BEDROOM
KITCHEN
LIVING ROOM
BATHROOMRetrofitting
historic
buildings
Consultation draft
January 2011
Retrofitting
historic buildings
Consultation draft
January 2011
Contents
1. Introduction
4
2. Case Studies and tables of measure
9
1. Unlisted properties in a conservation area
10
2. Grade II listed properties
16
3. Unlisted properties outside conservation area
21
Introduction
Our buildings are the single biggest contributor to the UK’s Carbon Dioxide
emissions. With stretching UK commitments to an 80% reduction in CO
2emissions by 2050, and the large number of existing buildings expected to
still be standing in 2050, we cannot rely on improved performance of new
buildings alone to do this; it can only be met by undertaking a programme of
retrofitting existing buildings, including historic buildings, to ensure they are
fit for the future. This guidance is consistent with the national planning policy
statements PPS1 Delivering Sustainable Development; PPS1 supplement,
Planning and Climate Change and PPS5 Planning for the Historic
Environment, and builds on the London Plan and the Council’s own Core
Strategy policy CS24 Heritage which says: ‘...Historic and other important
buildings should be upgraded sensitively, to improve their environmental
performance…’
The City Council is working with developers, businesses and residents to help shape a sustainable city where buildings of high environmental performance are common place. The sensitive and appropriate refurbishment of historic buildings, incorporating features of sustainable design, is key to delivering this vision in Westminster. This guidance is aimed primarily at pre-1940 properties of a solid wall construction, but many measures are equally applicable to later buildings.
Westminster is rich in historic buildings with 11,000 properties of listed status, in 56
conservation areas that encompass 75% of Westminster. Conservation of historic buildings is part of sustainable development, given the considerable amount of embodied energy in these properties. Appropriate refurbishment of historic buildings is a crucial part of their conservation to ensure they have a sustainable future. Improving the environmental performance of buildings and protection of the historic built environment are therefore complimentary objectives. Planning policies for both heritage conservation and sustainable design have a crucial role to play. So too does guidance to illustrate how, in practical terms, this balance can be achieved through the development management process.
The City Council has considered the most effective and sensible ways to upgrade the environmental performance of historic buildings, including those which are listed or in a conservation area. The aim of this document is to encourage the sensitive upgrading of historic buildings wherever possible by setting out guidance on what is appropriate, and where further advice, planning permission or listed building consent may be needed.
This document details a range of measures that might be suitable
in the following cases:
• An unlisted property in a conservation area • A listed property
• An unlisted property outside a conservation area.
Three tables list the retrofit measures which might be possible in each of the above cases, and set out information on likely heritage considerations, costs, carbon cost effectiveness and risks. A modelled example property has also been included to show the potential carbon savings that can be achieved.
The focus of the tables and case studies is on medium-high cost energy efficiency measures and low carbon or renewable energy generation measures, but it also considers measures to improve water efficiency and reduce flood risk by managing surface water runoff and also measures to increase biodiversity.
Limitations of this guidance
These tables are intended to illustrate the different approach that might be taken to retrofitting properties subject to varying levels of heritage protection. All properties are unique so
measures contained in this guidance are not necessarily recommended as appropriate for all properties. The notes in the conservation and design considerations and risks section should be carefully considered, and advice sought where there is any doubt. All costs are
approximate and will vary depending on many factors including location, condition of property, cost of labour etc.
Conservation areas
Conservation areas are areas of special historical or architectural interest where areas of distinctive townscape, buildings, spaces and other features of special interest are protected. In some conservation areas there may be further controls on development, including minor changes such as to external doors or windows. These are referred to as Article 4 Direction Areas1. In Westminster, the cost effectiveness of carbon saving measures should be weighed
up against the design and conservation considerations, as well as risks inherent in any physical intervention.
Listed Buildings are those included on the national register of Buildings of Special
Architectural or Historic Interest. These have special protection and require Listed Building Consent before they may be extended or altered (internally or externally).
Approach to retrofitting historic buildings
Before beginning to think about measures to retrofit to a property, it is necessary to
understand the building as it is already, to think about what simple changes can be made. Start by considering the following questions:
1 See further information on the Council’s website regarding the location of these areas at: http://www.westminster.gov.uk/services/environment/planning/permission/
1. How is the building used? Can it be used more efficiently? You should ensure that
you are already undertaking measures that can be implemented at no cost2, which
involve changes to behaviour rather than the building fabric, and very minor alterations and additions to make the building more energy efficient (see suggestions below).
THEN
2. Consider the type of heritage protection that applies and identify the relevant table. (See flowchart below). Consider measures suggested and whether they are
suitable for your property. Pay attention to risks, and heritage and conservation considerations. See the detailed information and signposts in section 3 and seek advice where necessary.
3. What is the budget? Consider the cost effectiveness, and the likely payback period
of measures that will have a medium to high cost.
4. Seek advice from planning and conservation officers on whether planning permission
and/or listed building consents are necessary and on the proposed measures and obtain these consents.
5. Undertake work, ensuring that any new systems are working effectively, and that
occupants understand how to use them efficiently.
THEN
6. Undertake regular maintenance.
Is your property a
listed building?
Is your property in a conservation area?
See http://www.westminster.gov.uk/
services/environment/planning/
conservationlistedbuildings/
areaprofiles/
See table 3
See table 2
See table 1
No Yes Yes NoLow cost measures
When upgrading historic buildings you should first consider these low cost measures which will have limited impact on the historic fabric and in most circumstances will not require permission from the City Council.
• Replace conventional light bulbs with low energy Compact Fluorescent Lamp (CFL) bulbs and halogen spotlights with lower energy alternatives.
• Insulate hot water tanks and pipes. A British Standard cylinder jacket of 75mm will cost around £12 and save you £35 a year in energy bills3.
• Draught proof doors and windows. If existing windows are in good repair then draught sealing can be effective in reducing heat loss, and fuel bills by up to £25 per year4.
• Repair and use original internal shutters where possible. Although not as effective as secondary or double glazing, they will reduce heat loss to some extent, as will closing the curtains.
• Use a removable chimney balloon or open/close chimney damper plates to minimise draughts.
• Select energy and water efficient appliances.
• Use a real time energy display, in a prominent location to give an overview of energy consumption and to help manage energy use.
3 Energy Saving Trust 4 Energy Saving Trust
Case studies and
tables of measures
The following tables set out a variety of measures which might be
undertaken to improve the energy efficiency of a property. These have been
grouped according to the type of heritage protection that applies. This will
give an indicative guide to what should be acceptable, and where further
discussion with a planning officer is necessary. Many of the energy saving
retrofit measures which appear in these tables will be equally suitable for all
properties in all locations, but for some measures more will be possible on
unlisted properties and those outside a conservation area.
Ratings have been given for typical cost, carbon cost-effectiveness
and disruption as follows:
Costs Symbol 0-£100 £ £100-£1000 ££ £1000-£5000 £££ £5000-10,000 ££££ over £10,000 £££££ Cost effectiveness Symbol
Pays for itself 0-10 £/tonne CO2
10-100 £/tonne CO2
100-500 £/tonne CO2
>500 £/tonne CO2
Disruption
This is rated from low-high, with high meaning that occupants would probably need to move out.
Costs are intended as a guide only and
will vary depending on specification,
actual property and local conditions.
This is the capital cost of the measure
minus the fuel cost savings that it will
deliver (over lifetime of 60 yrs), per tonne
of CO
2emission saved, over the lifetime
Measure Conservation considerations and permissions Typical cost (per unit or as specified) Building regs. application needed? Carbon cost-effectiveness Disruption Risks 1. Loft insulation – 300mm Permissions not normally required as long as it doesn’t alter the external appearance of the roof. ££ £22/m2 installed and DIY costs (If rockwall – must install minimum 270mm)
Low Low risk, if installing between existing rafters but ensure an air gap around edges of loft to avoid damp and allow air to circulate. 2. Floor insulation (raised timber floors)
Permission not required. As internal alterations of an unlisted property in a conservation area don’t require planning permission
££
£22/m2
High Low risk. Care needs to be taken if existing floor boards need to be lifted. Take care not to block air bricks under the floor, as air needs to circulate beneath a wooden floor to avoid damp and rot.
1. Unlisted properties
in a conservation area
EXAMPLE An unlisted two storey mews house in a
conservation area. This property can cut its emissions by up to 72% by undertaking the following measures:
• Roof insulation • Floor insulation
• Internal solid wall insulation
• Double glazing and upgrading roof light to building regulations standards • Draught-proofing and sealing
• Upgrading existing boiler
And a further 7% by:
• Installing 5.2m2 PV cells
Measure Conservation considerations and permissions Typical cost (per unit or as specified) Building regs. application needed? Carbon cost-effectiveness Disruption Risks 3. External solid wall insulation Planning permission needed. May be allowed in certain circumstances, but contentious; refer to Design and Conservation officer. Only likely to be acceptable on the rear elevation and then only in an enclosed situation not part of a unified terrace, where it does not cover up brickwork (so replaces/upgrades existing render); and the thickness and visual impact mean that details of the windows are maintained. £££££ £47-70/m2 / £10,600-14,600 for a typical 3 bed semi inc preparation and making good. Med High! Specialist advice should be sought. Consider the lifespan of the product. Reduced ventilation in older buildings can lead to moisture/damp problems, which can damage a building. 4. Internal solid wall insulation
Permission not required as internal alterations of an unlisted property in a conservation area don’t require planning permission
££££
£47-200/m2
but this will require a vacant property and possibly removal and refitting of kitchen and bathroom which adds a great deal to the cost. High High! Specialist advice recommended, due to possible moisture and ventilation problems 5. Secondary glazing
Permission not required as internal alterations of an unlisted property in a conservation area don’t require planning permission ££ Around £200-500 for average home Must not affect escape windows
Med Med. Existing original windows should be refurbished and secondary glazing installed where possible. Advice may be needed on ventilation and condensation.
Measure Conservation considerations and permissions Typical cost (per unit or as specified) Building regs. application needed? Carbon cost-effectiveness Disruption Risks 6. Double glazing Planning permission may be required. Not normally required on single family dwellings. Likely to be acceptable on all windows where detailed specification matches in appearance and materials the original. ££££ - £££££ Around £1,800 for a replacement double glazed timber sash window. No need if installer is FENSA approved
Med Med. Consider whether original windows can be refurbished (which is more cost effective) before considering double glazing where windows cannot be reconditioned. Advice may be needed on ventilation and condensation. 7. Upgrade to a high efficiency and low NOx boiler system and heating controls Planning permission may be required. Flue to be positioned in a visually discreet location on the rear elevation. Discuss with conservation officer. £££ £3,000 (Inc programmer, thermostats, thermostatic radiator valves, standard auto ignition) No need if installer is gas safe approved Med Low 8. Energy efficient lighting
Permission not required £ Low Low 9. Door and window draught proofing and seals
Permission not required. £ - ££ Depending on type of system and if DIY or professional
Low-med Med. Advice may be needed on ventilation and condensation. 10. Real time energy display monitors
Measure Conservation considerations and permissions Typical cost (per unit or as specified) Building regs. application needed? Carbon cost-effectiveness Disruption Risks 11. PV electric solar panels Planning permission may be required. Solar panels mounted on the rear existing roof in a discreet location. ££££ 5.2m2 for £6,000 Med Med Advice needed, and possibly a feasibility or structural survey. Ensure roof accessible for maintenance. Ensure roof structure will bear the weight of panels. Have a supply of replacement roof tiles in case these are broken during installation. 12. Hot
water solar panels
Planning permission may be required. Solar panels mounted on the rear existing roof in a discreet location £££ 5.2m2 for £3,500 Med Med Advice needed, and possibly a feasibility or structural survey. Ensure roof accessible for maintenance. Ensure roof structure will bear the weight of panels. Have a supply of replacement roof tiles in case these are broken during installation. 13. Micro combined heat and power (CHP) Planning permission may be required. Flue to be positioned in a discreet location. ££££ £3000-6000 Not if installed under competent person scheme Best suited to properties with a high heat demand Med-high Low
Measure Conservation considerations and permissions Typical cost (per unit or as specified) Building regs. application needed? Carbon cost-effectiveness Disruption Risks 14. Air source heat pumps Planning permission may be required. Noise may be an issue, seek advice. £££££ Not if installed under competent person scheme Best suited to well insulated, relatively air-tight properties. Med-high Low 15. Ground source heat pumps Planning permission may be required. ££££ Not if installed under competent person scheme Best suited to well insulated, relatively air-tight properties High Low 16. Water efficient fixtures and fittings
Permission not required £-££ CLG estimates the cost of provision at £125, but this is expected to fall. Waterwise estimate the cost of retrofitting at around £40.
N/a Low Low
17. Greywater recycling
Permission not required if any tank located internally. ££/£ CLG estimates £800-£2650 depending on whether for flats or house N/a 18. Permeable paving
Permission not required. ££ Can be 2-3 times the cost of
conventional paving.
Measure Conservation considerations and permissions Typical cost (per unit or as specified) Building regs. application needed? Carbon cost-effectiveness Disruption Risks 19. Planting in raised beds in garden
Permission not required. £ N/a Low
20. Water-butt for rainwater collection
Permission not required £
£30
N/a Low
21. Composter
Permission not required £ N/a Low
22. Internal space for waste and recycling storage
Permission not required N/a N/a Low
23. Living roof
Planning permission required. Likely to be acceptable on existing flat roofs in a discreet location (but seek advice for proposals for intensive living roofs which are suitable for walking on)
£££
£85/m2
N/a Med-high Med
Ensure the roof structure can bear the weight of substrate,
permeability of roof membrane by plant roots, and that any height of balustrade is sufficient, (where used as amenity space) 24. Living walls Planning permission required. May be allowed in certain circumstances on rear elevation. ££££ Variable, but around £500/ m2, less for larger areas
N/a Med Med
Type of system – cell based, need for irrigation etc? 25. Bird
box
Permission not required. Suggested on rear elevation.
£ N/a Low
26. Bat box Permission not required. Suggested on rear elevation.
Measure Conservation considerations and permissions Typical cost (per unit or as specified) Building regs. application needed? Carbon cost-effectiveness Disruption Risks 1. Loft insulation – 300mm Straightforward loft insulation laid between rafters is unlikely to require listed building consent or planning permission, as long as historic roof fabric is not disturbed. Seek advice from a design and conservation officer. ££ (If rockwall – must install minimum 270mm)
Low Low risk, if installing between existing rafters but ensure an air gap around edges of loft to avoid damp and allow air to circulate.
2. Grade II Listed property
Although they enjoy the highest level of statutory protection, there are many
ways in which you can sensitively upgrade listed buildings. Many of the most
cost-effective measures are unlikely to require permission, from the City
Council. However, when considering retrofitting a listed building, it is
recommended that you consult a conservation officer prior to undertaking
any works. The table below gives an indication of when listed building
consent or planning permission may be required but any works which affect
the special interest of a listed building may require permission.
EXAMPLE: A Grade II Listed top floor flat. This property can cut its emissions by up to 64% by undertaking the following measures
• Internal solid wall insulation 50mm to front and rear • Roof insulation 200mm
• Secondary glazing
• Draught-proofing and sealing • Upgrade boiler.
In addition it can cut a further 5% by installing
• 5.2m2 PV cells
Measure Conservation considerations and permissions Typical cost (per unit or as specified) Building regs. application needed? Carbon cost-effectiveness Disruption Risks 2. Floor insulation (solid floors)
May require listed building consent. Depends on existing floor. Seek advice from a conservation officer.
££ High Med. Care needs to
be taken if existing floor boards need to be lifted. Take care not to block air bricks under the floor, as air needs to circulate beneath a wooden floor to avoid damp and rot.
3. Internal solid wall insulation
Listed building consent is required. May be granted in certain circumstances, for example where original finishes have been lost. Seek advice from conservation officer.
££££
£47-200/m2
but this will require a vacant property and possibly removal and refitting of kitchen and bathroom which adds a great deal to the cost. Med High! Specialist advice recommended, due to possible moisture and ventilation problems 4. Door and window draught proofing and seals
Permission not normally required, if the system used is of minimal intervention, such as foam backed draught strips. £ £100-200 depending if DIY or professional
Med Med. Advice may
be needed on ventilation and condensation. 5. Upgrade to a high efficiency and low NOx boiler system with heating controls Planning permission and listed building consent may be required. The flue should be positioned in a visually discreet location on the rear elevation. Discuss with conservation officer. £££ £3,000 (inc programmer, thermostats, thermostatic radiator valves, standard auto ignition) No need if installer is Gas safe approved Med Low
Measure Conservation considerations and permissions Typical cost (per unit or as specified) Building regs. application needed? Carbon cost-effectiveness Disruption Risks 6. Energy efficient lighting
Unlikely to require listed building consent to modify existing light fittings. May be required for installation of new light fittings (such as those which involve making a hole in ceiling, e.g. downlighters).
££ Low Low
7. Secondary glazing
Listed building consent will be required, although will generally be acceptable. Ensure that no damage is caused to existing windows or to shutters (if present). £££ Around £200-500 for average home Must not affect escape windows
Med Med. Existing original windows should be refurbished and secondary glazing installed where possible. Advice may be needed on ventilation and condensation. 8. Real time energy display monitors
Permission not required. £ Low Low
9. PV electric solar panels
Listed building consent and planning
permission will be required. Solar panels will be acceptable in a discreet location where not visible from surrounding properties e.g. internal valley roof or flat wall behind a parapet.
£££
5.2m2 for
£6,000
Med Med. Advice
needed, and possibly a feasibility or structural survey. Ensure roof accessible for maintenance. Ensure roof structure will bear the weight of panels. Have a supply of replacement roof tiles in case these are broken during installation.
Measure Conservation considerations and permissions Typical cost (per unit or as specified) Building regs. application needed? Carbon cost-effectiveness Disruption Risks 10. Hot water solar panels
Listed building consent and planning
permission will be required. Panels will be acceptable in a discreet location where not visible from surrounding properties e.g. internal valley roof or flat wall behind a parapet.
£££
5.2m2 for
£3,500
Med Med. Advice
needed, and possibly a feasibility or structural survey. Ensure roof accessible for maintenance. Ensure roof structure will bear the weight of panels. Have a supply of replacement roof tiles in case these are broken during installation. 11. Micro Combined Heat and Power (CHP)
Listed building consent and planning permission will be required. Flue to be positioned in a discreet location. £££ £3000-6000 Not if installed under competent person scheme Best suited to properties with high heat demand Med-High Low 12. Air Source Heat pump
Listed building consent and planning
permission will be required. Noise may be an issue, seek advice
£££££ Not if installed under competent person scheme Best suited to well insulated, relatively air-tight properties Med-High Low 13. Ground source heat pump Planning permission and listed building consent may be required. £££££ Not if installed under competent person scheme Best suited to well insulated, relatively air-tight properties High Low
Measure Conservation considerations and permissions Typical cost (per unit or as specified) Building regs. application needed? Carbon cost-effectiveness Disruption Risks 14. Water efficient fixtures and fittings Permissions not required. £ CLG estimates the cost at £125. Waterwise estimate the cost of retrofitting at around £40.
n/a Low Low
15. Space for waste and recycling storage Permissions not required.
N/A n/a None Low
16. Living Roof
Listed building consent and planning
permission will be required. May be acceptable on existing flat roofs in a discreet location.
£££
£85/m2
n/a Med-High Med. Ensure the roof can bear the weight of substrate, permeability of roof membrane by plant roots, and that any height of balustrade is sufficient, (where used as amenity space) 17. Bird box
Permission not normally required if to rear elevation
£ n/a Low Low
18. Bat box Permission not normally required if to rear elevation
Measure Conservation considerations and permissions Typical cost (per unit or as specified) Building regs. application needed? Carbon cost-effectiveness Disruption Risks 1. Roof insulation – 300mm
Permission not normally required as long as it doesn’t alter the external appearance of the roof. ££ £22/m2 installed and DIY costs (If rockwall – must install minimum 270mm)
Low Low risk, if installing between existing rafters but ensure an air gap around edges of loft to avoid damp and allow air to circulate. 2. Floor insulation (solid floors)
Permission not required. ££ £22/m2
High Med. Care needs to be taken if existing floor boards need to be lifted. Take care not to block air bricks under the floor, as air needs to circulate beneath a wooden floor to avoid damp and rot.
3. Unlisted properties outside
Conservation Area
EXAMPLE An unlisted Victorian terraced house outside a conservation area. This property can cut its emissions by up to 55%.
• Internal insulation to front and rear • Floor insulation
• Install secondary glazing
• Upgrade boiler and heating controls • Draught-proof and sealing
In addition it can cut a further 6% by installing 5.2m2 solar
Measure Conservation considerations and permissions Typical cost (per unit or as specified) Building regs. application needed? Carbon cost-effectiveness Disruption Risks 3. External solid wall insulation
Permission not normally required on a single family dwelling. May be acceptable to rear elevation, where the thickness and visual impact mean that details of the windows are maintained. Discouraged where part of a group of properties of unified appearance. ££££ £47-70/m2 / £10,600-14,600 for a typical 3 bed semi inc preparation and making good. Med High! Specialist advice must be sought. Consider the lifespan of the product. Reduced ventilation in older buildings can lead to moisture/damp problems, which can damage a building. 4. Internal solid wall insulation
Permission not required. ££££
£47-200/m2
but this will require a vacant property and possibly removal and refitting of kitchen and bathroom which adds a great deal to the cost. High High! Specialist advice recommended, due to possible moisture and ventilation problems. 5. Door and window draught proofing and seals
Permission not required. £ £100-200 depending if DIY or professional
Med Med. Advice may
be needed on ventilation and condensation. 6. Secondary glazing
Permission not required. £££ Around £200-500 for average home Must not adversely affect escape windows
Med Med. Existing original windows should be refurbished and secondary glazing installed. Advice may be needed on ventilation and condensation.
Measure Conservation considerations and permissions Typical cost (per unit or as specified) Building regs. application needed? Carbon cost-effectiveness Disruption Risks 7. Double glazing Permission may be required. Double glazing likely to be permitted on all windows where detailed specification
demonstrates that new frames match existing in details and materials.
££££ Around £1,800 for a replacement double glazed timber sash window. No need if installer is FENSA approved
Med Med. Advice may be needed on ventilation and condensation. 8. Upgrade to a high efficiency and low NOx boiler system with heating controls
Permission not normally required. Flue to be positioned in a visually discreet location on the rear elevation. Discuss with conservation officer. £££ £3,000 (inc programmer, thermostats, TRV’s, standard auto ignition) No need if installer is Gas safe approved Med Low 9.Energy efficient lighting
Permission not required. £ Low Low 10. Real
time energy display monitors
Permission not required. £ Low Low
11. PV electric solar panels
Permission may be required. Solar panels in a discreet location. £££ 5.2m2 for £6,000 Med Med Advice needed, and possibly a feasibility or structural survey. Ensure roof accessible for maintenance. Ensure roof structure will bear the weight of panels. Have a supply of replacement roof tiles in case these are broken during installation.
Measure Conservation considerations and permissions Typical cost (per unit or as specified) Building regs. application needed? Carbon cost-effectiveness Disruption Risks 12. Hot water solar panels Permission may be required. Solar panels in a discreet location £££ 5.2m2 for £3,500 Med Med Advice needed, and possibly a feasibility or structural survey. Ensure roof accessible for maintenance. Ensure roof structure will bear the weight of panels. Have a supply of replacement roof tiles in case these are broken during installation. 13. Micro Combined Heat and Power (CHP)
Permission not normally required. Flue to be positioned in a discreet location. £££ £3000-6000 Not if installed under competent person scheme Best suited to developments with high heat demand. Low 14. Air source heat pumps Permission may be required. Noise may be an issue. Seek advice.
£££££ Not if installed under competent person scheme Best suited to developments with high heat demand. Med-high Low 15. Ground source heat pumps
Permission not required for single family dwelling. £££££ Not if installed under competent person scheme Best suited to developments with high heat demand.
Measure Conservation considerations and permissions Typical cost (per unit or as specified) Building regs. application needed? Carbon cost-effectiveness Disruption Risks 16. Living Roof Permission may be required. Not encouraged on front elevation £££ £85/m2 Med. Weight of substrate, permeability of roof membrane by plant roots and any balustrade is of sufficient height if used as amenity space. 17. Living walls Permission may be required. Likely to be acceptable on a rear elevation £££ Variable, but around £500/m2, less for larger areas
n/a Med-high Med. Type of system – cell based, need for irrigation etc?
18. Water efficient fixtures and fittings
Permission not required £ CLG estimates the cost at £125, but Waterwise estimate the cost of retrofitting at around £40.
n/a Low Low
19. Greywater recycling
Permission not required as long as holding tank is not visible externally
£££ CLG estimates £800-£2650 depending on whether for flats or house n/a 20. Water butt for rainwater collection
Permission not required £ £30
n/a Low
21. Permeable Paving
Permission not required. ££ Can be 2-3 times the cost of
conventional paving.
Measure Conservation considerations and permissions Typical cost (per unit or as specified) Building regs. application needed? Carbon cost-effectiveness Disruption Risks 22. Planting in raised beds in garden
Permission not required. n/a Low Low
23. Composter
Permission not required. £ £20
n/a Low Low
24. Space for waste and recycling storage
Permission not required. n/a n/a None Low
25. Bird box
Permission not required. Encouraged in discreet locations preferably to rear.
£ n/a Low Low
26. Bat box Permission not required. Encouraged in discreet locations preferably to rear.
Further information and signposts
Roof insulation
Installing roof insulation in existing roof voids can have a significant positive impact on energy efficiency. Historic buildings with a timber roof structure lend themselves to insulation
between joists and rafters without any visual impact or harm to the historic building. Natural insulation materials such as wool are particularly beneficial as these allow a building to breathe, reducing the possibility of moisture and damp problems. When fitting, an air gap must be left around the margins of the building to allow air to circulate. Whilst insulation of a loft is straightforward (sometimes referred to as ‘cold roof’), insulation at rafter level (where a loft space has already been converted to provide additional space, or ‘warm roof’) is more complicated. Generally in Westminster there will be no problem with this as long as it doesn’t alter the roof height as seen from the exterior.
For more information and detailed guidance on this see the general information and specific guidance notes on the English Heritage Climate Change and your Homes website:
http://www.climatechangeandyourhome.org.uk/live/insulating_roofs_generic.aspx
Floor insulation
Timber floors can be lifted and insulation inserted underneath, supported by netting. Care needs to be taken when lifting boards to minimise damage. If there is access from below via a crawlspace or cellar, then floor insulation is much easier to achieve. Gaps between floor and skirting, and between floorboards, can be easily filled with sealant (around £20) to reduce draughts, but avoid blocking airbricks when draughtproofing or when insulating, and take care to maintain cross ventilation beneath suspended timber floors to avoid rotting floor timbers. Consider the potential loss of historic fabric (floorboards/skirting/door surrounds/ doors) that may occur if insulation increases floor height. Fitting floor insulation could save you around £50 per year and sealing draughts around skirting boards and floors could save £15 per year.
For further information, see the English Heritage climate change and your home portal: http://www.climatechangeandyourhome.org.uk/live/insulating_timber_ground%20floors.aspx
Solid wall insulation
Solid wall insulation can be a way of improving the thermal efficiency of a building, and could save energy and heating bills. Most of the historic buildings in Westminster have solid
masonry walls, either of brick or stone. Masonry walls are not good insulators and they often feel cold to the touch because they conduct heat. The only way to insulate them is by adding a layer of insulation either internally or externally. Modelling undertaken for Westminster5
shows that there is a marginally better performance with external solid wall insulation but it is also better for a number of other reasons – the cost is generally lower, there is no loss of habitable area, no disruption to occupants – the premises need not be vacated, and less condensation problems than with internal wall insulation.
External insulation
Walls can be difficult to insulate effectively because of compatibility and potential damp problems. Solid masonry walls are intended to ‘breathe’; exchanging moisture readily
keeping problems of damp at bay. When a non-permeable membrane is added that prevents moisture from evaporating problems of damp and rot can occur, so this must be undertaken carefully. The other major issue to consider is that external wall insulation will have an impact visually on the relationship between the building envelope and its openings, altering the detailing around windows and doors, and also eaves and roof verges. For this reason in conservation areas it is only likely to be allowed on the rear elevation, and only in an enclosed situation, not part of a unified terrace, where it does not cover up brickwork (so replaces/ upgrades existing render); and the thickness and visual impact mean that details of the windows are maintained.
For these reasons any external insulation has to be individually designed for each building and carefully installed to address these potential problems. For conservation areas and listed buildings, it may not be acceptable and advice should be sought from a design and
conservation officer.
For further information see the factsheet produced by English Heritage: http://www.climatechangeandyourhome.org.uk/live/insulating_solid_walls.aspx
Internal insulation
This will involve attaching insulating plaster-board laminates or wooden battens with insulation attached to the inside of the wall. It is disruptive and will require a property to be empty, and probably kitchens and bathrooms to be completely refitted. Both forms can result in energy savings, but do take up internal floorspace and alter the relationship of the door and window reveals, and will require skirting boards, cornicing and decorative plasterwork to be relocated. Again there are inherent risks in creating thermal bridges for moisture which can result in damp and rot problems in localised areas, so an air gap is recommended. It is also more expensive than external insulation, and the additional costs associated with having to vacate a property and completely refit kitchens and bathrooms adds significantly to the overall cost, unless such works are programmed when a whole house refurbishment is planned. In some situations, such as listed buildings where there is little remaining internal historic fabric this may be acceptable, but will require listed building consent. Check with a design and conservation officer.
For further information see the factsheet produced by English Heritage:http://www. climatechangeandyourhome.org.uk/live/insulating_solid_walls.aspx
Windows
Refurbishment, secondary glazing and double glazing.
Much heat is lost through windows, both the glass and the gaps in and around the frames. For opening windows you can buy foam strips (the cheapest and simplest option, although these don’t last long and are not recommended for sash windows), or metal or plastic strips with brushes attached, which are longer lasting. Sash windows will probably require
professional refurbishment or use a brush strip. The refurbishment of existing windows can improve their thermal performance and their ability to retain heat, so too can secondary glazing which is now available in a variety of systems to suit different styles of window opening (sash, casement etc.) and with a thin profile. Combining both of these together will increase the positive effect. The heritage conservation value of the building will influence the options that are available, as alterations to windows can have a significant impact on the historic value of the building or area. The typical cost to refurbish and draught-seal an existing sash window is around £200-250. Specialist advice may be necessary to deal with ventilation and condensation and measures which reduce ventilation may not be appropriate in kitchens and bathrooms.
Double glazing, (which will have the best thermal performance), may be acceptable where the replacement frames will match the dimensions, profile and material of the original. English Heritage have recently completed a study into the thermal performance of sash windows. The results indicate that even the simplest repairs and basic improvements will significantly reduce draughts and heat loss, and that using a combination of these methods will upgrade a window to meet the targets in the building regulations.
In particular they found that:
• Simple repairs to mend cracks and eliminate gaps can significantly reduce draughts. On the window that was tested air infiltration was reduced by one third.
• Air infiltration through a sash window in good condition can be reduced by as much as 86% by adding draught proofing.
• Heat loss through contact with the glass and frames can be significantly reduced by adopting simple measures like closing thick curtains and plain roller blinds. In the test heat loss was reduced by 41% and 38% respectively
Chimney damper or balloon
Open fireplaces can lead to draughts and heat loss. Dampers can be closed in winter to minimise draughts and heat loss, and opened in summer allowing flues to be ventilated, and assisting in cooling. Alternatively a removable chimney balloon can be inserted, when the fireplace is not in use. This is considered a better solution than closing off and capping a chimney, which might increase moisture levels in the building fabric.
Installing an energy efficient/ low NOx boiler
Gas boilers are responsible for around 60% of the CO2 emissions of a gas heated home.
Modern condensing boilers are much more energy efficient than older combi-boilers and should be upgraded to a condensing boiler whenever the opportunity arises. Boilers with low emissions of NOx are recommended in Westminster, as there is an air quality problem across the borough for nitrogen dioxide (NO2), which arises in part due to the combustion of gas
Heat pumps
These take warmth from the air or ground to supply heating or hot water to a building. They require electricity to run so are not strictly renewable, but are a low carbon energy source, as they are more efficient (producing typically up to 4 units of heat for every unit of electricity. A conventional boiler produces around 0.8-0.9 units of heat from a unit of electricity. These are best suited to buildings that are fairly air-tight, with good insulation levels, as they produce less heat than a conventional boiler. They will result in radiators which become warm rather than hot, and so are often best suited to buildings with underfloor heating. When used to heat water a backup system may be required to provide top up heat. Air source heat pumps can be noisy, which means they will not be suitable in all instances. They are often reversible (and can therefore act as a form of cooling in summer).
PV electric solar panels
The orientation of the roof is critical for maximum operational efficiency of solar PV panels. These should be as close to south facing as possible, and work best at an angle of 30˚. They should not be shaded by trees or neighbouring buildings. These offer a payback period of around 6-16 years, and since the feed in tariff was introduced in April 2010, these may offer the chance to generate income through selling excess electricity back to the national grid. Under this scheme energy suppliers make regular payments to householders and
communities who generate their own electricity from renewable or low carbon sources such as solar PV panels. The scheme guarantees a minimum payment for all electricity generated by the system, as well as a separate payment for the electricity exported to the grid. These payments are in addition to the bill savings made by using the electricity generated on-site. For more information see: http://www.energysavingtrust.org.uk/Generate-your-own-energy/ Sell-your-own-energy/Feed-in-Tariff-Clean-Energy-Cashback-scheme
The installation of PV panels can also significantly reduce CO2 emissions. Many historic
properties will be able to fit these panels, especially where they can’t be seen from the street. Behind parapet walls, on rear roof slopes which are not visible from the street are ideal. An alternative to conventional solar PV panels are solar roof tiles, which work in the same way, but are designed to look almost identical to normal slate roofing tiles, although these may be less energy efficient than normal PV panels.
Hot water solar thermal panels
Solar thermal collectors are used to capture and store heat from the sun to provide hot water (up to 60 c) in insulated tanks. It is most likely to be used to top up or supplement a main system, rather than provide all of a buildings water heating demand. It is most suitable for buildings which have a sufficient demand for hot water, such as domestic use. It can also be used for cooling, by linking to a cooling system, although this requires heat of a higher
temperature. For optimal efficiency they should be positioned at a 30˚angle as close to south facing as possible. Other orientations will provide a lower yield. They may be suitable where hidden by a parapet wall, or on the rear roof slope of a building. In addition to the collector panels, space is needed to house a large hot-water cylinder with a storage capacity of at least 120 litres, and up to 200-300 litres for larger buildings. Additional pipework will also be necessary.
Micro Combined Heat and Power (Micro CHP)
This is a relatively new technology which is still being trialled, but has good potential to replace domestic gas boilers. A Micro CHP system produces electricity at point of use, and makes use of the heat produced as a by-product, which would ordinarily be wasted. Because it doesn’t require distribution it is highly efficient. It is best suited to uses which have a high and fairly consistent demand for heat.
For further information see Combined Heat and Power Association: http://www.chpa.co.uk/
Living roofs and walls
Technologies have evolved to enable planted roofs and to support the growth of plants up walls, ensuring they have a medium to grow in and the necessary support system. A well designed living wall, like a living roof, will make a significant contribution to conserve and enhance biodiversity, creating green corridors. They can also reduce buildings overheating (and reduce the urban heat island effect), reduce CO2 emissions, absorb noise and trap air
pollutants. The cost of a living roof is estimated at £85/m2 including waterproof membrane
with root bar 120mm, extruded polystyrene with separator layer, drainage board with filter and substrate of 120mm plus wildflowers.
For further information see the environment agency green roof toolkit http://www.environment-agency.gov.uk/business/sectors/91967.aspx and http://www.livingroofs.org/
Water efficient fixtures and fittings
Research shows that water efficiency measures have a lower carbon cost and should be prioritised ahead of measures which substitute the source of water such as rainwater or greywater recycling systems. Cheaper and less energy-intensive ways of saving water include low-flush toilets, low flow taps, low flow showers and waterless urinals. The evidence
suggests that these options should be pursued before water recycling options. Additionally, behaviour change programmes have significant potential in helping us adapt to climate change and can be linked with saving energy, reducing waste and sustainable transport.
Water meter
Consider fitting a water meter to cut the cost of your annual bill, which will otherwise be based on the rateable value of your home. In general if you have more bedrooms in your house than people you could reduce your bill and save water.
Bird and bat boxes
Although there are a number of lower price options available in wood, these tend to rot within a few years. Better options include those made of woodcrete, which are smart and durable. They are also available for a variety of purposes – nursing, nesting, hibernation. Bird box options are also available by species.
Further information
Contact 020 7641 2531 or see the planning permissions section of the council’s website at www.westminster.gov.uk/services/environment/planning/permission for information on
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