The objective of this webinar was to provide the assessor with the knowledge on how to identify a hot water system and input into iSBEMie correctly. Other items covered included, how to establish the required efficiency data, the assigned storage aspects, individual or bi-valent systems and how to apply it to zones.

1. www.seai.ie

2. Presenter: Brian Collentine
Date: 15th June 2021
Hot Water Systems
Non-Domestic Webinar

3. Overview
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Defaults
Identifying Hot Water Systems
Seasonal Efficiency
Storage System
Secondary Circulation
Bi-valent Systems
Assigning the HWS to Zones
Common Errors

4. Where Hot Water Energy Use Goes
Hot Water
Energy Use
HW Generation
Energy
• Depends on:
• Zone Type
• Zone Area
• Generation
HW Storage
Losses
• Depends on:
• Losses
MJ/month
• Insulation
Details
• Storage
Volume
HW Distribution
Losses
• Depends on:
• Deadlegs if
> 3m.
• HW return
loop length
• HW return
losses/m
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5. Defaults

6. When to assign a Hot Water System
A HWS needs to be selected for:
• Depending on the activity and building type selected
for the zone, a standard hot water demand is
assumed in the NEAP Activity Database. For
example, there is a demand assumed to arise from
the occupants of an office for activities such as
washing hands and washing up cups. This demand
is associated with the office rather than the toilet or
tea room.
 A HWS needs to be assigned to every zone
defined in iSBEMie.
• Any space with a deadleg within it. It needs to be
associated with the appropriate system; through the
zone it serves.
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7. When can defaults be used?
• No evidence of a Hot Water System present, but a hot water
demand is assumed for a zone based on the activity.
• Evidence of a Hot Water System present but cannot be accessed.
• Hot Water Storage system insulation if not accessible.
• Refer to Appendix A4.3 of the NEAP Survey Guide v2 for
guidance on default system entry or when there is no hot water
system present in the building.
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8. HWS Assumed - Default Example no.1
(No Evidence of Hot Water System Present)
Where no evidence of Storage/ Secondary Circulation Losses Present:
• Grid Supplied Electricity should be selected where oil/gas not present.
• No storage system
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9. HWS Assumed - Default Example no.2
(No Evidence of Hot Water System Present)
Where evidence of Storage/ Secondary Circulation Losses Present:
• Where a fuel (oil/gas) is supplied to the building (Age post 1999)
• HWS System Storage/ Secondary Circulation Losses: Based on defaults where
evidence not available.
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10. HWS Assumed - Default Example no.3
(No Evidence of Hot Water System Present)
Where evidence of Storage/ Secondary Circulation Losses Present:
• Where oil/gas is not supplied to the building (Age:- Post 1999)
• HWS System Storage/ Secondary Circulation Losses: Based on defaults where
evidence not available.
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11. Identifying Hot Water Systems

12. Hot Water Systems Types
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13. Dedicated Hot Water Boiler
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A dedicated hot water boiler as defined in SBEM as a
“a heat generator serving a separate hot water storage
unit. It does not provide a space heating service.”

14. Standalone Water Heater
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A standalone water heater as defined
by SBEM as a “unit that combines
hot water storage and a heat
generator in a single unit. It does not
provide a space heating service”.

15. Instantaneous Hot Water Heater
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An instantaneous hot water heater as defined in
SBEM is a water heater with no (or limited)
storage capability.
The water heater instantly heats water as it flows
through the generator and does not retain water
internally.

16. Instantaneous Combi
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An instantaneous combi heater as defined
in SBEM is a space heating boiler that also
provides domestic water heating with no (or
limited) storage capability.

17. Heat Pump (under HWS)
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A heat pump as defined in SBEM is a
heat pump providing only domestic water
heating service.

18. Same as HVAC system
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This option is chosen if the hot water is provided
by an existing HVAC system serving the space
heating load.

19. Documentation Evidence
For Non-default HWS entries:
• Photographs of HWS plant (eg boiler
nameplates and manufacturer name).
• Copies of technical data sheets from
operational and maintenance manuals
(In line with 6.1 of the NEAP Survey
Guide).
• As Built drawings and specifications
for New Final or Existing BERs.
• Design drawings and specifications
for New Provisional BERs.
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20. Seasonal Efficiency

21. Effective Heat Generating Seasonal Efficiency
• Default values should only be used if it is not possible to
obtain the HWS plant efficiency data.
• Non-default efficiencies may be obtained from the
following sources:
 Performance data on “CE marked” literature is
acceptable provided that the literature refers to the
relevant test performance standard.
 Literature from manufacturer referencing the
efficiency and relevant Ecodesign standard.
 Accredited Test certificates to the relevant standard.
 ECA/ ACA websites, where technology has been
tested to the relevant test performance standard.
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Standalone Gas Fired Hot Water Heater:
Efficiency = Output/ Gross input

22. Seasonal Efficiency of Heat Pumps
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• Where a Heat Pump is used for water heating, the assessor must select “Heat Pump” as the generator
type and cannot select “Same as HVAC” irrespective of the presence or not of a heat pump in the
HVAC system.
• Where a heat pump make/model is compliant with the Ecodesign and Energy Labeling Directive or has
EN16147 test data, the “Water Heating Energy Efficiency” is taken directly from the Ecodesign
declaration (%) is converted by multiplying by 2.5 and divided by 100 for entry into iSBEMie.
• For example, a Heat Pump with “Water Heating Energy Efficiency” of 120% is converted and entered
into iSBEMie as follows: 120 x 2.5 / 100 = 3.
• Where there is insufficient documentary evidence available to support the Water Heating Energy
Efficiency a default value must be used. (i.e. 1.5)

23. Storage System

24. Storage System
• The Assessor must ascertain if the HWS system has a storage system.
• The storage volume, insulation type and thickness are entered if the
storage losses in MJ/month are unknown. If no value is entered,
iSBEMie uses default values.
• Where storage volume is not available from other sources, and storage
is accessible, estimate storage volume by measuring the dimensions of
the storage vessel.
• Where storage insulation details are not available from other sources,
and insulation is accessible, estimate insulation depth by measuring its
thickness (e.g. using a pin).
• Default hot water cylinder insulation thicknesses is based on the year of
the unit, as outlined earlier.
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25. Hot Water Storage System Insulation If Not Accessible
• The insulation thickness is based on the age of the storage unit as below:
 Pre 1994: No Insulation
 1994 to 1999: 25mm Factory Insulated
 Post 1999: 35mm Factory Insulated
• If the age of the storage unit is unknown, it must be assumed that the
storage unit is the same age as the building.
• CE marked heaters may be assumed to have at least 25mm of factory
insulation.
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26. Hot Water Storage System Insulation If Accessible
• Where there is access to the hot water storage unit, determine the storage volume by one of the following
ways:
1. Determine the hot water storage volume from a label on the storage unit, provided the label also
references a European or National Standard or is CE marked.
2. Take note of the Manufacturer and Model of the unit and determine the volume from literature from the
manufacturer referencing the relevant standards.
3. Take note of the Manufacturer and Model of the unit and contact the manufacturer regarding the
storage volume. The manufacturer must provide written confirmation of the storage volume.
4. Where data from the above sources is unavailable and the vessel is accessible, measure the volume of
the unit on site. Further detail on this is provided next.
5. Where the hot water storage vessel is inaccessible, documentary evidence from the installer, architect
or engineer identifying the volume of the installed vessel is used.
6. If none of these options are possible base it on the iSBEMie default.
Source: Appendix 9 of the NEAP Survey Guide
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27. Measuring a Hot Water Storage Cylinder
1. Measure the height and diameter of the hot water
storage vessel.
2. For cylindrical vessels that are between 71 and
441 litres, choose the nearest height and diameter
options from the table to determine the volume in
litres.
Insulation thickness is not included in the height or
diameter measurement when using the table.
Source: Appendix 9 of the NEAP Survey Guide
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28. Measuring a Hot Water Storage Cylinder
• Example: The hot water cylinder was measured to
be 500mm in diameter by 1100mm high.
• Use the table in Appendix 9 of the Survey Guide,
and select the nearest height and diameter for
the cylinder.
• In this case it would be ‘500mm x 1200mm’.
• So the volume of the cylinder is 190 litres
Source: Appendix 9 of the NEAP Survey Guide
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29. Measuring a Hot Water Storage Cylinder
• For cylindrical vessels that are outside the range of between 71 and
441 litres, the volume is calculated based on the following:
• V = (pi x r2) x h / 1000
• Where: r = radius of the unit (cm)
• h = height of the unit (cm)
• pi = 3.142
• V = volume of unit (litres)
Source: Appendix 9 of the NEAP Survey Guide
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30. Measuring Enclosed Water Heaters
• The water heater volume is calculated by recording the height, width
and depth of the water heater if the heater is cuboid or the above
formula if cylindrical. The cuboid volume is then calculated as
follows:
• V = h x d x w x 1000
• Where: d = depth of unit (m) minus the insulation thickness as
appropriate.
• h = height of unit (m) minus the insulation thickness as appropriate.
• w = width of unit (m) minus the insulation thickness as appropriate
• V = volume of the cylinder (litres)
Source: Appendix 9 of the NEAP Survey Guide
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31. Measuring Enclosed Water Heaters Example
• Example: A water heater was measured on site with a depth of
330mm, a height of 550mm, and a width of 330mm.
• The unit was installed in 2005, therefore the default insulation
thickness is 35mm.
• The volume of the storage unit is:
• V = h x d x w x 1000
• h = 550 – (35 x 2) = 480mm
• d = 330 – (35 x 2) = 260mm
• w = 330 – (35 x 2) = 260mm
• Volume = 0.48 x 0.26 x 0.26 x 1000 = 32 litres
Source: Appendix 9 of the NEAP Survey Guide
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32. Standing Losses
• SBEM requires the storage losses to be identified as MJ/month (mega
joules).
• This may be available from manufacturers, however, manufacturers are
more likely to quote losses as kWh per 24 hour period, or perhaps as a
value in Watts or kW.
• The point to remember is that 1 kWH = 3.6 MJ and that Watts/kW can be
converted into kWh by multiplying the rate by the number of hours.
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kWh per 24 hour period = 86 Watts x 24 hrs
1000
= 2.064 kWh
kWh per 24 hour period = Watts x Time (hours)
1000

33. Standing Losses Example
• A specific example shows a manufacturer quoting cylinder losses of 2.064 kWh for a 24 hour period, i.e. a
heat loss rate of 2.064 kWh / 24 hrs = 0.086 kW or 86 W. Converting this loss into monthly MJ can be done
simply as follows:
 1 kWh = 3.6 MJ
 2.064 kWh = 2.064 x 3.6 MJ = 7.4304 MJ
• So: (MJ/Month)
 MJ/month = (2.064 x 3.6 MJ/day) x 30 days/month
 Therefore: MJ/month = 222.9
• This procedure should be carried out for each individual storage cylinder identified in the assessment.
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34. Multiple HWS Systems Serving A Building
• In cases where a number of HWS systems with storage capacity are present and they
act simultaneously, the storage capacity should be dealt with as follows:
1. Where two or more HWS systems serve specific independent parts of the building,
these systems should be included in SBEM and the associated storage volumes
assigned to each system.
For example, the image on the right shows an extension (blue) which was added to the
original building (red). A new HWS system was installed to serve the extension (blue)
section while the original HWS system was maintained to serve the original building
(red). The two systems are entered into SBEM and assigned to the appropriate zones.
2. Where two or more HWS serve the same zones simultaneously, the HWS system
that is assigned to the zone is the HWS system that accounts for the majority of the
HWS demand in that zone. The storage capacity should account for all the storage
systems.
3. Where a combination of HWS generators serve the same zones but do not work
simultaneously (such as a backup generator), the volume and storage losses
associated with only one of the systems is inputted into iSBEM.
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35. Documentation Evidence
For Non-default HWS Storage entries, the evidence required is met by one of the following:
• Photographs of HWS Cylinder and nameplates and manufacturer name and manufacturer’s data sheet;
• Copies of technical data sheets from operational and maintenance manuals;
• As Built drawings and specifications for New Final or Existing BERs;
• Design drawings and specifications for New Provisional BERs;
• Hot water storage volume measured on site (and evidence of any calculations retained by the Assessor)
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36. Secondary Circulation

37. Secondary Circulation
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38. Secondary Circulation
• The Assessor must ascertain if the HWS system has secondary
circulation.
• If no values are entered, iSBEMie uses default values.
• The Assessor should use default values when the loop cannot be
observable or determined from As Built drawings and if it is not possible
to obtain the HWS plant details and should have evidence to
substantiate this.
• The secondary circulation pipework length refers to all the pipework, i.e.
flow and return.
• The Pump power (kW) can be found on the pump nameplate, or the
manufacturer’s data sheet.
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39. Secondary Circulation Losses Calculation
• The table below gives indicative thickness of insulation for non-domestic hot water services.
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40. Secondary Circulation Losses Calculation
• For entering the data into iSBEMie the assessor must get the average heat loss W/m.
• For example;
Hot Water Secondary Circulation installed with following pipework length and heat loss:
1. 100m pipe; 17.2mm dia = 6.60 W/m
2. 50m pipe; 33.7mm dia = 8.62 W/m
3. 10m pipe; 76.1mm dia =13.09 W/m
• Average = (100 x 6.6)+(50 x 8.62)+(10 x 13.09)
(100 + 50 + 10)
• Average = 7.64 W/m
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41. Documentation Evidence
For Non-default HWS Circulation entries, the evidence required is met by one of the following:
• Photographs of HWS pump(s) and nameplates and manufacturer name and manufacturer’s data sheet;
• Copies of technical data sheets from operational and maintenance manuals;
• As Built drawings and specifications for New Final or Existing BERs;
• Design drawings and specifications for New Provisional BERs;
• Heat Losses from pipework in compliance with relevant standards.
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42. Bi-valent Systems

43. Bi-valent Systems
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• This sub-tab becomes active only if the generator
type in the General sub-tab is not defined as ‘Same
as HVAC’.
• A bi-valent water heating system is a system in
which the heating is supplied by two (or more)
different types of heat sources.
• In addition to the generator type already defined in
the General sub-tab, additional heat generators that
share the total water heating load with the primary
heat generator can be defined in the Bi-valent
Systems sub-tab.

44. Bi-valent Systems Entry
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• For each additional heat generator, the following
parameters need to be input:
1. Generator type of the additional heat generator
2. Fuel type of the additional heat generator
3. Effective heat generating seasonal efficiency of the
additional heat generator, as a ratio.
4. Proportion, in %, of the water heating load that the
additional heat generator provides.
• If unable to determine the load profile of each system,
assume that the split between the systems is equal (for
example between two systems the split is 50:50).

45. Bi-valent Systems Example
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• Example: A dedicated hot water boiler and an
instantaneous water heater both provide hot water to
a zone, and the load carried by each is not known.
1. Define the “Dedicated hot water boiler” system in the
normal way in the General tab.
2. Go to the bi-valent tab and add select
“Instantaneous hot water only” for the heat source.
3. Enter 1.0 for electrical efficiency.
4. Enter 50% for the % Load.

46. Assigning the HWS to Zones

47. Assigning the HWS to a zone?
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• The HWS defined is assigned to the zones it serves
under the ‘Zones’ tab, and the ‘HVAC and HWS
Systems’ sub-tab within the ‘Building Services’
form.
A HWS needs to be selected for:
• All occupied zones - Depending on the activity and
building type selected for the zone, a standard hot
water demand is assumed in the NEAP Activity
Database.
• Any space with a deadleg within it. It needs to be
associated with the appropriate system; through the
zone it serves.

48. Deadleg Length
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• Affects where the deadleg is 3m or above. There is no change when entering deadlegs less than 3m.
• The length of the draw off pipe to the outlet in the space (only used in zones where the water is drawn
off).
• This parameter is used to determine the additional volume of water to be heated because the cold water
in the deadleg has to be drawn off before hot water is obtained.
• The deadleg distance is measured from the edge of the zone or from the storage vessel/ circulation in
the zone to the outlet point.
• Where pipework is not visible in the zone and drawings are unavailable, allow for the deadleg running
from the edge of the zone or from the storage vessel/ circulation in the zone to the outlet point.

49. Common Errors

50. Default Insulation details not entered correctly
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• The insulation thickness should be based on the age of the storage unit.
• If the age of the storage unit is unknown, it must be assumed that the storage unit is the same age as the
building.
• Appendix A4.3 of the NEAP Survey Guide.
• Example: 2004 building; the age of the storage unit is unknown.

51. Electric Storage Water Heaters
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• Undersink electric water heaters are commonly selected as
‘Instantaneous Hot Water Heater’ in error.
• ‘Instantaneous hot water heater’ are defined in SBEM is a
water heater with no (or limited) storage capability.
• A standalone water heater is defined by SBEM as a “unit
that combines hot water storage and a heat generator in a
single unit.
• Therefore, these types of HWS systems should be entered
as a ‘Stand-alone water heater’ with a storage system.

52. The End
Q&A