PartL2(2006)VE-SBEM

 

VE-SBEM is a facility within the Virtual Environment’s <VE> Compliance view providing facilities for either testing compliance with various Building Regulations, or generating energy performance certificates (EPCs) for the same Regulations.

 

An alternative route to compliance is offered with the ApacheSim facility; refer to the Part L2 (2006) ApacheSim Section of this Help site for further detail.

Part L2 (2006) Regulation applies to new buildings other than dwellings in England and Wales for which construction did not start before 6^th April 2006.

Part F Regulation applies to new buildings other than dwellings in Northern Ireland for which construction did not start before 6^th April 2006.

Part L (2002) applies to buildings in England, Wales and Northern Ireland for which construction started before 6^th April 2006. If construction had not started before that date, the 2006 edition of Part L2, or Part F, applies.

VE-SBEM analysis is not available for Part L (2002).

 

Data for the VE-SBEM analysis is taken from the <Virtual Environment> model, supplemented where necessary by inputs specific to the requirements of the selected Regulation. This data is used to produce an input file for the BRE tool SBEM v3.0. The <Virtual Environment> launches the BRE SBEM tool with the input data file and the BRE SBEM tool performs a compliance assessment, or generates an EPC.

Results of the VE-SBEM analysis are presented as follows

1. Compliance document (PDF file) plus Calculation Summary (one page of graphs as a PDF file) and Calculation Details (more detailed breakdown as a HTML file)

or

2. Energy Performance Certificate (PDF) and Recommendations Report (PDF).

XML files are also generated for lodgement in official databases.

 

The requirements of The Building Regulations, Part L2 (2006 edition) as applied to new buildings are set out in Approved Document L2A^[1]. This document should be consulted in the course of any submission for Part L2 compliance.

The function and scope of the approved documents is set out in the ‘Use of guidance’ section:

“Approved Documents are intended to provide guidance for some of the more common building situations. However, there may well be alternative ways of achieving compliance with the requirements. Thus there is no obligation to adopt any particular solution contained in an Approved Document if you prefer to meet the relevant requirement in some other way.”

The broad requirements of L2 are set out in the Requirement section of Approved Document L2A^[1] (referred to in this document as ‘L2A’). They cover:

Reasonable provision shall be made for the conservation of fuel and power in buildings by:

a. limiting heat gains and losses through i) thermal elements and other parts of the building fabric and ii) pipes, ducts and vessels used for space heating, space cooling and hot water services.

b. providing and commissioning energy efficient fixed building services with effective controls; and

c. providing the owner sufficient information about the building, the fixed building services and their maintenance requirements so that the building can be operated in such a manner as to use no more fuel and power than is reasonable in the circumstances.

The detailed requirements are outlined in Section 0: General guidance, under the heading Demonstrating Compliance. Five criteria must be satisfied (paragraph numbers refer to L2A):

Criterion 1: the calculated CO₂ emission rate of the building as constructed (the building emission rate, BER) must not be greater than the target rate (the target emission rate, TER) which is determined by following the procedures set out in paragraphs 18 to 23.

Criterion 2: the performance of the building fabric and the heating, hot water and fixed lighting systems should be no worse than the design limits set out in paragraphs 33 to 62…

Criterion 3: Those parts of the building that are not provided with comfort cooling systems have appropriate passive control measures to limit solar gains.

Criterion 4: the performance of the building, as built, is consistent with the prediction made in the BER…

Criterion 5: The necessary provisions for enabling energy efficient operation of the building are put in place…

L2A should be consulted for details of special considerations and exemptions applying to particular classes of buildings.

Some of the requirements of Part L2 cannot be tested in software (Criteria 4 and 5 fall into this category). However, IES aims to provide software covering all requirements that can be so tested.

By contrast to L2 (2002), the 2006 regulations offer only one compliance route. This has some similarity with the Carbon Emissions Calculation Method in the 2002 regulations, though there are important differences. The 2006 regulations have no counterpart of the L2 (2002) Elemental or Whole-building methods.

Within the single compliance route for L2 (2006) a choice is permitted regarding the analysis tool used to calculate the BER and TER. The carbon dioxide emission calculations that form the basis of these performance indicators can be calculated using either

The Simplified Building Energy Model (SBEM) developed by BRE, or

Approved commercial software

The L2 (2006) VE-SBEM software falls into the second category.

 

The requirements tested by the software are Criteria 1 & 2 & 3, which are implemented in the software as follows:

 

The BER and TER values are obtained from the simulated carbon dioxide emissions of two buildings.

The ‘actual building’, which forms the basis of the BER calculation, is the building as designed, but subject to standard operating conditions dictating levels and patterns of occupancy, internal gain and minimum ventilation.

The ‘notional building’, which forms the basis of the TER calculation, is a version of the actual building modified in accordance with rules relating to glazing area, insulation and system efficiency. These rules are related to the standards laid down for the 2002 Elemental Method. The notional building is also subject to the standard operating conditions. The notional building is created within the BRE SBEM tool.

Both buildings have monthly heat balances performed for standard weather data appropriate to the building location. Results are automatically fed into the BRUKL compliance calculator provided by BRE.

The standard operating conditions are functions of the building type and the activities occurring within each room. They are laid down in the National Calculation Methodology (NCM)^[3]. It is important to note that the stipulation of standard operating conditions for L2 (2006) compliance calculations means that results as calculated for L2 (2006) will in general be different from those calculated for the ‘real’ building (for example in Apache View or for the L2 (2002) Carbon Emissions Calculation Method).

To obtain the TER, the CO2 emissions for the notional building are modified by certain factors as set out in the General Guidance section L2A under the heading Regulations. Details are set out in L2A.The purpose of these factors is to tighten the requirement on the actual building so that its performance exceeds that of the notional building. By this means the 2006 regulations impose a measurable degree of improvement over the standards applied in the 2002 regulations.

 

Criterion 2 imposes constraints on U-values and other aspects of building and system performance.

Maximum and mean U-values for different classes of construction must not exceed stated values. The software applies checks for compliance with this requirement before performing the actual and notional building calculations.

Conditions are also laid down in the following areas (see L2A section headed Design limits for building services):

Controls

Energy metering

Heating and hot water service systems

Cooling plant

Air handling plant

Insulation of pipes, ducts and vessels

Lighting

 

Criterion 3 requires all spaces in the building without air-conditioning to have a low risk of overheating (see SBEM Technical Manual for a definition of this). SBEM v3.0 is the first version of SBEM which assesses the building against this criterion.

 

The <VE> Compliance view offers the following Methods, which may be selected using the Method selector on the <VE> Compliance toolbar:

ApacheSim

ApacheSim – EPC

SBEM

SBEM - EPC

This Guide covers the last two methods above, in conjunction with selecting either Part L2 (2006) or Part F from the Regulatory Framework selector on the toolbar.

The Regulatory Frameworks all share core features of the <VE> Compliance view, such as the model workspace, the browsers, the menus and the toolbars. For a description of these please consult the <VE> Compliance View Section of this Help Site.

 

For the ApacheSim Method a selector labelled ‘Current model’ appears at the right-hand side of the <VE> Compliance toolbar. This allows you to switch between displaying the actual building and the notional building. For both SBEM methods this selector disappears, as the notional building is generated internally by the BRE SBEM tool, and is only visible to the user in the form of output files.

In most respects the actual building is the same as the ‘real’ building used in other <VE> views and Regulatory Frameworks.  However, there are differences in the Space Data, where for L2 (2006) certain attributes assigned to the ‘real’ building are overridden by attributes representing the standard internal conditions stipulated for L2 (2006) in the NCM methodology.

The notional building differs from the actual building in the following respects, in accordance with the rules set out in the NCM document:

Glazing (and in some cases door) areas are adjusted.

Standard constructions are applied.

Where there are unheated buffer spaces (including unheated roofs) in the actual building, the notional building treats these as heat loss paths for adjacent heated rooms (following the principles laid down in BS EN ISO 13789:1999^[2]). For these adjacencies standard constructions are applied, replacing the heat loss paths (including the unheated spaces) in the actual building.

Standard Apache Systems are assigned to rooms depending on the type of conditioning assigned to the rooms in the actual building.

The notional building is created automatically from the actual building in the BRE SBEM tool and cannot be modified.

Data relating to individual rooms is entered via the Space Data tabs. General Building Regulations data, such as the room ‘activity’, is specified on the Building Regulations tab. SBEM specific data, including all Lighting data is also entered on this tab.

The internal gain data for the room’s Building type and Activity is read by SBEM from its own copy of the NCM database, so Space Data’s Internal gain and Air exchange tabs are not visible (as they would be for the ApacheSim method).

Building regulations data relating to constructions (for instance, whether a window is classified as display glazing) is entered via fields labelled ‘Building Regulations’ within the construction data dialogues in APcdb.

The Part L analysis and results dialogue on the lower edge of the <VE> Compliance view is divided into two parts:

“<Regulation Framework name>- Analysis”: facilities for specifying the Part L analysis to be performed

“Results”: facilities for viewing the results of the analysis

There is also a button for the VE-SBEM version of Building and System data.