W h i c h i s t h e B e s t T o o l t o A s s e s s Z e r o E n e r g y H o u s i n g ?
191
made by each of the calculation method. We also explore the algorithms behind these
methods so far as we are able to see these in the relevant literature/technical manuals.
Table 1 charts the inclusions and Table 2 the assumptions where these are apparent.
What cannot be readily compared are the algorithms. In the case of SAP these are
available in the SAP2009 guidance document, which aside from providing guidance for
assessors is also used as the mechanism to confirm the methodology to software
developers seeking approval for calculators, similarly the PHPP algorithms are
embedded in the PHPP spread sheets. In both cases extracting those algorithms is no
simple task and undertaking a comparative analysis requires more than a simple
parametric study (Chlela, et al, 2009).
By contrast the SBEM Technical Manual gives only partial algorithms as SBEM itself is a
“black box” software application provided by the UK government to those who have an
approved interface. Alternatively it can be accessed directly through iSBEM
Table 1: Inclusions
Inclusions
SAP
SBEM
PHPP
Space Heating
Inc
Inc
Inc
Space Cooling
Excluded
Inc (where
present)
Inc (where
present)
Energy Used for Heating Water
Inc
Inc
Inc
Energy for Lighting
Inc
Inc
Inc
Energy for Appliances
Excluded
Excluded
Inc
Energy used for Heating
Incoming Mains Water
Inc in SAP
2009
Excluded
Inc
Impact of Water Evaporation
Inc in SAP
2009
Excluded
Inc
Benefit of Solar Gains
Inc
Inc
Inc
Benefit of Internal Gains
Inc
Inc
Inc
Benefit of Solar HW Systems
Inc
Inc
Inc
Benefit of Natural Lighting
Inc
Inc
Excluded
Benefit of PV, Wind and Hydro
Inc
Inc
Excluded
EN ISO 13790 Energy Performance of Buildings – Calculation of Energy Use for Space
Heating and Cooling sets the overall requirements for any NCM used by an EU Member
State to assess energy performance as required by the EPBD. This standard covers all
types of building unless internal process loads outweigh the energy requirement for
heating and cooling. It allows a variety of approaches in terms of zoning, method and
what energy uses to include or exclude as highlighted in the ASIEPA P164 report.
(Spiekman, 2009).
A building may be considered as a single zone or multiple zones either with or without
thermal coupling. The calculations themselves can be undertaken on the basis of a
quasi-steady-state seasonal or monthly basis, or on the basis of a fully prescribed simple
hourly or detailed hourly dynamic simulation. This flexibility, together with the option to
set temperature set points, occupancy profiles and appliance use etc at a national level
(to reflect national practice), has led to multiple calculation methodologies giving multiple
results (Heath, 2010).
