Z E M C H 2 0 1 2 I n t e r n a t i o n a l C o n f e r e n c e
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building which has the same overall floor area, volume and envelope as the actual
dwelling, but adopts default values for glazed areas, U-values and services based on
one of 5 fuel packages.
The non-domestic equivalent NCM is the Simplified Building Energy Model (SBEM_ the
most recent version being v4.1c
Recently the Passivhaus Trust has been established to promote the adoption of the
German PassivHaus Standards and the use of their PHPP software.
Each of these calculation methodologies has been developed in line with EN ISO 13790
Energy Performance of Buildings – Calculation of Energy Use for Space Heating and
Cooling. In this paper we compare these three methodologies to assess the building
energy and emission performance continuing the recent work by other researchers
(Reason and Clarke, 2008; McLeod et al., 2012, etc). We present some comparisons
between SAP and PHPP in terms of a ‘standard’ building and discuss the interplay
between calculation methodologies and standards, the debate surrounding the definition
of zero energy housing and the need for calibration. Finally we hypothesise the role of
Building Information Models (BIM) software in providing a frame work to close the loop.
Background
Standard Assessment Procedure (SAP)
The origins of SAP lie in the Building Research Establishment Domestic Energy Model
(BREDEM) which was based on energy monitoring undertaken from the mid 1970’s to
the mid 1980’s (Reason & Clarke 2008). BREDEM evolved through several versions
eventually being codified as SAP 2005, which was based on BREDEM-9 and
subsequently evolved into SAP 2009 this evolution saw a move from a single to two
heating zones and from a simple heating season to monthly calculations, as well as
addressing some of the criticism of the Reason and Clarke report.
The current version, SAP2009, like before is a spread sheet based calculation, together
with annexes, the detail of which varies with jurisdiction and use but all of which follow a
similar logic. The outputs of these calculations comprise:
•
Energy Efficiency and Environmental Impact Ratings of the dwelling as
designed and which are used to produce an Energy Performance Certificate
(EPC) which is a regulatory requirement introduced by the Energy Performance
of Buildings Directive (EPBD) as translated in to local UK legislation. In the case
of Scotland is the Energy Performance of Buildings (Scotland) Regulations
2008,
•
Dwelling CO
2
Emissions Rate (DER) and Target CO
2
Emissions Rate (TER) for
compliance with local building codes, in the case of Scotland Clause 6.1.1 of
the Scottish Building Standards Technical Handbook Oct 2011,
•
Fabric Energy Efficiency (FEE) which is an overall measure of the building
fabric efficiency which includes both heating and cooling loads.
There are a number of competing approved software programs available
which
also
include a summertime overheating calculation and a Regulations Compliance Report.
The EE and EI Ratings calculations comprise 13 steps, the first 12 of which are used
(with various defaults) for the DER and TER and the first 8 (again with a set of defaults)
for the FEE. Figure 1 is a process diagram which covers the steps in SAP and highlights
some of the interconnections between the steps.
