ASHRAE 90.2 Modelling for Estidama (Abu Dhabi)

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I am carrying out modelling in support of an Estidama (PVRS v1.0)
assessment for a residential development in Abu Dhabi.

Estidama uses the use the Energy cost method in section 8 of ASHRAE
90.2. However, 90.2 requires the use of HVAC efficiencies in accordance
with federal law. There is currently no federal law regarding
efficiencies of HVAC in Abu Dhabi, although there is the Abu Dhabi
International Building code, which I believe is not yet mandatory but
does include minimum efficiencies.

My questions are:

* What heating and cooling systems should be used in the baseline
(prescriptive) building?
* What ventilation system/ fan powers should be used in the
baseline (prescriptive) building?
* What should the COPs/ EERs/ efficiencies be for these systems?

Thanks,

Claire

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Claire

You are right, Estidama is still in a stage of infancy. When I work on
an Estidama project I develop a baseline by identifying the climate to
an ASHRAE climate zone based on the number of heating and cooling
degree days. You can then make the case for ASHRAE climate zone 1
efficiencies as the code compliance standard and governing minimum
performance.

Arpan Bakshi, LEED AP BD+C

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I've only done 90.1 modeling for Estidama PBRS, but I took a look into 90.2
out of interest.

- What heating and cooling systems should be used in the baseline
(prescriptive) building?
- From 90.2-2007 sec. 8.8.4.1., "equipment of the same DOE product
class shall be used in the proposed design and prescriptive..."
- Therefore it depends on your proposed system...
- What ventilation system/ fan powers should be used in the baseline
(prescriptive) building?
- 8.8.4.3., the prescriptive design shall have a similar system
meeting the prescriptive requirements"
- Also depends on system... I might use same fan powers for both or
maybe try the 90.1 sec. G3.1.2.9. fan specs?
- What should the COPs/ EERs/ efficiencies be for these systems?
- From 90.2-2007 sec. 6.9., the equipment performance shall be "in
accordance with federal law or as specified in Table 6.9"
- Therefore if no federal law, use table 6.9

Hopefully someone with more experience can answer the question more directly
or correct me since I haven't submitted any PVRS, and I recommend raising a
CCR to UPC if you still have trouble.

Cheers, and I hope you report your eventual solution!

Marcus Jones, LEED AP, M.Sc.

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Thanks for the replies so far. I am using Tas 9.2.1 software for this
one, but we also have IES available.

Our approach at the moment is to use the same system type in the
prescriptive as in the proposed model but using limiting efficiencies
(etc.) in the prescriptive model. Lighting, equipment and occupancy
gains would be the same in each.

Not many limiting values are actually given in the 90.2 document - it
generally says to use federal law. Table 6.9 only gives values for GSHP
and split systems, which are considered to be 'non-federally covered'.
The nearest thing we have to federal law is the emerging Abu Dhabi
International Building Code, which is found on the Estidama website.
This has a section entitled 'International Energy Conservation Code'
giving specifications for the Standard Reference and Proposed Designs.

I believe it would be acceptable to use this document for values not
explicitly given in the Estidama or 90.2 documents.

Dr Claire Das Bhaumik

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