BEAM Plus Existing Buildings

BEAM P

LUS FOR

XISTING

UILDINGS

PPENDICES

ERSION

1.2

8.1 A

NNUAL

NERGY

A - 6

The zero-credit benchmark for the Assessed Building (the existing

building) will equal 150% of the predicted annual energy use of the

Baseline Building. The 50% margin is meant for making allowances for

operating conditions that will inevitably arise which will cause more

energy to be used, e.g. over-time air-conditioning provision for offices in

an office/commercial building and deterioration in performance of the air-

conditioning equipment, etc.

The annual energy use of the assessed building will be determined

based on the records of energy use in the building, as given in available

energy billing and audit data. For a single-user building (e.g. a

government complex), the records will reflect the total energy use in the

entire building. However, for a multi-tenanted building (e.g. a typical

office/commercial building), individual tenants have their consumption

separately metered and it is impossible to ask all tenants to provide their

consumption records for the assessment. The assessment for multi-

tenanted buildings, therefore, will be limited to the consumption of the

landlord. However, where there is air-handling equipment inside tenants’

premises, which are supplied with electricity from the tenants’ meters,

the annual energy use of such air-handling equipment will be estimated

and added to the landlord’s consumption. The zero-credit energy use

benchmark will also take this into account.

Besides the annual energy use, the assessment of the energy

performance of a building includes, where applicable, an assessment of

its peak electricity demand. This will be undertaken in a way similar to

the energy use assessment. The zero-credit benchmark for peak

electricity demand will be 125% of that of the Baseline Building model.

Credits for this assessment will be determined with reference to the

factor of reduction in the peak electricity demand of the Assessed

Building relative to that of the Baseline Building model. Note that this part

of the assessment will apply only to those buildings where electricity

charges are based either on the Bulk Tariff, Large Power Tariff or

Maximum Demand Tariff. Buildings not using one of these tariff will not

be assessed for peak electricity demand under this approach, due to lack

of reliable data.

The characteristics to be incorporated into the Baseline Building model,

including the indoor design conditions, ventilation rates, occupation

density and patterns, internal load intensities and patterns, and

performance of air-conditioning equipment are to be as described in

Section 8.2.

The energy use and peak electricity demand of installations and

equipment other than the air-conditioning installations will be predicted

based on the installed power, the operating hours and the pattern of use

for each type of installations. The assessment will be based on the sum

of the energy use, and the peak electricity demand, of the air-

conditioning and other installations. Here, the assumption is made that

the air-conditioning energy use is the dominant time-varying load whilst

the energy use of other installations is relatively stable and may be

regarded as a steady load.

8.1.3 P

REREQUISITES

A prerequisite for obtaining credits for Annual Energy Use under the

Energy Budget approach is compliance with specific items in the HKSAR

Government’s energy efficiency codes, as follows: