Contents

6.0 Introduction
6.1 Objective
6.2 Building fabric - limiting energy use
6.3 Building services - heating system efficiency
6.4 Building services - insulation of pipes, ducts and vessels
6.5 Building services - artificial and display lighting
6.6 Building services - mechanical ventilation and air conditioning
6.7 Commissioning building services
6.8 Written information

Annexes

6.A Tables of U-values and thermal conductivity
6.B Worked examples of U-value calculations using the combined method
6.C U-values of ground floors and basements
6.D Thermal bridges at the edges of openings
6.E Compensating U-values for openings
6.H Alterations and extensions
6.J Heat Loss Method example and worksheet 6.J.4
6.K Example lighting calculations
6.L Performance assessment methods for office buildings
6.N Conversions
6.P Elemental U-values for limited-life buildings (without sleeping accommodation)

Introduction 6.0
guidance

6.0 Introduction
6.0.1 Background
6.0.2 General guidance for non-domestic buildings
6.0.3 Thermal conductivity
6.0.4 Thermal transmittance and the insulation envelope
6.0.5 Buffering effects of certain structures on the insulation envelope
6.0.6 Zero thermal transmittance and the insulation envelope
6.0.7 Roofs that perform the function of a floor
6.0.8 Atria
6.0.9 Annexes to guidance
6.0.10 Calculation of areas
6.0.11 Latest changes

6.0.1 Background

The construction industry has a major role to play in the conservation of fuel and power. Carbon dioxide emissions from the burning of fossil fuels are contributing to climate change and energy use in buildings is a significant source of emissions. Rising temperatures, an increased risk of flooding and sea level rise are some of the expected impacts of climate change on Scotland and the UK, but some of the worst impacts of climate change can be avoided if action is taken to reduce reliance on fossil fuels. Increased energy efficiency and promotion of renewable energy are an important element of Scotland's strategy to tackle the threat of climate change.

The intention of Section 6 is to ensure that effective measures for the conservation of fuel and power are incorporated in a building. It contains energy conservation provisions for the building fabric and the building services. In 2001 the UK Government introduced the Climate Change Levy on non-domestic energy use. By reducing energy consumption in such buildings, the impact of this tax will be lowered. The guidance given in this Section will go some way to achieving this, however nothing here prevents a building from being designed and constructed to be even more energy efficient and consequently, both the monetary and environmental savings will be improved.

All buildings that are not exempted by either Regulation 3, Schedule 1 or the Limitations, Schedule 5 relating to this Section, are required to conform to standards for energy efficiency. For building fabric insulation, there is a variety of guidance, ranging from the simple calculation of the heat losses through each building element, to more sophisticated methods that give greater flexibility to designers. The energy efficiency of building services, their controls and finally their commissioning must also be taken into account.

This Section should be read in conjunction with all the appropriate guidance to the Building (Scotland) Regulations 2004 but in particular Section 3: Environment has a close affiliation with energy efficiency, regarding:

• ventilation of buildings.
• combustion air and cooling air for combustion appliances

6.0.2 General guidance for non-domestic buildings [Reg 22(2)a, CRD141]

This Section covers the energy efficiency for non-domestic buildings. Such buildings include; factories, offices, shops, warehousing, hotels, hospitals, hostels, and also those used for assembly and entertainment. When determining how the Scottish Building Regulations’ guidance for energy efficiency applies to non-domestic buildings, recognition should be given to the following:

1. An insulation envelope is only appropriate to those parts of a building that are intended to be heated or cooled. Heating rated at a maximum of 25 W/m² of floor area and installed for the purposes of frost protection should be disregarded, for the purposes of this guidance.
2. Some concessions in terms of the insulation envelope are given to limited-life buildings that do not contain sleeping accommodation (see 6.0.4 f., 6.0.5 c. and Annex 6.P).

6.0.3 Thermal conductivity [J2.1]

The thermal conductivity (the k-value) of a material is a measure of the rate at which that material will pass heat and is expressed in units of Watts per metre per degree of temperature difference (W/m·K). Establishing the thermal conductivity of materials in an exposed building element will enable the thermal transmittance of the element to be calculated.

Measurements of thermal conductivity should be made in accordance with BS EN 12664 or BS EN 12667. Annex 6.A gives the thermal conductivity of some common construction materials, but when available, preference should be given to values that are certified by a notified body. The additional guidance given in the Building Research Establishment (BRE) publication BR 443 — ‘Conventions for U-value calculations’ can also be followed.

6.0.4 Thermal transmittance and the insulation envelope [J2.1] [CRD141]

Thermal transmittance (the U-value) is a measure of how much heat will pass through one square metre of a structure when the air temperatures on either side differ by one degree, and is expressed in units of Watts per square metre per degree of temperature difference (W/m²K).

Measurements of thermal transmittance should be made in accordance with BS EN 8990. Thermal bridging may be disregarded where the difference in thermal resistance between bridging and bridged material is less than 0.1 m²K/W. Normal mortar joints need not be taken into account in calculations for brickwork, but should be taken into account for lightweight insulating blockwork, for example.

Taking into account guidance as appropriate from BRE publication BR 443 — ‘Conventions for U-value calculations’, individual U-values of exposed building elements forming the insulation envelope should be established:

1. by using insulation to a thickness derived from manufacturers' data relating to thermal conductivities (W/m·K) and thermal transmittances (U-values: W/m²K) certified by a notified body; or
2. by using insulation to a thickness derived from the tables in Annex 6.A; or
3. by calculation taking into account thermal bridging effects of, e.g. timber joists, structural and other framing, normal bedding mortar and window frames, by using the Combined Method set out in BS EN ISO 6946 or CIBSE Guide Section A3, 1999 Edition (for worked examples see Annex 6.B); or
4. for floors adjacent to the ground and basement storeys, by using the method outlined in Annex 6.C and set out fully in BS EN ISO 13370 or CIBSE Guide Section A3, 1999 Edition; or
5. for glazing, by using BS EN ISO 10077-1 or prEN ISO 10077-2 or the tables in Annex 6.A; however
6. for limited-life buildings which do not contain sleeping accommodation, elements containing repeating thermal bridges may be calculated in accordance with the proportional method set out in CIBSE Design Guide A: 1980, Section A3.

6.0.5 Buffering effects of certain structures on the insulation

envelope [J2.3] [CRD141]

The following should be considered where a non-domestic building (or part) is separated or divided from an enclosed area that:

• Is neither heated nor cooled, or
• Is heated or cooled to a significantly different level.

Examples of such areas could be in the first instance, an unheated carparking garage which is adjacent to office accommodation and for the second case, a cold store which is adjacent to a space heated part of a factory. In such cases the separating walls and floors or dividing walls and floors should have fabric insulation. This can be achieved by one of the following ways:

1. by disregarding the ‘buffering’ effects of the area and treating the U-value of the separating/dividing element as if it were directly exposed to the external air; or
2. by following the procedure in BS EN ISO 13789.
3. for limited-life buildings which do not contain sleeping accommodation, by adopting a U-value of 0.6 for such an element.

Please note that doors or windows that occur in such elements should achieve the levels specified in Table 1 to 6.2.1 — (Elemental Method) unless the separating/dividing element forms a part of either the Heat Loss or Carbon Emissions Calculation Method.

For guidance on atria, see 6.0.8 below.

6.0.6 Zero thermal transmittance and the insulation envelope [J2.4]

Thermal transmittance through separating walls or separating floors between 2 units in different occupation should be ignored, if it is likely that both parts will be heated or cooled to a similar degree.

6.0.7 Roofs that perform the function of a floor [J2.2]

For the purposes of establishing the exposed building element status, a roof of a building that also performs the function of a floor or similar load-bearing surface (e.g. an access deck, escape route, roof garden or car park), should be considered as a roof.

6.0.8 Atria [J2.3]

In a building with an atrium, the guidance given in 6.0.5 above, only applies if the atrium is unheated and totally divided from the remainder of the building by, glazing and doors and if appropriate, walls and floors. In addition to this, it should not be intended that the atrium is to gain heat transfer from the surrounding building. In other situations involving atria, where none of this occurs, the insulation envelope is at roof level (usually predominantly glazed) and the atria is considered to be a part of the main building.

6.0.9 Annexes to guidance

At the back of the main guidance document are the Annexes. These have a dual role. Some give guidance in respect of calculation procedures. Others however, show how the guidance should be applied to buildings in the form of, alterations, extensions, historic buildings and conversions.

6.0.10 Calculation of areas [J2.5]

When calculating areas, for the purposes of this Section and in addition to Regulation 7, Schedule 4, the following should be observed:

1. All areas should be measured in m², unless stated otherwise in the guidance.
2. The area of a floor, wall or roof is to be measured between finished internal faces of the insulation envelope, including any projecting bays and in the case of a roof, in the plane of the insulation.
3. Floor areas are to include stairwells within the insulation envelope and also non-useable space (for example service ducts).
4. The area of an opening should be measured internally from ingo to ingo and from head to sill or threshold.

6.0.11 Latest changes

The Circular referred to in Standard 6.1 is required due to the change from mandatory Technical Standards to Guidance.

Heating system — Standard 6.3. The previous Technical Standards only permitted heating systems with a higher carbon intensity (e.g. electric resistance heating) in a building by way of a tortuous route through the Carbon Emissions Calculation Method. Clause 6.3.2 now gives a trade-off against building fabric and can be used with either the Elemental Method or the Heat Loss Method.

Annex 6.H on alterations and extensions is provided to help building designers and building control officers determine an appropriate approach to dealing with building work to existing buildings that are currently less than ideal in terms of energy efficiency. One significant addition is that instead of heating systems with a higher carbon intensity being prevented from being installed in an existing building, it is now possible to compensate by upgrading the fabric insulation.

Annex 6.N on conversions is provided to help building designers and building control officers determine an appropriate approach to dealing with conversions to existing buildings that are currently less than ideal in terms of energy efficiency. One significant addition is that buildings that are converted (schedule 2), and also which were heated in their existing state) should meet certain levels of fabric insulation.