A conservatory attached to and built as part of a new dwelling

There are three possibilities, one where there is no separation between the conservatory and the dwelling, and the other two where there is separation No separation - the conservatory should be treated as an integral part of the dwelling Separation, unheated - energy savings can be achieved if the conservatory is not heated Separation, heated - if fixed heating installations are proposed, they should have their own separate temperature and on off controls.

Guide to Part L of the Building Regulations

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AD L Section General Guidance

The general guidance for Part L2 is broadly similar to that given for Part L1. However, because of the large range of building types in the non-domestic sector, the guidance is broader in scope, and there are some differences in the detail. Heat losses through walls, roofs, floors, windows and doors, etc. must be kept within acceptable limits by means of suitable levels of thermal insulation. Also, where it is possible and appropriate, any beneficial gains from solar heat and more efficient...

Adjustments allowed by the elemental method

When applying the elemental method to a complete dwelling, the only adjustment available concerns the standard area provision for windows, doors and rooflights. If the U-value of any or all of the windows, doors and rooflights is greater than normal, due say to lower performance glazing, then the area-weighted average U-value may exceed the value given in Table 2.1, and may therefore lead to a failure to meet the requirement. In such a case, the total area may be reduced to compensate. The...

Alternative test methods

Although the air pressurisation test is the only method offered by the Approved Documents, there may be occasions when it is difficult to apply. There a number of alternative test methods which can give a measure of airtightness, though at present none are as reliable. The acoustic method consists of the generation of very low frequency sound waves within the building. These produce a continuously fluctuating pressure difference, whose magnitude depends on the leakage area of the building. The...

Building fabric Continuity of insulation

Continuity of insulation is necessary in order to avoid excessive thermal bridging. The design requirements for achieving this are as described for the elemental method in section 3.3.2.2.1. In addition, the person carrying out the work has a responsibility to ensure that compliance with Part L is achieved. For a new building, that person will normally be The developer who has carried out the work subject to Part L The contractor who has carried out the work subject to Part L The sub-contractor...

Building logbook

The building owner and or occupier must be provided with a log-book. The logbook should contain details of The installed building services plant The installed building services controls The method of operation of the plant and controls Any other matters which collectively enable energy consumption to be monitored and controlled. The log-book information should be provided in summary form and be suitable for use on a day-to-day basis. The log-book may refer to information contained in other...

Buildings constructed from subassemblies

A new building, however it is constructed, must normally comply with all the requirements of Schedule 1. However, with respect to the external fabric of buildings constructed from sub-assemblies, reasonable provisions for the conservation of fuel and power may vary according to the circumstances of the particular case. Examples where this may apply are A building created from the external fabric sub-assemblies of an existing building by dismantling, transporting and re-erecting on the same site...

Buildings other than dwellings tradeoff between construction elements

When applying trade-off, the requirement is that the transmission heat loss from the actual building is less than or equal to the heat loss for a notional building. This requirement may be written as The U-values in the notional building are taken as equal to the values in the elemental table, and so the allowance for thermal bridges is taken as a proportion of these. Thus Ht actual < (1 + a)XAUelemental or Ht actual < 1. 1S AUelemental

Carbon and carbon dioxide indices

In order to be consistent with the general objective of Part L, which is to reduce pollution of the atmosphere (especially by carbon dioxide) caused by energy consumption in buildings, the fuel consumed by a building is most conveniently expressed in terms of the amount of carbon that has been generated. In AD L2, therefore, performance targets are expressed in kilograms of carbon, and not in terms of an energy unit such as gigajoules or megawatt-hours. Occasionally, there may be a preference...

Comparison with other standards

Several countries, especially in Scandinavia and North America, have had standards for airtightness for some time. Comparisons with standards in these and other countries are difficult because of differences in the way those standards are expressed. For example, although the 50 pascal pressure difference is commonly used, other standards may use higher or lower pressures. Also, some standards exclude solid ground floors and use the air leakage index. It has also been common to express the...

Compliance with Part L

There are two ways of demonstrating compliance with the need to limit thermal bridging around openings and junctions. These are By following the recommendations of the 'robust construction details' publication 2 , and by adopting the design details published therein, either exactly or sufficiently closely as to achieve a performance that is just as good, or By demonstrating by calculation that the extra heat loss due to linear thermal bridges is within certain specified limits. The first method...

Correction for air gaps

Where R1 is thermal resistance of layer containing the gaps Rt is total thermal resistance of the whole component AU11 is obtained from Table 5.1. Table 5.1 Correction factors for air gaps. Table 5.1 Correction factors for air gaps. Insulation installed in such a way that no air circulation is possible on the warm side of the insulation. No air gaps penetrating the entire insulation layer. Insulation installed in such a way that no air circulation is possible on the warm side of the insulation....

Cracks or small openings with a typical dimension less than mm

The Reynolds Number is low, and so a laminar flow type of equation may apply. For a plain pipe of radius r and length x, the flow rate Q is given by Ap is pressure difference between the ends of the pipe n is an index whose value in this equation is 1. However, the flow paths are never as simple as a plane pipe, and the flow is rarely perfectly laminar, and so it is usually considered that a more representative version of this equation is of the form where C is a flow coefficient, normally...

Dedicated computer or communications rooms

The general requirement for ACMV is that buildings should be designed and constructed such that The form and fabric of the building do not create a need for excessive installed ACMV capacity. Glazing type, glazing ratios, and solar shading are important in limiting cooling requirements Fans, pumps and refrigeration equipment are reasonably efficient and are not over-sized, so that the capacity for demand and standby is no more than necessary Facilities for the management, control and monitoring...

Detached dwelling

Figures 8.2a and 8.2b are plan views of the ground and first floors of a detached dwelling. The dwelling lies approximately on a north-south axis. The windows have metal frames, with 24.8 m2 on the southern face, 11.4 m2 on the northern face, and 1.8 m2 to the side. It is proposed to fit a mains gas fired boiler with a SEDBUK rating of 76 . The areas and U-values of the elements of the dwelling are given in Table 8.2. The total area of openings is 43.70m2, and the total floor area is 156.00m2....

Determining the thickness of insulation for floors

Ground floors must be considered separately from upper floors. In the case of ground floors, the U-value depends not only on the insulation but also on the size and shape of the floor. Both size and shape are taken into account by means of the ratio P A, where P is the perimeter length in metres of the whole of the ground floor, and A is the total area in square metres of the ground floor. Further, AD L1 does not give any allowable reductions for components in the floor structure, and so the...

Determining the thickness of insulation for roofs

Figure 4.1 illustrates three common roof types, and Table 4.6 gives the base thickness of insulation for these roofs. Because the base thickness may not be the minimum, the reductions in heat flow due to other elements of the construction must be considered, and further corrections may be made to reduce the base thickness to give the minimum thickness. The amounts by which the base thickness may be reduced are given in Table 4.7. (b) Insulation laid between and over joists or rafters (b)...

Determining the thickness of insulation for upper floors

For upper floors, i.e. floors above an external space, Table 4.14 applies, together with the allowable reductions in Table 4.15. Note that in Table 4.14 it is assumed that the proportion by area of structural timber in the timber floor construction is 12 , corresponding to 48 mm wide timber joists at 400 mm centres. The U-value for other proportions of timber must be calculated using the procedures in Chapter 5. Table 4.14 Thickness of insulation for upper floors of timber construction. Thermal...

Determining the thickness of insulation for walls

The procedure is the same as for roofs. Select the desired U-value, decide on the position of the insulation layer and method of fixing, and use Table 4.5 to obtain AU, the correction to the U-value. The design U-value is found from the desired U-value using Table 4.8 Base thickness of insulation for walls. Thermal conductivity of the insulation material, W mK Design 0.020 0.025 0.030 0.035 0.040 0.045 0.050 W m2K Base thickness of insulation layer, mm Thermal conductivity of the insulation...

Dwellings target Uvalue method

The total heat loss coefficient for a dwelling may be written where AT is the total area of all exposed elements, including the ground floor. The criterion is formulated by using the target U-value for the dwelling instead of the elemental U-values of the component parts. Thus we require that HT is within the limit given by Ht < AtUt + aATUT Combining these two equations gives AtUav + ELT < AtUt + aATUT Dividing by AT allows the equation to be written as The left hand side of this equation...

Example Calculation of installed circuit power

A new sports hall consists of a sports area for badminton courts, changing room toilet facilities, an entrance reception area, and an office. The lighting schedule is Sports playing area 8 No. 100 W high pressure sodium downlighters Changing room toilets 12 No. 15 W compact fluorescent lamps Entrance reception area 10 No. ceiling recessed 50 W tungsten halogen downlighters Office 2 No. 85 W 38 mm diameter, 2400 mm long tubular fluorescent. Controls for the playing area, entrance reception area...

Example Calculation of the average lamp efficacy

A new restaurant consists of a reception bar area, a dining area, kitchens and circulation toilet areas. It is desired to use decor lighting appropriate to the building's function, and so, in the bar and dining areas, it is proposed to use a combination of concealed perimeter lighting and local lighting over tables. Controls for the reception and dining areas will be by local switching from behind the bar, and lighting to all other areas will be by local switching. The building is neither an...

Example calculations

The calculation method is most conveniently explained by means of examples. Example 5.1 Cavity wall Figure 5.2 shows a cavity wall consisting of external brickwork, cavity, lightweight blockwork, mineral wool insulation within a timber sub-frame, and internal plasterboard. The blockwork and the mineral wool are the main providers of thermal insulation in this construction, and both suffer from thermal bridging. The blockwork is bridged by the mortar joints, and the mineral wool is bridged by...

Example calculations for floors

Example 4.9 Solid floor in contact with the ground Figure 4.11 shows a solid floor. The maximum U-value allowed by the elemental method, from Tables 2.1 and 3.1, is 0.25 W m2K, and it is desired to find the necessary thickness of insulation of thermal conductivity 0.025 W mK. Table 4.11 must be used, and this requires the perimeter to area ratio to be calculated Floor perimeter 6 + 2 + 4 + 4+10 + 6 32m Floor area (6 x 6) + (4 x 4) 52 m2 Perimeter to area ratio, P A 0.615 0.6 From Table 4.11,...

Example Insulated suspended ground floor

Let the floor in Example 6.4 be insulated, with insulation fitted between the floor joists. The U-value of this floor deck may be calculated in the same way as the U-value of a wall, using the method in Chapter 5. Assuming the result of this calculation is a U-value of 0.45 W m2K, the U-value of the floor is found as follows Rf -1 - 0.17 - 0.17 2.22 - 0.34 1.88 m2K W The uninsulated U-value, from Example 6.4, is Uo 0.69, and so (1 Uo)- 0.2 + Rf 1.45 - 0.2 + 1.88

Example of Tradeoff Calculations

The elemental method for buildings other than dwellings provides some design flexibility by means of trade-offs. There are two possible methods of trading off Trade-off between construction elements by varying U-values and areas Trade-off between heating system efficiency and fabric performance, i.e. the areas and U-values of construction elements. The principle that governs these trade-offs is that the actual building should be no worse than a notional building of the same size and shape which...

Example Solid ground floor over clay subsoil

Figure 6.2 illustrates the floor plan of a detached house. The sub-soil is clay, and the floor is uninsulated. First, calculate the perimeter to area ratio P 2 x (10.2 + 6.7) 33.8 m A 10.2 x 6.7 - 3.5 x 2.7 58.89m2 P A 33.8 58.89 0.57 m m2 The U-value is found from Table 6.1, using the column for zero thermal resistance. The Approved Document recommends that the row nearest to the actual P A value is used in this case the nearest row to 0.57 is P A 0.55. It is not necessary to interpolate...

Example Solid ground floor over clay subsoil with allover insulation

The floor in Fig. 6.2 is now provided with all-over insulation between the screed and the structural floor. The insulation layer is 75 mm thick and has a thermal conductivity of 0.040 W mK. The resistance of the insulation layer is In Table 6.1 we again use the row for P A 0.55, but this time we must interpolate between the columns for Rins 1.5 and Rins 2.0. This interpolation is necessary because the change in U-value between columns is more significant than the change between rows. Thus At...

External lighting

The requirement is in respect of systems fixed to the building, and includes porches but not lighting in garages and car ports. The guidance suggests two alternative solutions (1) Provide controls which automatically extinguish the system when there is enough daylight and when the the system is not required at night, or (2) Install sockets that will only take lamps of luminous efficacy greater than 40 lumens per circuit-watt. As for internal lighting, this means that typically fluorescent tubes...

General definitions applicable to L and L

Both L1 and L2 begin with a reminder that designing to minimise energy consumption may carry the risk of technical problems in other areas. High levels of thermal insulation, and careful attention to draught proofing can cause problems due to Surface condensation in roof spaces Inadequate ventilation for occupants Inadequate ventilation and air supply to combustion systems and flues. Other potential problems are Rain penetration causing, among other things, damage to thermal insulation. This is...

Heating and hot water systems for dwellings

The requirements can be considered under four headings The provision of hot water by means of systems which incorporate hot water storage Insulation of pipes and ducts Commissioning, operating and maintenance instructions. 2.3.7.1 Controls for space heating The guidance given in AD L1 is most suitable for systems in which heat is distributed from a central heat source. For such systems, it is necessary to consider the inclusion of zone controls, timing controls and boiler interlock controls....

Historic buildings

Buildings situated in conservation areas Buildings of architectural and historical interest and which are referred to as a material consideration in a local authority development plan Buildings of architectural and historical interest within national parks, areas of outstanding natural beauty, and world heritage sites. Any work on an historic building must balance the need to improve energy efficiency against the following factors The need to avoid prejudicing the character of the historic...

Infrared radiation

All matter continuously emits and absorbs electro-magnetic radiation. An increase in the surface temperature of a material causes an increase in the intensity of radiation emission, and also alters the wavelength distribution of that radiation. Perfect emitters, that is materials which emit the maximum possible intensity of radiation at all wavelengths, are called 'black body' radiators. All normal materials emit less than a black body, the difference being described by the emissivity of the...

Installation of energy meters

The building engineering services should be provided with sufficient energy meters and sub-meters to enable owners or occupiers to measure their actual energy consumption. Sufficient instructions, including an overall metering strategy, must be provided so that owners or occupiers are able to attribute energy consumed to the end use of that energy, and to be able to compare operating performance to published benchmarks (see item 9 of section 3.5.1.2 above). In order to develop a metering...

Introduction

National Building Regulation Standards for the insulation of buildings were first introduced in 1965, and at that time were applicable only to dwellings. Their objective was part of an overall aim to maintain minimum standards of health and safety within buildings. Since then, the insulation standards have been progressively improved and their scope extended to all buildings. Simultaneously, the objective of this part of the Building Regulations has expanded from a concern for health and safety...

Joints around windows and doors

Because of this, there is a requirement to construct in such a way as to avoid significant thermal bridges. This can be done most easily by adopting robust construction details that have an authoritative recommendation. Although the detailing given in the 'robust construction details' document 2 is intended mainly for dwellings, it is also relevant to other buildings of similar construction and with similar internal environmental conditions. The detailing may not be satisfactory for a building...

Lamp and luminaire efficiency

The efficiency of the lighting system is measured by its luminous efficacy. The basic requirement is that the initial luminous efficacy of the lamp and luminaire, averaged over the whole building, should be not less than 40 luminaire-lumens per circuit-watt. This criterion must be applied to office, industrial and storage buildings, but it can also be applied to any other type of building. Note that Luminaire-lumens means the useful light emitted into the space by the lamp-luminaire combination...

Lighting controls

The aim of lighting controls should be to encourage the maximum use of daylight and to avoid unnecessary use of lighting when spaces are not occupied. This should not, however, create a situation in which the operation of an automatically switched lighting system endangers the passage of building occupants. Guidance on lighting controls is given in BRE IP 2 99 43 . 3.3.2.12.1 Controls in offices and storage buildings The requirement can be met by providing local switches in easily accessible...

Lighting systems

If a complete lighting system serving more than 100 m2 of floor area is to be replaced, then the new system should comply with the requirements for a new building. In the case of partial replacement, then If only the complete luminaries are replaced, provide new luminaries as specified in either section 3.3.2.11.1 or section 3.3.2.11.2, whichever is appropriate (note however that this requirement does not apply when only components such as lamps or louvres are replaced) If only the control...

Linear thermal bridges

Many thermal bridging effects in building structures may be treated as a linear thermal bridge. Examples are lintels (in any material), details around openings, junctions between plane elements (walls roofs and walls floors), or any similar detail that can be specified primarily in terms of its length. The extra heat loss due to the presence of the thermal bridge is accounted for by means of the linear thermal transmittance, which is the heat loss coefficient per unit length of the bridge. The...

Meeting the Part L standard

The relevant legal requirement is that reasonable provision should be made to limit heat loss (or gain) through the fabric of a building. This provision should include the limitation of air leakage. In the case of dwellings and other buildings of less than 1000 m2 floor area, the Approved Documents state that compliance can be demonstrated either by adherence to approved detailing 2 , or by conducting a satisfactory pressurisation test on the finished building. For buildings of greater than...

Methods of Meeting the Lighting I Standards

Paragraphs 1.41 to 1.59 of AD L2 set out the lighting efficiency standards that are required within the elemental method. The standards have two aims To ensure adequate efficiency of the lamps and luminaires in converting electricity to useful light To provide sufficient controls to ensure that the lighting is switched on only when it is required, i.e. when there is insufficient daylight and when the space is occupied. In any lighting design, both of these aims must be kept in mind, but for...

Minimisation of

(1) the length of circulation loops (2) the length and diameter of dead legs. For conventional hot water storage systems, ways of satisfying the requirement would be to (1) Provide controls that shut off heating when the required water temperature is reached (2) Shut off the supply of heat during periods when hot water is not required. Guidance on ways of meeting the requirements include (1) In small buildings, Good Practice Guide GPG 132 41 (2) In larger, more complex buildings, or for...

Minimum specifications for windows

Inspection of the U-values in Tables 4.2 and 4.3 reveals the required design specification for a window to meet the maximum U-values of 2.0 or 2.2 W m2K given in Tables 2.1 and 3.1. For double glazing with a 6 mm air gap in a wood or UPVC frame, it is not possible to keep within the maximum U-value for any of the listed types of glass. With a 12 mm air gap there are three possibilities, and with a 16 mm air gap there are six. For double glazing in metal frames there is only one possibility, and...

Offices

O Daylit - window area 30 of office external wall area, glazed with clear low-E double glazing units furthest luminaire less than 6 m from window o Controls - local infrared switches Entrance foyer, corridors and toilets o Usage - as for office o Non-daylit - electric lighting only o Controls - automatic on and off by occupancy sensing. Comparing the specification for the lighting controls with the requirements of paragraphs 1.56 and 1.58 shows that they meet the requirements. Note, however,...

Or complete luminaires

That will only take lamps of luminous efficacy greater than 40 lumens per circuit-watt. The minimum number of locations must include those that are expected to have most use, and can be calculated from the number of rooms in the dwelling by the formula the result being rounded up to the nearest whole number. Thus, for three rooms the minimum number of locations is one, whereas for four rooms the calculation gives 13, which is rounded up to two. When counting the rooms in the house, note that...

Parameters and equations

Qslw the solar load from windows, per unit of the zone floor area (W m2) Qslr the solar load from rooflights, per unit of the zone floor area (W m2) It is necessary to define Qslw and Qslr separately because they require different equations for their evaluation. Ag the area of glazed opening in the window wall(s) of a perimeter zone (m2) Ar the total area of rooflight(s) in a perimeter or interior zone (m2) qsw the solar load due to a window, selected from Table 13.1 (W m2 of glazing) qsr the...

Plant management features for FD Table

The plant management features in Table 12.1 should be interpreted as follows. Operation in mixed mode with natural ventilation If there are sufficient openable windows to provide the required internal environment by means of natural ventilation when external conditions permit, then this will only qualify as mixed mode operation if the perimeter zone exceeds 80 of the treated floor area. In addition, systems with cooling or refrigeration must have interlock controls to inhibit the air...

Plant management features for FR Table

This applies to systems that, when conditions allow, permit cooling to be obtained without the operation of the refrigeration equipment. Examples are the 'strainer cycle' and the 'thermosyphon'. Variation of fresh air using economy cycle or mixed mode operation This refers to systems that incorporate an economy cycle in which the mix of fresh and recirculated air is controlled by dampers, or to mixed mode operation as defined for Table 12.1. Controls to restrict hours of operation This applies...

Poorest acceptable Uvalues

The flexibility built in to the target U-value and the carbon index methods allows the U values of some parts of the roof, walls or floor of a dwelling to be worse (i.e. higher) than the values given in Table 2.1, provided that this poorer performance is compensated for elsewhere. However, if the U-value of any part of a roof, wall or floor is too high, there is an increased risk of both surface and interstitial condensation. Consequently, regardless of the results of the target U-value or...

Relationship between SAP and CI

The connection between SAP and CI is not consistent because one depends on fuel prices whereas the other depends on C02 emissions. Fuel prices are affected by market forces and taxation policy, while emissions are a fundamental property of the fuel. Nevertheless there is an approximate correspondence, and the examples in AD L1 Appendix F illustrate this. The results of these examples are given in Table 9.1, in which sn is the SEDBUK rating of the boiler. It may be noted that in all those...

Residential and conference centre

A new building is planned as a residential and conference centre. The building will be three-storey, but part of the ground floor will be two-storey in height with vehicle unloading bay doors. The building will be heated by two identical natural gas fired boilers of efficiency 78 and of combined rated heat output of 120 kW. The main characteristics of the building are Dimensions rectangular, 40 m x 15 m on plan, 10.5 m high, flat roof Windows fitted with 12 mm air gap low-E (sn 0.05) argon...

Roofs walls and floors

The tables in AD L1 and AD L2 do not give U-values for complete constructions. Rather, they enable the calculation of the minimum thickness of the insulation layer that is necessary to achieve a desired U-value. However, the minimum thickness is applicable only when the insulation layer is perfectly continuous. In practice, U-values may vary because of Mechanical fasteners penetrating the insulation layer Precipitation on inverted roofs. The effect of each of these factors is to add a...

Semidetached dwelling

Figure 8.1 is a plan view of the ground floor and first floor of a semi-detached dwelling. The dwelling lies approximately on a north-south axis. The windows have wood frames, with 11.8m2 on the southern face, 9.2m2 on the northern face, and 1.2 m2 to the side. It is proposed to fit a mains gas fired boiler with a SEDBUK rating of 81 . The areas and U-values of the elements of the dwelling are given in Table 8.1. The total area of openings is 26.00 m2 and the total floor area is 94.08 m2. The...

Solid floor in contact with the ground

Fig. 4.8 Solid floor in contact with the ground. Fig. 4.8 Solid floor in contact with the ground. Table 4.11 Thickness of insulation for solid floors in contact with the ground. Thermal conductivity of the insulation material, W mK Design P A - U-value ratio 0.020 0.025 0.030 0.035 0.040 0.045 0.050 W m2K m m2 Base (minimum) thickness of insulation layer, mm W m2K m m2 Base (minimum) thickness of insulation layer, mm 4.2.3.2 Suspended timber ground floor Fig. 4.9 Suspended timber ground floor....

Solid ground floors with edge insulation

It is often more practical to insulate a floor by means of edge insulation. The edge insulation may be laid horizontally or vertically, as shown in Fig. 6.1. Where horizontal or vertical edge insulation is used instead of all-over insulation, a correction factor is subtracted from the U-value for an uninsulated solid ground floor. The correction factor is a combination of the perimeter to area ratio and an edge insulation factor, *. Thus where U0 is the value for an uninsulated floor taken from...

Space heating

Space cooling, including chilled water and refrigerant pipework Hot water supply for normal occupancy. The Building Regulations do not apply to pipework, ductwork and vessels for process use. The standards given in BS 5422 29 are suitable for determining the amount of insulation to be applied to pipework, ductwork and storage vessels. In the case of storage vessels, the recommendations in BS 5422 29 for flat surfaces should be used. When, as a result of fluid flowing or being stored, the heat...

Special cases Exemptions

There are two types of exemption from the requirements of L2 when there are low levels of heating and or when there are low levels of use. 3.2.2.1.1 Low levels of heating A building with a heat requirement which does not exceed 25W m2 may be regarded as having a low heat requirement, and therefore does not require measures to limit heat loss through the fabric. In such a case, the fabric insulation is likely to be chosen for operational reasons. Typical examples are A warehouse where general...

Specific guidance

For specific guidance, Approved Document L1 offers three methods for demonstrating that reasonable provision has been made for limiting heat loss through the building fabric. The elemental method has the advantages that it involves a minimum of calculation effort, and is appropriate for alterations and extensions as well as for new construction. However, it allows less flexibility in the design of the dwelling than other methods and can only be used with certain heating systems Fig. 2.1a...

The carbon index method for dwellings

There are two indices used for measuring the amount of carbon dioxide put into the atmosphere by a dwelling. The carbon factor (CF) is the carbon dioxide emission in kilograms per year per m2 of floor area. As this measures the actual quantity of carbon emitted, it follows that decreasing its value is good. The carbon index (CI) is calculated from the carbon factor, converting it from a linear to a logarithmic scale and also inverting it. The conversion formula was chosen to provide a more...

The carbon intensity of heating plant

The requirement is that heating plant should be reasonably efficient. The method of demonstrating compliance is to show that the amount of carbon generated by the heating plant is within specified limits at both maximum output and part load. The method applies to Heating plant serving hot water and steam heating systems Heat pumps (irrespective of the form of heat distribution). The carbon intensity of the heat generating equipment must be calculated at maximum heat output of the heating...

The carbon performance rating and the wholebuilding method CPRhlac

The whole-building CPR takes account of heating, lighting and air conditioning. In principle it is calculated in the same way as the CPR for air conditioning and mechanical ventilation, but with three additional sets of data, two for the heating system and one for the lighting. The equation for CPR(HLAC) is CPR(hlac) (PD x HD x CD x FD) + (PR x HR x CR x FR) + (PB x HB x CB x FB) + (PH x HH x CH x FH) + (PL x HL x CL x Fl) As before, the terms PD, HD, CD and FD refer to the mechanical...

The carbon performance rating for mechanical ventilation

The value of CPR(MV) is found from four components PD The total installed capacity of the fans which provide mechanical ventilation. This is expressed as the sum of the input kW ratings per square metre of the floor area of the treated space, kW m2. HD The typical annual equivalent hours of full load operation, assumed to be 3700 hours per year. CD The carbon emission factor, in kgC kWh, for the fuel used to power the fans. This is nearly always electricity, for which CD 0.113. FD A plant...

The Conservation of Fuel and Power in Dwellings

Part L1 of Schedule 1 to the 2001 Regulations is concerned with the conservation of fuel and power in dwellings. This is supported by Approved Document L1 which covers the following topics Compliance by the elemental method Compliance by the target U-value method Compliance by the carbon index method Limiting thermal bridging and air leakage Space heating controls and hot water systems Commissioning, operating and maintenance of heating and hot water systems Insulation of pipes and ducts The...

The elemental method applied to extensions to dwellings

Unlike other methods, the elemental method can be applied to an extension to a dwelling. If the target U-value or the carbon index method is used, the extended dwelling must be considered as a whole, and the method applied to the complete newly enlarged structure. However, when applied to extensions, the elemental method does allow some flexibility. The ways in which the requirements can be satisfied are Adhere to the maximum U-values given in Table 2.1 for all elements in the extension,...

The importance of airtightness

It has long been recognised that buildings, even when all doors, windows and other openings are closed, are not fully airtight. Wind forces create pressure differences which give rise to an unquantifiable and often unwanted air flow through a building, usually called air infiltration to distinguish it from planned ventilation. In cold weather, air infiltration leads to an additional heat load and may also cause discomfort due to cold draughts. In hot weather, it can disturb the temperature...

The legal requirement for the conservation of fuel and power in dwellings

The legal regulation requires that a dwelling should be so designed and constructed as to make reasonable provision for the conservation of fuel and power, and that this shall be achieved by attention to all of the following four points Limiting heat loss through the fabric of the building, from hot water pipes, from air ducts used for space heating and from hot water vessels Ensuring that the space heating and hot water systems which are provided are energy efficient Ensuring that internal and...

The measurement of air leakage

The equation for the leakage flow rate for a complete building will be similar to the equations given in section 14.2.1 above for individual components, and so may be expected to be of the form where Q is the overall leakage flow rate k is a constant which is a measure of the overall effective leakage area Ap is the pressure difference across the fabric of the building n is an index. Examination of the formulae in 14.2 above suggests that the index n is somewhere in the range 0.5 to 1.0. Its...

The Part L standard

To avoid some of the difficulties of measurement and interpretation, Part L of the Building Regulations has chosen a relatively simple criterion for deciding whether or not a building is sufficiently airtight. It first assumes that the fan pressurisation method provides a more reliable test of the airtightness of a building than the tracer gas, or any other, method. It then takes the experimentally determined flow rate at a pressure difference of 50 pascals as being the most reliable measure of...

The provision of hot water systems in dwellings

Although there are several acceptable ways of providing hot water, AD L1 provides guidance only for systems which include integral or separate hot water storage. Possible ways of satisfying the requirement, together with the relevant standards, are given in Table 2.5. Table 2.5 Standards for hot water systems. Meet the insulation standards of the most appropriate of these listed standards BS 1566 22 BS 699 23 BS 3198 24 BS 7206 25 In ordinary cases, use insulating vessels with a factory-applied...

The wholebuilding method

This method is separate and independent of the elemental method and therefore allows much more design flexibility. To show compliance it must be shown that Either the total carbon emissions Or the primary energy consumption for the complete building are reasonable for the purposes of conserving fuel and power. Three building types are considered in AD L2, though for all three types the details and calculation procedures are given not in AD L2 but in other publications.

Thermal conductivity and density of building materials

Table 4.16 lists the thermal conductivities and densities of some common building materials. Table 4.16 Thermal conductivity and density of common building materials. Table 4.16 Thermal conductivity and density of common building materials. Lightweight aggregate concrete block Concrete, medium density (inner leaf)

Tradeoff between construction elements and heating system efficiency

Throughout AD L2, rate of carbon emissions is taken to be an indicator of whether or not the requirement to conserve fuel and power has been met. Consequently, the elemental method allows the designer to trade off, in either direction, between the U-values of the building envelope and the carbon intensity of the heating system, provided the rate of carbon emissions is unchanged (or, although AD L2 does not specifically say, less). Compliance may be demonstrated by adjusting the area-weighted...

Uninsulated suspended ground floors

The U-values for uninsulated suspended ground floors are given in Table 6.3. These values can be used when The floor deck is not more than 500 mm above the external ground level The wall surrounding the underfloor space is uninsulated. Table 6.3 U-values for uninsulated suspended ground floors. Ventilation opening area per unit area of underfloor space Perimeterto 0.0015 m2 m 0.0030 m2 m m m2 U-value of suspended ground floor, W m2K Ventilation opening area per unit area of underfloor space...

Values for FR

Values for FR also depend on a combination of plant management features and monitoring and reporting features, and must be obtained from Table 12.2. Provision of energy metering of plant and or metering of plant hours run, and or monitoring of internal temperature in zones, plus the ability to draw attention to out-of-range values Provision of energy metering of plant and or metering of plant hours run, and or monitoring of internal temperature in zones Variation of fresh air using economy...

Values of qsw and qsr

The solar loads, qsw and qsr, are averages between 07.30 in the morning and 17.30 in the evening. A single value of qsr is suitable for all horizontal surfaces (i.e. rooflights) For vertical surfaces (i.e. windows) the value of qsw depends on orientation and must be obtained from Table 13.1. Table 13.1 Average solar load, windows. Table 13.1 Average solar load, windows.

Wind induced pressure difference

Relative to the static pressure of the free wind, the time averaged pressure, Apw, acting on the surface of a building is Cp is an experimentally determined pressure coefficient vh is the wind velocity at a reference height, usually taken as the height Meteorological data usually quotes wind speeds at a standard height of 10 m, and so vh must be estimated from this meteorological wind speed. Near the earth's surface, the wind speed follows a power law where vm is wind velocity at a height of 10...

Windows doors and rooflights

Provide units that meet the requirements for new buildings, or Provide units with a centre-pane U-value no worse than 1.2 W m2K. The replacement work should comply with the requirements of both Part L2 and (unless non-glazed fittings are involved) Part N. In addition, after the work the building should not have a worse level of compliance with other relevant parts of Schedule 1, such as Parts B, F and J. However, note that the requirement does not apply to repair work on parts of these...

Air permeability and infiltration rate

Approximate formulae relating the flow rate at 50 pascals to the measured infiltration rate at various average wind speeds have been given by Liddament 60 . These formulae apply mainly to small buildings, especially dwellings, and after some manipulation may be expressed in terms of the air permeability For Z measured at high average wind speeds (> 4 ms 1) AP50 For Z measured at typical average wind speeds, AP50 For Z measured at low average wind speeds (< 4 ms 1) AP50 where Z is the...

Example calculations for walls

Figure 4.4 shows a masonry cavity wall. The maximum U-value allowed by the elemental method is, from Table 2.1, 0.35 W m2K, and it is required to determine the necessary thickness of expanded polystyrene board (EPS) insulation, of thermal conductivity 0.040 W mK. From Table 4.5, there are no AU reductions, and so Now use Tables 4.8 and 4.9 to find the base thickness and the allowable reductions. Note that the reduction for 150 mm of 600kg m3 blockwork is 1.5 x 17 25.5mm. As this is a reduction,...

Lighting efficiency standards

AD L2 states that lighting systems should be reasonably efficient and, where appropriate, make effective use of daylight. Beyond this statement there is no further mention of daylight, and hence no guidance as to what level of daylight provision might be considered effective and acceptable. AD L2 is, however, concerned with conserving the energy used by electric lighting systems. The efficiency and the control of lighting systems are considered separately, and the guidance varies according to...

Preparation for a fan pressurisation test

The pressurisation test must be carried out on the completed building. Details of the recommended test procedures and the instrumentation are given in CIBSE TM 23 21 . The following points relate to preparation of the building and the Determine the exact boundaries of the external envelope of the building that is to be tested. Service spaces such as boiler rooms, lift rooms or rooms housing switch gear, may be taken as outside the space to be tested. Adjoining buildings, connected for example...

Values of fc

The correction factor for the glazing blind combination, fc, may either be selected from Table 13.2, or obtained from the appropriate shading coefficients. The shading coefficients for various glazing and shading device combinations Table 13.2 Correction factor for glazing blind combinations. Glazing blind combination from inside to outside 0.95 0.62 0.66 0.92 0.60 0.62 0.69 0.47 0.50 0.56 0.37 0.39 0.57 0.47 Blind clear reflecting Blind clear absorbing Blind low-e clear Blind low-e reflecting...

Example Solid ground floor over clay subsoil with vertical edge insulation

The floor in Fig. 6.2 is provided with vertical edge insulation instead of all-over insulation. The insulation is to a depth of 750 mm, and the insulation is 75 mm thick with a thermal conductivity of 0.040 W mK. The resistance of the insulation layer is From Example 6.1, the perimeter to area ratio of this floor is 0.57, and its uninsulated U-value is 0.74 W m2K. We require the edge insulation factor from Table 6.2, and it is necessary to interpolate between the columns for Rins 1.5 and Rins...

The elemental method for dwellings

In the elemental method, compliance is demonstrated by specifying Maximum U-values for walls, floors and roofs Maximum area-weighted U-values for windows, doors and rooflights Maximum combined area of windows, doors and rooflights Minimum boiler efficiencies for the heating system boiler the SEDBUK rating, or Seasonal Efficiency of a Domestic Boiler in the UK . The maximum U-values allowed by the elemental method are shown in Table 2.1, and are illustrated in Fig. 2.2. If an element is exposed...

The importance of thermal bridges

Thermal bridges are areas of increased heat flow across otherwise thermally insulating materials or constructions. They are a particular problem in building construction because it is rarely possible to provide a perfectly continuous and unbroken layer of insulation around the whole of the space which is to be insulated. In addition to the increased heat flow, a thermal bridge also has an effect on surface temperatures, creating in winter a drop in surface temperature on the inner warm side of...

Conservatories

Roof spaces adjacent to a room in a roof. Xhese values, which are shown in Xables 5.3 and 5.4, can also be applied to similar situations in other buildings. For other unheated spaces it may be possible to calculate Rextra from where AINX is the total area of the elements separating the internal heated space from the unheated space, and AEXX is the total area of the elements separating the unheated space from the outside. However, if this formula yields a result for Rextra greater than 0.5 W...

Example calculation

Perimeter Zone And Inner Zone

Part of the top floor of a college building is used as a studio for student art classes. The room is 14m x 7m on plan, with a floor to ceiling height of 3 m. One of the long walls is an external wall facing south-west with four windows, each 2.5 m wide by 1.5 m high. The window frames have a framing ratio of 20 of the window area. Daylight along the long internal wall is provided by a line of six horizontal rooflights, each 1m square, with a framing ratio of 25 . The centre line of the...

The target Uvalue method for dwellings

In order to demonstrate compliance using the target U-value method, it is necessary to calculate and compare two U-values. The first, UT, is a target U-value. This is a theoretical index which is calculated from an initial basic formula, and which is then adjusted to allow for any design features that affect the energy consumption of the dwelling. The second, UAVG, is the area-weighted average U-value of the actual dwelling, taking into account all exposed surfaces including walls, floors,...

Infrared thermography

Infrared thermography uses specially designed infrared video or still cameras that convert the infrared radiation into images that show surface heat variations. The technique has applications in a variety of fields, including medicine, electrical installations, cold storage facilities, etc. When applied to buildings, it can be used to examine the whole or part of the exterior envelope, or it can be used to look at surface temperatures within a building. When used to identify thermal bridges, it...

Example calculations for roofs

Ceiling Insulation Thickness

Example 4.1 Pitched roof with insulation between the joists Figure 4.2a shows insulation laid between the ceiling joists of a pitched roof which is covered with 19 mm roof tiles. The maximum U-value allowed by the elemental method is, from Table 2.1, 0.16W m2K, and it is required to determine the necessary thickness of insulation. First, from Table 4.5, there is a AU correction of 0.01 W m2K. The design or 'look-up' U-value is therefore a Insulation between ceiling joists a Insulation between...

Q CPR Calculations Methods for Office Buildings

The carbon performance rating CPR calculation method is a simple technique, derived from three sources, for assessing the amount of carbon emitted into the atmosphere in units of kgC m2 year. It is used within the elemental method for assessing the contribution to carbon emissions arising from the operation of mechanical ventilation and air conditioning systems. It is also used in the whole-building method for offices in order to assess the total emissions due to mechanical ventilation, air...

Auau R

In this wall, the fixing of the mineral wool insulation in its timber sub-frame is such that there is no air movement on the warm side, but there are some air gaps penetrating the insulation layer. As the air gaps are in the mineral wool and timber sub-frame, Rl Rit 1.815. Referring to Table 5.1, the correction for air gaps is level 1, and so AU11 0.01. With RT 3.170, the correction is thus As this is less than 3 of U, it may be ignored. The final U-value is rounded to two decimal places Figure...

Background theory

The lower the U-value of a construction element, the more significant is the effect of thermal bridging on the calculation of the U-value. Consequently it is usually necessary to include thermal bridging in the calculation method. The theory is based on the calculation of thermal resistances. For a single layer of material, the thermal resistance R is given by where d is the thickness of the layer in metres, and X is the thermal conductivity. The combined resistance of several materials depends...

Reasonable provision of energy meters and submeters

Reasonable provision of meters would be to install incoming meters in every building greater than 500 m2 gross floor area including separate buildings on multi-building sites . This would include Individual meters for direct measurement of the total electricity, gas, oil and LPG consumed by a building A heat meter capable of direct measurement of the total heating and or cooling energy supplied to the building by a district heating or cooling scheme. In the case of sub-metering, it would be...

Roof window

Door, glazed to more than 50 of its total area, including its frame, measured internally Space heating or hot water service boiler Part L1 applies to replacement work on controlled services or fittings when Replacing old with new identical equipment Replacing old with new but different equipment The work is solely in connection with controlled services or includes work on them. Ways of satisfying the requirements of Part L1 may depend on the circumstances of the particular case. Specific...

Values for FD

Values for FD depend on a combination of plant management features and monitoring and reporting features, and must be obtained from Table 12.1. In this table, values are selected from the most relevant column. If it is appropriate to select more than one value from that column, then the final value of FD is the product of the selected values. Provision of energy metering of plant and or metering of plant hours run, and or monitoring of internal temperature in zones, plus the ability to draw...

Stack effect pressure difference

The stack effect is the pressure due to the difference between inside and outside temperatures, over a pair of openings at different heights. The natural pressure gradient in the air due to height is different inside and outside the buildings because the air density is different. The net stack effect pressure difference, Aps, between the two openings is given by where g is the acceleration due to gravity h2-h1 is the difference in height between the two openings Text and Tint are the external...

Correction for mechanical fasteners

Xf is thermal conductivity of the fastener nf is number of fasteners per square metre Af is cross-sectional area of one fastener a is obtained from Table 5.2. Table 5.2 Corrections for mechanical fasterners. Table 5.2 Corrections for mechanical fasterners. Reproduced with permission from BS EN ISO 6946 Reproduced with permission from BS EN ISO 6946 Corrections for fasteners must not be applied when The wall ties are across an empty cavity The wall ties are between a masonry leaf and timber...