Apache DSM for Part L2 (2013) not picking up shading

[wyliecoyote]

Hi,

Ive created a model with extensive solar shading and applied all the relevant settings to perform an apache sim EPC.

Ive then made a copy of the exact same project and deleted the solar shading from it leaving me with two separate models, one with shading and one without.

Ive checked the suncast link box within the "set building data" tab in ve-compliance.

Ive run separate suncast simulations aswel.

The model is a 4 storey office block which might as well be a glass box and it has full height glazing on every façade.

The shading is also set as "local shade".

The results for the building with shading are as follows:

Part L TER : 22.1
Actual BER : 22.6
Rating: B 43

The results for the building without shading are as follows:

Part L TER : 22.1
Actual BER : 22.6
Rating: B 44

Maybe im missing something?

Can anyone shed some light??

Regards

[Complex Potential]

Have you checked the actual building solar gains in both results files? Are they identical?

[btysoe]

Could you give a short description of the building and its services?

I would expect a larger difference and can't see a fault in your statements above. presumably you have double checked everything and reran the simulations.

is there a difference in the heating/cooling demand between the two simulations?

Just wondering if something else is dominating carbon emissions. e.g. lighting

doesn't seem correct though

[wyliecoyote]

Thanks for the replies.

Yes, ive checked and re ran simulations a number of times.

So i have checked the result files in vista there.

I see there are three results files with the same name which im assuming are the real, actual and notional buildings.

Ive selected all of the office spaces in both models and im comparing solar gain in both models.

Ive then selected synopsis (min/mean/max) to view the results.

Since all the results files within vista are named the same i have simply selected the different simulation results file while having the synopsis open so i can compare the results.

the first two result files had the exact same values for solar gains.

the final one (which i assume is the actual building, correct me if im wrong) and this is where i see differences in solar gains (20kw, ive summed up the max values in excel)

Model setup is as follows:

Walls: 0.16w/m2.k
Roof : 0.14w/m2.k
Ground : 0.12w/m2.k
Windows :1.4w/m2.k 70%VLT 0.39 G-value

Systems:
FCU: 92% boiler eff, 4.05 eer, nominal eer at default, SFP @ 1.9 with FCU SFP @ 0.5 combined with the best ductwork and AHU leakage
Rads: 92% Boiler efficeny nat gas

Fan coil units applied to office spaces with radiators for circulation areas and toilets with extract fan at 10ach/hr with 0.3SFP.

Office spaces takes up around 80% of the building.

lighting:
Offices: 500lux
Toilets: 200lux
Circluation:200lux
Retail: 300lux

And using 1.7w/m2 per 100lux with this

Its predominatly office space.

Ive included voids. For the voids ive specified ceiling tile (box ticked within construction to retain in notional building and set to internal void and set to associated space) and then slab for the "floor".

Weather file is Belfast

Air permeability at 3.

Any thoughts????

thanks in advance

[btysoe]

a_simulation is the actual building
n_simulation is the notional building (sets the target emission rate)
r_simulation is the reference building (used as part of the EPC)

you should be comparing the solar gains in the "a_simulation (with shading)" result file to the solar gains in "a_simulation2(without shading)" result file.

rather than selecting all rooms i would select a single room where you expect it to benefit from the shading.

a stupid question perhaps... but after deleting the shading and rerunning the suncast have you have ran the the part L calc again?

[Complex Potential]

btysoe beat me to it

The "r_" results file refers to the reference building, not the real building and it's not important for answering your question.

It's only the "a_" results file that you need to be interested in (the actual building) and you need to create a results file with a different name for the run without the shading so that you can compare the solar gains on the two actual building results files side by side.

This is really the only way to tell if the additional shading is having any effect.

From what you have said, I'm not sure if you have done this yet.

CP

[wyliecoyote]

Hi,

So ive checked one room which would benefit from the shading looking at the "a" results file and the results are as follows for "cooling plant sensible load"

Shading : 49kw
No Shading: 39kw

So in actual fact the shading is taken into account but the EPC remains more less the same.

Ive ran the part l and the results are as follows:

Shading: 52.9 kg c02
No Shading: 53.3 kg C02

Anywhere else i could look?

[Terence]

Have you looked at the Heating & Cooling end uses in the results?

I have seen many projects over the years where the user added shading to reduce solar gain and this in turn reduced the cooling demand. The reduced solar also had a side affect though of an increase in heating demand... i.e The result clearly did change when looking at the end uses, it was just a coincidence that the user ended up with the exact same BER (or asset rating).

[Complex Potential]

Hi,

So ive checked one room which would benefit from the shading looking at the "a" results file and the results are as follows for "cooling plant sensible load"

Shading : 49kw
No Shading: 39kw

I'm assuming you have those cooling figures the wrong way round...?

Sounds like it is working as intended but, as Terence says, the addition of shading can increase your annual heating demand as well as reducing cooling and so the net result may not change much.

[wyliecoyote]

So i looked at results again as suggested above.

Boiler loads as follows:

No Shading: 1272kw
Shading: 1276kw

Chiller loads

No Shading: 381kw
Shading: 330kw

And yes those results above were the wrong way around