[Bldg-sim] Reg: Query For DesignBuilder

[David Cocking]

Hi Kiran,

There isn’t a lot of information here to base a “diagnosis” on, but I suspect your variation in results is linked to changes in the internal floor area. DesignBuilder uses geometry convention templates which give the modeller the flexibility to either fix the geometric construction thickness or vary it according to the construction type/material layers you specify. With some of the geometry convention templates, when you increase the insulation thickness (presumably that is how you improved the U value) and define the building geometry according to the building’s exterior dimensions, then the increased construction thickness will reduce the available floor area/zone volume. Gains such as lighting and equipment are often specified on a per area basis, so a thicker wall (for example) with less zone floor area will reduce the internal gains. This is consistent with the behaviour you have observed.

Please check the Program Help information on geometry convention templates and make sure you understand them and how the template in your model is working. If this isn’t the reason for change you observed, please raise a support ticket through DesignBuilder’s customer support desk.

Kind regards,

David Cocking MSc CEng MCIBSE MASHRAE
Director I Tel: +44 (0)1453 755500 I david.cocking at designbuilder.co.uk<mailto:david.cocking at designbuilder.co.uk>

DesignBuilder Software Ltd, 1st Floor, Clarendon Court, 54-56 London Rd, Stroud, GL5 2AD
www.designbuilder.co.uk<http://www.designbuilder.co.uk/>

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From: Kiran Ghosh [mailto:kirankghosh31 at gmail.com]
Sent: 05 September 2018 13:57
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] Reg: Query For DesignBuilder

Hi,

I am currently modelling a simple HVAC model on DesignBuilder. I need to run the simulation to obtain annual electricity consumption due to Cooling, Lighting and Interior Equipment for different construction materials. For some reason, while all the input is the same apart from the U value for the external wall, the electricity end-use for lighting and interior equipment changes as follows:

U value

Lighting

Equipment

2.04

496.38

885.89

2

494.72

880.84

1.85

487.9

860.3


The LPD and Equipment Power Density remains the same with the same schedule, why is the annual electricity consumption changing?
--
Thanks and Regards
Kiran K Ghosh
+919582904515
+918152036434
kirankghosh31 at gmail.com<mailto:kirankghosh31 at gmail.com>
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