PCully]

Hi,

To assess comfort you'd have to build your model fully for a dynamic thermal simulation. This will include entering details of the internal gains, infiltration, vent air, HVAC system, set points, fabric etc for each room so that you can run the simulation and calculate room air temperatures.

Then you can assess whatever comfort criteria you have to ensure designs meet these standards e.g. most commonly if you have natural ventilation is it adequate during extreme summer months for the occupant comfort or does this need to be supplemented by some mechanical in worst cases.

As you have already noted there are comfort parameters built into VistaPro that you can assess and these variables will require some additional input form you for met and clo levels. Beyond that we also have some implementation for the CIBSE TM 52 assessments in VistaPro that will output a summary text report and additional variables. You can find a separate guide for this via Help >> User Guides in the Thermal category

Phil

[wyliecoyote]

Hi Phil,

Thanks for the reply.

Shouldn't it be efficient enough to just state the internal temperature i.e. set up a set point temperature (provided we can prove it can be achieved) for each room and put a system in to control it?

I also have one other final question you may be able to help with and its in relation to the radiant asymmetry.

I'm having problems trying to understand what values I should use for delta tpr for warm ceiling, cool wall, cool ceiling, warm wall.

I also see to satisfy category B requirements the radiant asymmetry is supposed to be less than 5.

Does this mean that each variable mentioned above (warm ceiling etc) has to be below 5 or is it some form of average.

Any help would be much appreciated.

Thanks in advance

[PCully]

Hi,

I am not familiar with this criteria you are assessing, is there some BRE support desk you can use for BREEAM queries perhaps?

re the set points, yes as long as you are confident the setpoints can be met then certainly if you simulate it you will prove you fulfill the thermal comfort criteria but the sim loses it's value since we know for certain a room served by an apache system with heating and air con will meet whatever conditions you tell it.

Phil

[wyliecoyote]

Hi Phil,

Thanks for the reply.

The criteria im assessing is set out in IS0 7730:2005 for BREEAM Hea 03.

To conform to ISO 7730:2005, we must meet the category B requirements.

Under category B we have the following criteria:

1. PPD
2. PMV
3. DR (Draught)
4. Vertical Air Temp Difference
5. PD caused by warm or cool floor
6. Radiant asymmentry

If anyone else on the forum would know a tiny bit about the radiant asymmetry part that would be great.

Other than that, thank you Phil for your input.

Much appreciated