GUIDANCE SHEET FOR CONSERVATORIES, SUNROOMS AND EXTENSIONS TO DWELLINGS. This leaflet provides guidance on how to attain compliance with The Building (Amendment) Regulations (Northern Ireland) 2006, Part F1, Conservation of Fuel and Power in Dwellings. The following are the main areas of consideration, (but should not be read in isolation), when extending a dwelling. 1. Where the extension is a conservatory and is NOT exempt from the Building Regulations, it shall have: o Effective thermal separation from the dwelling by having separating walls, doors and windows between the dwelling and the conservatory that are insulated and draught-proofed to at least the same standard as the same elements in the existing dwelling; o Glazed elements that comply with: Table 3.1, and thermal elements that comply with: Table 3.2 o Where a heating system is installed, it shall comply, (see separate leaflet on heating systems). The heating system in the conservatory shall have independent on/off and temperature controls. 2. Where the extension is highly glazed, such as a sunroom, and complies with the above items, including separation, U-values and heating controls, it may be treated in a similar manner to a conservatory. 3. Where the highly glazed extension, such as a sunroom, is NOT thermally separated it shall be treated as a conventional extension and should demonstrate compliance in one of the following 3 ways: A) Standards Based Approach o Window and door area restricted to 25% of floor area (plus the area of existing that will be removed because of the extension). o New window and door U-values to comply with Table 3.1. o New thermal elements to have U-values that comply with Table 3.2. o Replacement thermal elements to have U-values that comply with Table 3.2. o Renovated thermal elements to have U-values in compliance with Table 3.3. o Retained thermal elements with a U-value greater than the threshold value in Table 3.3, to have U-values in compliance with Table 3.3. o Use accredited construction details (which are available at http://www.planningportal.gov.uk) o The accredited details will require that all cavities are maintained and that insulation is continuous, avoid thermal bridges, gaps etc. o Heating to comply with F1 standards see additional leaflets. 1
o Lighting 25% of new internal fittings to be energy efficient and external fixed lighting restricted to 150W o Provide sufficient operating instruction (for appliances etc), to end user. B) Calculated Trade-off Approach o The above standard fabric values and opening areas can be varied provided that: I. the area-weighted U-value of all the elements is calculated and does not exceed values for a notional extension of the same shape and size that complies with the U-values given in Table 3.1 to 3.3 II. the area-weighted U-value for each element type is not greater than Table 3.4 III. the maximum U-value of an individual element or part of is not greater than Table 3.4 NOTE: REFERAL TO A QUALIFIED DESIGNER IS RECOMMENDED FOR THIS CALCULATION, AS THE EVIDENCE IS TO BE PRESENTED TO BUILDING CONTROL. C) Equivalent Carbon Target Approach. o SAP 2005 calculation is required to be presented to Building Control to demonstrate that the calculated carbon dioxide rate from the dwelling and proposed extension is no greater than for the dwelling with a notional extension of the same shape and size complying with the Standards Based Approach above. If existing dwelling U-values are unknown SAP Appendix S shall be used to estimate the performance values so that area-weighted U-values can be calculated, to comply. o This method may require additional upgrades of the existing dwelling to compensate for lower performance in the extension. The standards for upgrading retained thermal elements are given in Table 3.3. NOTE: SPECIALIST WITH RELEVANT COMPUTER PROGRAM CAN CARRY OUT SAP CALCULATION. In all 3 cases above, YOU will be required to provide the information as proof of compliance, to Building Control. Definitions. Thermal Element: Elements such as external walls and roofs etc., that is required to give a thermal performance. Retained Thermal Element: An existing element, that becomes part of the thermal envelope where previously it was not. Renovated Thermal Element: Where more than 25% of the surface area of a thermal element is being renovated. Replacement Thermal Element: Thermal elements constructed as replacements for existing elements. 2
APPENDIX A - Tables Table 3.1 Standards for controlled fittings maximum U-values {W/(m² K)} or Window Energy Rating (WER) Fitting Windows, roof windows and roof lights Doors with more than 50% of their internal face glazed New fittings (in an extension or change of use) U-value = 1.8 or WER* = Band D or U-value = 2.2 or Replacement fittings (in an existing dwelling) U-value = 2.0 or WER' = Band E or U-value = 2.2 or Other doors U-value = 3.0 U-value = 3.0 NOTES: *See CE66, Windows for new and existing housing. Table 3.2 U-values for thermal elements {W/(m² K)} Element New elements (in an extension or change of use) Replacement elements (in an existing dwelling) Wall 0.30 0.35* Pitched roof (horizontal insulation at ceiling level) Pitched roof (inclined insulation at ceiling level) Flat roof or roof with integral inclined insulation 0.16 0.16 0.20 0.20 0.20 0.25 Floors* 0.22 0.25* NOTES: *Where meeting the above standards would cause a significant (5%) reduction in floor area or cause problems in relation to adjoining floor levels these values may be exceeded provided that compensating provisions are made. 3
Table 3.3 U-values for retained thermal elements {W/(m² K)} Element¹ Threshold U-value Improved U-value Cavity Wall² 0.70 0.55³ Other wall types 0.70 0.35 Pitched roof insulation at 0.35 0.16 ceiling level Pitched roof insulation at 0.35 0.20 rafter level Pitched roof with integral 0.35 insulation or flat roof Floor⁴ 0.70 0.25⁵ NOTES: 1 Roof includes the roof parts of dormer windows and wall includes the cheeks of dormer windows 2 Where a cavity wall is unsuitable for cavity insulation it shall be treated as Other wall type 3 A lesser provision may be appropriate where meeting such a standard would result in a reduction of more than 5% in the internal floor area of the room bounded by the wall 4 The Uvalue of the floor may be calculated using the exposed perimeter and floor area of the enlarged building 5 A lesser provision may be appropriate where meeting the standard would create significant problems in relation to adjoining floors Table 3.4 Limiting U-values {W/(m² K)} Element Area-weighted average U-value Maximum U-value Wall 0.35 0.70 Floor 0.25 0.70 Roof 0.25 0.35 Windows, roof windows*, 2.20 3.30 roof lights* and doors NOTES: * Where a roof window or roof light has been assessed in a plane other than the vertical, the U-value shall be modified by making a U-value adjustment in accordance with BR443: Conventions for U-value calculations. 4
APPENDIX B Examples NOTE: Examples are based on Polyisocyanurate, Rigid Phenolic or Rigid Urethane board with thermal conductivity of 0.023. o Pitched Roof with Flat Ceiling (U-value 0.16) When using a Glass Mineral Fibre or other insulation with thermal conductivity of 0.040 W/mK, an example is 100mm of insulation between the joists AND 170mm over the joists, (laid at right angles). o Sloping Ceilings with Insulation at Rafter Level (U-value 0.20) conductivity of 0.023 W/mK, an example is 120mm of insulation between the rafters AND 25mm across the face (above the plasterboard). o External Cavity Walls (U-value 0.30) conductivity of 0.023 W/mK, an example is 65mm of insulation in the cavity as partial fill. o Solid Floors (U-value 0.22) (P/A = 0.8) conductivity of 0.023 W/mK, an example is 70mm of insulation, this is roughly equivalent to 120mm of EPS. o Windows (U-value 1.8) When fitting new windows, ask the supplier to provide proof that the windows meet a U-value of 1.8 DISCLAIMER: This document has been prepared for use as an aid in compliance with the new Part F1 Regulations. It should be used solely as guidance and should not be treated as a Deemed to Satisfy document. NOTE: The above requirements are in ADDITION to the existing legislation. 5