BEAM Plus Existing Buildings

BEAM P

LUS FOR

XISTING

UILDINGS

PPENDICES

ERSION

1.2

8.1 A

NNUAL

NERGY

A - 3

credit annual energy use benchmark, which will be determined on an

individual building basis taking into account the specific characteristics of

the building, particularly those that will be difficult or impossible to

change even if the landlord is willing to invest in energy efficiency

improvement measures (which is a constraint to existing buildings). This

is intended to make allowance in the assessment outcome for buildings

possessing unfavourable features (e.g. a west facing facade), which are

impractical to rectify, and to encourage landlords to concentrate on areas

where improvements are possible.

The zero-credit benchmark will be determined from the predicted annual

energy use of a Baseline Building model, which would have the same

shape, dimensions, and envelope characteristics, would comprise the

same mix of areas for the same range of types of premises, and would

have the same types of major services systems, including the cooling

medium and the type of system used for condenser heat rejection, as the

Assessed Building.

The Code of Practice for Energy Efficiency of Building Services

Installations (BEC) [

] provides a framework for demonstrating

compliance in which the proposed design has annual energy

consumption no greater than that of a reference case that satisfies the

prescriptive requirements.

The Performance Based Approach described in Section 9 of the Code of

Practice for Energy Efficiency of Building Services Installations is

primarily geared towards demonstrating compliance to performance

requirements in section 5 to 8 of the BEC. A number of important

modifications are listed here for extending the BEC’s Performance Based

Approach for the purpose of quantifying energy reduction as a result of

efficient design.

Energy Reduction Measures Considered for this credit

The major modifications concerns clause 9.5.4.1 in BEC, which states:

In fulfilling clause 9.5.3 (the requirement that the design energy should

not exceed the energy budget), the increase in design energy as a result

of not satisfying the trade-off allowable requirements in clause 9.4.2

(performance requirements for lighting, air-conditioning, lift and

escalators, electrical installations) of BEC, can be off-set with reduction

in design energy as a result of –

(a)

An improvement over the corresponding minimum allowable levels

of performance in any one or more of the items listed with energy

efficiency requirements in Sections 5 to 8 of the Code (lighting, A/C,

vertical transport and electrical),

[This clause effectively limits the

baseline A/C system to be the same as the proposed system with

the same components (albeit with minimum performance

requirements). For example: both baseline and designed building will

have VAV, though the designed building can have better fan

efficiencies]

And/or,

(b) A better OTTV, on condition that the energy reduction (as a result of

better OTTV) counted towards the reduction should be limited to not

more than 5% of the energy budget, and/or

generated on site.

Since the building facade design is considered as difficult to change for

an existing building, the envelope characteristics of the baseline building

model for assessing an existing building will be basically same as the

“as-built” characteristics of the assessed building. Therefore the OTTV is

Electrical and Mechanical Services Department - Code of Practice for Energy Efficiency of Building Services Installation-

Section A3.4 2012