EPC Convention 6.06 DHW serves multiple buildings
Posted by Andrew Bairstow on 29-Mar-19 10:18 AM
The advice in the article is for meeting the following extract of convention 6.06. There is separate advice for SBEM and DSM

Where the DHW serves multiple buildings, the losses should be apportioned between those buildings based on floor area.If the losses are not known so volume and insulation details are being used the volume cannot be apportioned between the buildings. The assessor should initially run the SBEM calculation allocating all of the storage to the building being assessed and look up the Calculated SBEM value for Storage losses. This figure should then be apportioned between the buildings based on floor area and entered as the Storage losses MJ/month.

DesignBuilder SBEM
This data is not currently (v5.4) available in DesignBuilder but can be found within the output file model_sim.hws within the current SBEM folder (54b for SBEM v5.4.b).

The following instructions explain what must be set in order for SBEM to derive an estimate of total storage losses

1. Create the HWS in the model

2. Storage loss is dependent on the area served thus you will need to assign the system to all the zones it serves before running the calculation.

3. The SBEM folder can be found through the menu:

4. Select to display file name extensions: this will then display the 3 character file type.

5. Copy this file to the relevant project folder

6. Copy/rename the file-type to csv: this will enable your spreadsheet software to identify the format of the file (comma separated variable)

7. The file should open automatically in your default spreadsheet application, displaying the MJ/month for each HWS under that data header

8. Use your site notes to identify the area served by the HWS in the assessed building and the site area served by the HWS. Multiply the reported MJ/month by that ratio.
9. Change the HWS specification to Specify Loss and enter the value (For example, if the ratio was 0.5 then the storage losses would be 464*0.5=232

DesignBuilder DSM

DesignBuilder DSM uses broadly the same calculation to derive storage losses however this data is not available in any output file. There are two options to generate this data:
1. Switch over the analysis type to SBEM in Model Options and then follow the procedure above

2. Use the attached spreadsheet:
   a. Download the spreadsheet attached to this article. Copy to your project folder. Input:
        i. Total Floor Area served
        ii. Assessed Floor Area served
        iii. Cylinder Volume
        iv. Insulation type (single letter)
        v. Insulation Thickness

   b. Enter MJ/month (assessment) into the HWS dialogue:

 StorageLossCalculator.xlsx (10.69 KB)