Re: [EnergyPlus_Support] Sensible cooling rate

In my model each zone is surrounded by interior walls . Thus, each core zone's interior wall is adjacent to its relative perimeter zone's interior wall. These interior walls are defined as below

! Interior Walls

Construction,

int-walls, !- Name

1/2IN Gypsum, !- Outside Layer

1/2IN Gypsum; !- Layer 2

I am guessing that these interior walls do not transfer heat from one zone to another, how can I check if zone's are interacting with each other, i.e. which output variable can be used?

An observation from the html report the cooling systems parameters like calculated design air flow, VAV fan data, etc. changes, when the temperatures are changed. This should not be since the sizing of HVAC should be based on designed day data not the simulated day?

On Friday, March 6, 2015 5:55 AM, "Jean Marais jeannieboef@xxxxxxxxx [EnergyPlus_Support]" <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:

For an insulated space, if outdoors is warmer than indoors the heat can't come in easily...but if you raise the cooling setpoint temperature and then the indoors is warmer than the outdoors, the heat can't get out easily. The bottom core zone may be the "most insulated". At the raised setpoint temperature, it may be that the other zones can get rid of their heat more easily.

2015-03-06 1:01 GMT+01:00 Fakeha Sehar fakeha_s@xxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@xxxxxxxxxxxxxxx>:

Operative temperatures for perimeter zones on top and mid floors are higher as compared to bottom floor's perimeter zones. So mid and top floor's perimeter zones can transfer more heat to their respective core zones. Than why mid and top floor's core zones are cooler as compared to bottom floor core zone ?
I am not sure if in EnergyPlus heat transfer between zones is taken into account, is it? Doesn't look like from my results.

On Thursday, March 5, 2015 2:34 PM, "'jeannieboef@xxxxxxxxx' jeannieboef@xxxxxxxxx [EnergyPlus_Support]" <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:

The zone setpoint temps are AIR temps. The mean radiative temps will be different for the roof, middle and ground adjacent zones, ergo the operative temps will also differ, ergo the PMVs will differ. As this is summer cooling, I would guess the roof zone will have the highest OT and PMV, whilst the ground adjacent will be the most stable.

Mit freundlichen GrÃ¼Ã?en- Sent from my iPhone (excuse the brevity)

i. A.
Jean Marais
b.i.g. bechtold
Tel. +49 30 6706662-23

On 05.03.2015, at 20:04, "Fakeha Sehar fakeha_s@xxxxxxxxx [EnergyPlus_Support]" <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:

Yo are right, the ground floor has slab on grade and top floor has a roof. The top floor core zone receives some heat energy from roof too so it should be more warmer than bottom floor especially at higher set points.

I notice that in the html report, the plug load intensity for the core bottom zone is shown as sum of all the 4 perimeter zones. This error is just in reporting or for calculating core zone load E+ considers sum of perimeter zone loads?

On Thursday, March 5, 2015 1:13 PM, "dru.crawley@xxxxxxxxxxx [EnergyPlus_Support]" <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:

There are differences ? the bottom floor may have a slab on the ground or connected to another space? The top floor has a roof.

From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx]
Sent: Thursday, March 05, 2015 1:12 PM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: Re: [EnergyPlus_Support] Sensible cooling rate [1 Attachment]

The three floors each have their own separate cooling systems. The design conditions for the three cooling systems are same . The three floors are identical. There is no window ventilation.

The above figures are when cooling set point is 27C and lower ones for 24C.I am unable to understand by raising temp. to 27C bottom core zone starts behaving differently. Its operating temperatures, PMV go high when all zones cooling set point temperatures have been raised and cooling systems are indentical.

On Wednesday, March 4, 2015 4:10 PM, "'jeannieboef@xxxxxxxxx' jeannieboef@xxxxxxxxx [EnergyPlus_Support]" <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:

If the air temperature were maintained at the cooling setpoint all the time, then the PMV would be the same in all the zones unless for some reason they have differing humidities. Are they served by the same AHU? If it is window ventilated, are the ventilation rates equal? AFN would take the building height and stack effect into account. Differing leakage and window ventilation (height dependant) may result in differing humidities.

PMV is basically a function of operative temperature and humidity. operative temperature is almost the average of the mean radiant and air temps. The difference must lay with these factors.

Mit freundlichen GrÃ¼Ã?en- Sent from my iPhone (excuse the brevity)

i. A.

Jean Marais

b.i.g. bechtold

Tel. +49 30 6706662-23

On 04.03.2015, at 21:27, "Fakeha Sehar fakeha_s@xxxxxxxxx [EnergyPlus_Support]" <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:

I am unable to figure about below

I have three floors, with one core zone and five perimeter zones each. When the core zone cooling set point is 24C, the top floor is slightly more hot (higher PMV index) as it receives more sunlight, than the mid and bottom floors. Similarly, mid floor has higher PMV index than bottom.

Now when I raise the set point to 27C, I notice that mid floor has the lowest PMV index. Bottom floor has much higher PMV index than mid floor. The sensible cooling rate is higher than that of mid floor, why? Bottom floor PMV index should still have been the lowest.