Methodology for establishing emissions performance trajectories
ABSTRACT: The methodology for establishing the top 15% most energy-efficient buildings in acityDocument Updated: Dec 2016

1. Introduction
For a non-residential building, the energy efficiency performance requirement is an emissions targets derived from an“emissions performance trajectory” that starts with the emissions performance of the top 15% most energy-efficient buildings(of its type e.g. offices) in its city and declines to zero carbon emissions in 2050.
For a residential building, the energy efficiency performance requirement is a CBI-approved proxy, derived either throughbenchmarking against the local market emissions performance (i.e. emissions performance trajectory) or through analysis of aparticular rating/label as a proportion of total ratings/labels awarded under a scheme.
As an emissions performance trajectory is simply a linear pathway from the emissions performance of the top 15% mostenergy efficient buildings in a local market to zero carbon emissions in 2050, this document focuses on explaining themethodology for establishing the emissions performance of the top 15%.

2. Methodology to establish the top 15% most energy-efficient buildings
For non-residential buildings, the local market is defined as the city.
For residential buildings, the local market may be extended to a wider area such as country, as long as there is consistency inclimate and grid energy intensity within that wider area.
Step 1: Checking the data
The data used to establish the emissions performance of the top 15% most energy-efficient buildings must satisfy the following
requirements:-It originates from a reliable source.
There must be a sufficient sample of buildings that is representative of the market.
Building emissions performance must reflect emissions for the full fuel cycle (scope 1, 2, and 3).
Building emissions performance must relate to operational performance not modeled performance.
Building emissions performance is expressed on an annual basis in kgCO2 terms.

Data could relate to statistical results from a local market survey (where the top 15% has been determined) or a raw data setof individual building emissions performance. The next few steps are only relevant to the latter where the top 15% still has tobe derived.
Step 2: Prepare raw data fields
The key data fields required for the analysis are:A. Year: This is the reporting year. Emissions performance of all buildings in the data set should be based on the same
reporting year, for the latest year available.
B. Geographic range: This relates to the range of postcodes covered by the data set.
C. Boundary for emissions performance measurement: This specifies the boundary for the measurement of emissions
performance of each building (e.g. whole building or base building). The boundary for the data set must EITHER bealigned with CBI’s boundary* OR adjustments may be made in the case of whole building performance being reported,on the condition that reliable assumptions can be made, and at the end of the process (i.e. Step 5).
D. Emissions performance: Must fulfill the requirements specified in Step 1 (i.e. reflect emissions for the full fuel cycle, relate
to operational performance, expressed on an annual basis in kgCO2 terms).
E. Emissions intensity factor: This is the factor used to convert emissions performance into a level of emissions intensity.
This is more relevant for non-residential buildings than for residential buildings. For non-residential buildings, the factor tocalculate emissions intensity is either floor area (in square metres) or number of rooms, whichever is relevant for theparticular building type (e.g. offices, hotels).* For residential buildings, the lower variation within one building type (e.g. 3bedroom dwellings) means that emissions performance can expressed for the whole building, removing the need tocalculate emissions intensity.
* For each building type, Appendix 1 provides information on:- CBI’s boundary for emissions performance measurement (e.g. whole building or base building)- The factor to calculate emissions intensity (e.g. floor area or number of rooms)- The measurement basis for the emissions intensity factor (e.g. net lettable area as the measurement of floor area forcommercial offices)Step 3: Calculate the emissions intensity of each building in the data set
The emissions intensity of each building in the data set is calculated based on (D ÷ E).
Using the example of commercial offices, the emissions intensity of each office is calculated as:= Annual emissions performance of that office (in kgCO2) ÷ Floor area of that office (net lettable area in m2)= X kgCO2/m2
Step 4: Eliminate extreme outliersThis step involves identifying and eliminating extreme outliers from the data set that may skew the calculation of the emissions
performance of the top 15% most energy-efficient buildings.
The emissions performance of the median (“MD”), first quartile (“Q1”) and third quartile (“Q3”) of the data set arecalculated based on results from step 3.
To establish the performance range for “mild outliers”, a calculation is made to derive the “mild deviation” (“MDV”):(Q3 – Q1) × 1.5
The performance range for “mild outliers” is then (Q1 – MDV) to (Q3 + MDV).
To establish the performance range for “extreme outliers”, a calculation is made to derive the “extreme deviation” (“EDV”):(Q3 – Q1) × 3
The performance range for “extreme outliers” is then (Q1 – EDV) to (Q3 + EDV).
“Extreme outliers” are omitted from the data set for the next step in the process.
Step 5: Calculation of emissions performance of the top 15% most energy-efficient buildings
Buildings in the data set, excluding “extreme outliers”, are arranged from lowest to highest emissions intensity and theemissions intensity of the top 15% of the data set is taken.

Appendix 1
Building Type
Commercial Buildings(Non-Residential)- Offices-Hotels
Shopping centres- Warehouses…
…

Boundary foremissions performancemeasurement

Factor foremissions intensity
calculation

Measurement basis foremissions intensity
factorBase building1

Floor area (square metres)

Net lettable area2

Number of rooms
Floor area (square metres)

May be estimated fromgross floor area*
N.A.
Net lettable area

Floor area (square metres)

May be estimated fromgross floor area*???

Whole building
Base building

Base building

Public buildings(Non-Residential)- Hospitals- Schools- Libraries…
Residential Buildings…
* On the condition that reliable assumptions can be made. An adjustment is made at the end of the process (i.e. Step 5).

1 The base building (i.e. landlord component) of energy consumption typically comprise the energy consumed by landlord-owned plant andequipment that are required to service the building and are not controlled by the building’s tenants. It includes energy end uses related to:heating, ventilation and air conditioning; lifts and escalators; car park lights and ventilation; common area light and power; exterior lighting
and signage. It excludes energy end uses that are controlled by the building’s tenants: lighting within tenant areas; tenant power; tenant
supplementary cooling; tenant data facilities.
2 This is the normal measure of floor space within a commercial building. It is normally the total occupiable floor space of a building takenfrom the inside surfaces of the exterior walls and/or the mid-line of any shared walls and excludes areas such as common stair wells, toilets,
lift lobbies and vertical service ducts.