PartL2(2010)ApacheSim

 

Part L (2010) ApacheSim is a facility within the Virtual Environment’s <VE> Compliance view providing facilities for testing compliance with Part L2 of the Building Regulations (2010 edition). A further route to compliance is offered with the VE-SBEM facility; refer to the Part L2 (2010) VE-SBEMSection of this Help Site for further detail.

Part L2 (2010) ApacheSim applies to new buildings other than dwellings in England, Wales and Northern Ireland for which construction did not start before 6^th April 2010. The regulation also covers dwellings with a floor area of more than 450m².

Part L (2002) applies to buildings in England, Wales and Northern Ireland for which construction started before 6^th April 2010. If construction had not started before that date, the 2010 edition of Part L applies.

Data for the Part L (2010) ApacheSim analysis is taken from the <Virtual Environment> model, supplemented where necessary by inputs specific to the requirements of Part L (2010).

Results of the Part L (2010) ApacheSim analysis are presented in three levels of detail:

Pass/fail verdicts for the methods tested.

A summary of the checks carried out within each method and their results (an HTML file).

A report setting out the analysis in detail (an HTML file).

Certain analysis results are processed and displayed immediately data is entered, providing instant feedback to the user.

 

The requirements of The Building Regulations, Part L2 (2010 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 2010 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 2010 regulations have no counterpart of the L2 (2002) Elemental or Whole-building methods.

Within the single compliance route for L2 (2010) 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 (2010) ApacheSim software falls into the second category.

The requirements tested by the software are Criteria 1 to 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.

Both buildings are simulated over a typical year using 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 (2010) compliance calculations means that simulation results as calculated for L2 (2010) 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 2010 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 simulations.

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

This criterion is aimed at controlling summertime temperatures in non air-conditioned rooms. The key provisions are set out in L2A paragraph 64:

Reasonable provision would be to show for every occupied space which is not air conditioned that:

a.   when the building is subject to the solar irradiances for July as given in the table of design irradiances in CIBSE Design Guide A, the combined solar and internal casual gains (people, lighting and equipment) per unit floor area averaged over the period 0630 to 1630 Solar Time (GMT) is not greater than 35 W/m². TM47 gives guidance and supporting data to enable this check to be made and includes an adjustment factor to allow the basic limiting gain of 35 W/m² to be adjusted, dependent  upon the location of the building; or

b.   the operative temperature (the temperature index for thermal comfort as used in CIBSE Guide A) in the conditioned space does not exceed a threshold for more than a reasonable number of occupied hours per year when the building is tested against the CIBSE Design Summer Year appropriate to the building location; or

c.    for school buildings, Building Bulletin 101 specifies overheating criteria and provides guidance on methods to demonstrate that reasonable provision has been made to control excessive solar gains.

The software provides an automated test by method b. Automated tests against the other two criteria will be introduced in due course. In the interim, these criteria may be tested for by suitable application of features available in the <Virtual Environment>.

 

L2 (2010) ApacheSim constitutes one of the Regulatory Frameworks covered by the <VE> Compliance view of the <Virtual Environment>. A brief summary of its features follows.

The <VE> Compliance view covers the following Regulatory Frameworks, which may be selected using the Regulatory Framework selector on the <VE> Compliance toolbar:

UK Dwellings

Part L1 (SAP 9.80) – England/Wales

Part L2 (2010) – ApacheSim method

Section 6 (2010) – Scotland

 

These 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 User Guide.

For the L2 (2010) ApacheSim Regulatory Framework 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.

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 (2010) certain attributes assigned to the ‘real’ building are overridden by attributes representing the standard internal conditions stipulated for L2 (2010) 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.

By selecting ‘Notional’ on the Current model selector, you can view the notional building and interrogate its features. However, no editing is permitted. The notional building is created automatically from the actual building and cannot be modified.

Trial simulations may be performed on the notional building using the button ‘CO₂ emissions: test run (notional building)’.

This dialogue, which appears on a tab at the bottom of the <VE> Compliance screen, deals with Part L2 (2010) ApacheSim data at the building or system level required by the BRUKL compliance module, together with simulation settings for the compliance analysis. It also provides buttons for performing compliance simulations, test runs and simulations related to Criterion 3. Settings on this tab include the building type for Part L2 and a facility labelled ‘Set Building & System Data’, which can be also be accessed via the Apache view Settings menu.

Data relating to individual rooms is entered via the Space Data tabs for the actual building. General Building Regulations data, such as the room ‘activity’, is specified on the Building Regulations tab. Other tabs specify data for heating, cooling, gains and ventilation, some of which is forced to standard settings for the purposes of Part L2 (2010).

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:

Part L (2002) – England/Wales/NI - Analysis: facilities for specifying the Part L analysis to be performed

Results: facilities for viewing the results of the analysis

This dialogue also provides a route to the Part L2 (2010) ApacheSim building and system data.