The Diocese aims to make its own building developments sustainable and low carbon.
For this ambition to be realised, detailed advice and resources are needed to draw on, with examples of best practice, for architects and Quinquennial Inspectors to draw on, as well as other construction professionals working for parishes and churches.
New parsonage houses have taken a strong lead in the diocese, and nationwide, in achieving Code 6 under the Code for Sustainable Homes, when this was applicable. This means they were adjudged ‘fully sustainable’, and effectively net zero carbon.
Code 6 sustainable parsonages have included those at:
- St John Wembley
- St Nicholas Perivale.
St John Wembley parsonage house
The first fully sustainable diocesan development was the Parsonage House completed in 2011 for St John’s Church in Wembley, designed and built to ‘Code 6’ under the Code for Sustainable Homes. The Project Surveyors were Wilson Stephen Associates, now Edwards Wilson.
This effectively zero-carbon house features:
- Super-insulated walls, windows and roof
- A south facing photovoltaic roof
- Heating and hot water from a ground-source heat pump
- Energy and water-saving fittings and appliances
- Environmentally-friendly materials
- Minimum construction waste
- On-site recycling and composting
- Rainwater harvesting.
St John’s Vicarage was awarded the highest ever score awarded under the Code (at that time and for some years after), at the 2012 Awards by BREEAM (BRE Environmental Assessment Method).
St John’s Church hall
St John’s Vicarage formed part of a development in partnership with ASRA Housing Group. It also includes a new community hall, which achieved BREEAM Excellent standard. The building features:
- Low U value (high insulation) roof, walls and floor including windows and doors
- Low permeability
- Photovoltaic roof
- Low energy lighting
- High efficiency gas-fired boiler
- Mechanical ventilation and cooling
- Reduced flow taps to wash hand basins
- Rainwater harvesting.
St Mary of Eton
The redevelopment of the site of this church, designed by Matthew Lloyd Architects, included refurbishing the church, and the provision of new community facilities and housing.
The development received a much coveted award from the Royal Institute of British Architects (RIBA).
Regrettably, the government has withdrawn the Code for Sustainable Homes.
New parsonages, to St Mary Willesden and elsewhere, are now aiming for Passivhaus standard.
St Paul’s Hammersmith
Another pioneer in sustainable construction is the new Church Centre at St Paul’s Hammersmith by Richard Griffiths Architects. The building features:
- Deep bore ground source heat pump system in the form of energy piles
- Sedum roof
- Three storey atrium providing daylight to the basement
- High thermal performance of building envelope.
This development also won an RIBA award.
Jesus Church Forty Hill
Another church hall development, noted for its sustainability, is the Charis Centre at Jesus Church Forty Hill, designed by Neil Jennings Architect. This building features a heavy wall construction to reduce overheating, a heat pump, and natural daylight penetration into the building as well as natural ventilation and low energy lighting.
This modern C of E secondary school completed in 2010 for the London Diocesan Board of Schools and the Royal Borough of Kensington & Chelsea achieved BREEAM Very Good with:
- Ground source heat pump and heat exchange units
- Planted roof areas.
Construction and design principles
Churches buildings should reflect our values. They are both historic and social, as well as spiritual places. Any building project to a church or associated building should reflect the commitment of churches to God’s creation and to our fellow human beings. Whether for new-build, extensions or alterations, or retrofitting projects; whether for churches themselves or other church property; net zero carbon is the gold standard to aim for.
Other considerations include:
- Passive versus active design
- Thermal and moisture behaviour and performance
- Air tightness versus provision for ventilation and breathability
- Natural insulation
- Porous paving
- Living walls and green roofs
- Rainwater harvesting
- Use of ecologically sound products from sustainable sources
- Sustainable construction practices, conserving site resources.
Typical rules of thumb for planning purposes include:
- Reducing waste by 50%, reusing a minimum of 10%
- Minimum 10% renewable energy.
However the Diocese together with the whole Church of England now aims for net zero carbon by 2030. Therefore the above minimum standard for renewables will normally need to be exceeded, with purchased electricity from an approved 100% renewable supplier, and any gas either 100% biomemethane or else offset by other robust and valid means.
We should integrate the building’s setting with the natural environment. As far as possible, internal spaces should connect with the external environment and external spaces should accommodate and welcome the natural world.
Designers should plan for energy, carbon, waste and water reduction throughout the lifetime of a building, not just the construction process. This includes sourcing materials, to recycling those present; from the building’s ecological impact to how its constituents can be recycled at the end of its life.
Historic churches have lasted for many generations; how can we prepare them against climate scenarios for 2050 and beyond, and thus improve their chances of survival into the future?
Whilst efforts continue to limit temperature rises, it is necessary to plan for global average temperatures of 2 – 4 degrees C within the 21st c. Temperature rises on land tend to be double the average, those at sea somewhat less.
Therefore temperatures of 35-38 degrees C may become normal for UK summers within the lifetimes of buildings being constructed today, with occasional heat waves of 40 degrees or more. How can we design buildings and interiors that will remain tolerable under such conditions?
Social sustainability is important as well as environmental sustainability – and they support each other.
Any church project is a community project, therefore. The local community should be involved from the beginning and kept engaged:
- Responsibility for building targets should be clearly identified and communicated throughout the construction process and thereafter, to all stakeholders;
- This extends to the construction crew, as well as to future users;
- Employing contractors who subscribe to the Considerate Constructors scheme.
Accessibility is a well known and essential objective.
How can we go beyond the accessible WC to make sure there is no impediment to a building’s use?
Let’s think through disability to the principles and their wider application; what other issue might also be preventing the wider community utilising this space?
The flexible use of a new building for years to come can be ensured by building in the potential for multi-use and subdivision from the outset. The better all its users are accommodated and welcomed, the more a building will be appreciated and cherished into the future. It might become a haven in troubled times.
New buildings are likely to be designed to remain standing till at least 2050 and beyond, and should therefore attain the standards which are expected to be required at that horizon.
Compliance with building regulations at the date of construction may be the legal minimum, but is not a sufficient response to the impending climate and sustainability crisis.
Conservative materials and construction techniques as seen in the best historic buildings may represent a superior paradigm to modern materials and constructions.
On the other hand, new techniques developed more recently in response to environmental and particularly climate challenges, such as green roofs and the use of structural timber are to be encouraged.
Alterations and retrofitting
Alterations to existing buildings should achieve standards applicable to the end of their design life, that is the lifetime of the new interior fittings or retrofitting measures.
The shell of a building will likely last for longer than its interior, with multiple interior refits or reorderings. But interior fittings will tend not to be renewed during the last years of a building’s life.
Therefore as a rule of thumb, the design lifetime should be the same as the expected life of the building shell, unless that is more than double the expected life of the fittings – in which case a further refit with the opportunity for additional upgrade would be viable when the time comes.
Brickwork and ceramics
Brickwork and ceramics are traditional and durable materials, the source material clay being readily available and inherently without significant environmental impacts. The process of kiln firing consumes fossil fuel energy and generates carbon emissions.
Natural stone and slate
Stone is a natural material, worked manually without applied energy. Importation costs dear in terms of energy and emissions.
Primary supplies of some UK stones are close to being exhausted. Once a quarry or seam has been worked out, material is renewable only by recycling, having been created in the first place by geological processes of extremely long duration.
Therefore old material should be reclaimed wherever possible. Bear in mind the vulnerability to extreme weather, especially of sandstone and soft limestones.
Slate remains available from UK quarries in Cornwall (Delabole), Wales and Cumbria (Westmoreland) – although availability is diminishing.
Cement and concrete
Portland cement for mortar or concrete contributes to greenhouse gas emissions which add to global warming (60% comes from the calcium carbonate in limestone, 40% from energy used to heat the kiln, though alternative energy sources to fossil fuels are increasingly available).
It can be argued that use of concrete in construction should be restricted to circumstances where an appropriate and economically viable alternative cannot be found; that the versatility, ubiquity and even the reliability of the material are not sufficient grounds for continuing to employ concrete as a primary load-bearing material.
Part of the reason why concrete accounts for such a high proportion of world emissions is its dominance in the construction industries of so many regions. If displaced by structural timber and brick, it might be argued, emissions from those sources would rise, so the saving would be less.
Steel reinforcement and disposable plywood shuttering also need to be accounted for in the carbon cost of reinforced concrete – tending to tip the balance of the argument against.
Limecrete should generate less emissions than concrete, because less energy is used in producing lime than cement.
The use of wet and dry mortar mixes with lime instead of Portland cement is also to be encouraged.
Lime is also a constituent in a range of other traditional new sustainable applications such as plasters, floor components and screeds, limewashes and lime hemp.
Worldwide, supplies of sand grades suitable for building are becoming severely stretched, though for now they remain readily available to the UK construction industry: another reason for using lime.
Extraction of sand for importing from the developing world may cause serious damage to river beds for example.
Timber should be sourced only from forests approved by the FSC (Forestry Stewardship Council). Subject to that guarantee of the sustainability and non-threatened status of the species and population, timber is inherently a renewable material.
There is no shortage of softwood of structural grades for construction. There is little intrinsic reason why naturally grown timber should not be used in any construction.
It is essential that it should in fact be renewed, generally in the same species, and that the felling and planting of trees in relation to their numbers and growth cycles are managed in such a way that thermal balance and the uptake of carbon dioxide are maintained.
A high proportion of tropical hardwoods are now threatened species and not to be used, both from a conservation and land-use point of view.
UK-sourced timber is to be encouraged. This may be more expensive than imported wood, but the difference may be offset partly by the reduction in transport costs and emissions. It is generally managed sustainably, and an increase in coverage due to demand for construction has less effect on temperatures than nearer the pole or the equator.
The use of large laminated carcassing panels for high rise blocks is intriguing, but glue laminated timber does not emerge specially well as a sustainable material. Doubt has recently been cast on the use of any timber in tall buildings, following the Grenfell Tower disaster. That was due to materials and systems quite other than timber, but timber cladding for example is nonetheless likely to be combustible.
Timber is sometimes used because it is sustainable, but inappropriately in a manner that is unsustainable – e.g. natural unpainted timber used as a decorative external material. In the UK climate, this can become very shabby in just a few years. Very careful and realistic consideration of impregnation and/or durable protective films is needed by the architect.
Metallurgy especially aluminium manufacture contributes to worldwide carbon emissions, although the proportion of worldwide emissions is reducing.
This can be further mitigated by recycling – but claims for a carbon-negative potential for example through use in solar panels should be viewed with scepticism.
However alternatives such as uPVC in double glazing are fraught with at least equal issues.
Glass and glazing
Silicates which are the primary raw material for glass are among the most abundant materials on earth.
The heat intensive manufacturing process does require fuel use and therefore carbon emissions, but no satisfactory alternative exists other than plastics.
Glazing frames are a choice between timber, aluminium or uPVC. Purpose made timber double glazed windows are becoming more common and viable.
The thermal performance of double or triple glazed windows is rated A to G by the Glass and Glazing Federation (GGF).
Plastics are a petroleum by-product. While some recyclable products exist, most hard plastic materials such as uPVC are uneconomic and/or unfeasible to recycle.
Plastics generally can be very environmentally destructive especially when discharged into marine environments, where the horrible consequences have become infamous. Their use should be avoided whenever a viable substitute is available.
Careful consideration and rigorous control upon the manner and destination of plastics to be disposed of is essential.
Insulating standards expressed as U value are becoming more stringent in building regulations.
A range of recycled insulating materials e.g. from glass bottles and solid wall insulation systems are becoming available.
For existing traditional buildings, it is important to model the effect on the thermal behaviour of the whole building in all seasons, as well as the implications for moisture transmission and condensation.
Insulation has a limited lifespan which may vary but materials will eventually break down, therefore should be designed for ultimate replacement.
Natural wool insulation is renewable and may even be carbon negative. The use of sheep’s wool has resulted in moth infestation, but at least one company has claimed to have resolved this problem.
A green roof may comprise a flat or low-pitched roof construction, mainly for new buildings and extensions, incorporating planting on a layer of topsoil on a waterproof membrane.
This is frequently described colloquially as a ‘sedum’ roof. Sedum is a genus of low-growing perennial plants with a wide variety of colours and textures.
Green roofs reduce rainwater run-off and mitigate flooding. They can also provide thermal and sound insulation as well as encouraging bird and insect life and therefore local biodiversity.
Planting on green roofs is to an extent self-maintaining, but roof access is still required.
‘Embodied’ energy and carbon
These terms express important concepts although the term ‘embodied’ (or ‘embedded’) can be misunderstood.
Strictly speaking, the phrase ’embodied carbon’ should mean the carbon sequestrated in an organic material (such as timber), withholding it from release into the atmosphere so long as it remains in place. This is to be encouraged.
On the other hand it places constraints on demolition and disposal, which should be organised and managed in a way which retains the carbon content. 100% recycling is to be aimed for, where feasible.
Bricks for example can be cleaned and re-used; there is a substantial architectural salvage trade for this and other building parts.
Waste timber e.g. rotten window frames could be broken up to form a wood pile in a treed area – encouraging biodiversity (stag beetles for example). Aerobic burning in the open is to be firmly avoided.
Process and transport energy and emissions
However, ‘embodied (or embedded) energy and carbon’ are usually taken to mean the energy used and emissions generated in procurement and construction, viz manufacturing and transporting the material to site, then in site works.
Embodied carbon in this sense is out of scope for purposes of the Church’s target of net zero by 2030. Nonetheless the energy and emissions resulting should be considered in planning of any new building or alteration to an existing building. A calculation may also be required for purposes of gaining planning permission, eg in the City of London.
New buildings, alterations and replacements
There is a widespread perception that existing buildings carry with them an ‘embodied’ energy or carbon which is ‘locked into’ the building and will be released should the building be replaced, therefore militating against the replacement of that building (or even any part of it).
This is partly valid and partly not:
- Carbon sequestrated in the fabric of the building should be intelligently and responsibly dealt with on demolition and disposal;
- The process and transport energy and carbon associated with the new building needs to be accounted for;
- But the process and transport energy and carbon when constructing the existing building has already been expended; it is a historical cost and there is no point accounting for it;
- The carbon sequestrated in the new building (true ‘embodied’ carbon) may partially offset the process and transport energy and carbon for that building, after subtracting any part of the carbon unavoidably released from materials in the old building (in the form of CO2e);
- The predicted energy performance and annual carbon footprint of the building in use need to be taken into consideration. To the extent this is better than before (it should be much better), after a period of years which can be estimated, it should pay back the net cost of process and transport carbon less any increase in sequestrated carbon in the new or altered building compared to before.
A similar calculation may be employed in relation to replacing any part of an older building, e.g. the windows or interior fittings.
The energy and carbon costs of demolition need to be accounted for. They should be advised in the handover manual to the client, and subject to a plan by the demolition contractor.
Life-cycle energy and carbon
The total expended through the process of procuring, constructing, using and eventually demolishing a building, may also be termed ‘embodied (or embedded) energy and carbon’.
This can yield paradoxical information. For example, brick has a higher total life-cycle cost in energy and emissions than concrete. After taking the greater density of concrete into consideration, they emerge as much the same in energy and carbon terms.
Timber also appears not to be of a lower order in its energy and carbon cost, but that takes no account of its sequestration value.
Carbon sequestrated in building materials is measured in different units than process and transport energy or emissions:
- Sequestrated carbon (true embodied carbon) – kg or tonnes of carbon (C)
- Process and transport energy – kilowatt-hours (kWh)
- Process and transport emissions – carbon dioxide equivalent (CO2e).
Raw carbon in may be converted into CO2, or other compounds especially CH4 (methane), before or after release into the atmosphere; if burned some of it remains as black carbon (soot).
To convert carbon to CO2e, multiply by 3.67. The conversion factor from kWh to CO2e, which represents carbon intensity, depends on the fuel. Conversion factors for the previous year, for reporting purposes, are standardised by the Church of England for purposes of the Energy Footprint Tool.
Projected figures for future carbon intensity may be obtained from UK Government data.
Water and waste
WRAP (Waste and Resources Action Programme) provide comprehensive advice and information.
Standards and regulations
BREEAM (Building Research Establishment Environmental Assessment Method)
BREEAM describes itself as ‘the world’s leading design and assessment method for sustainable buildings’. The method sometimes yields counter-intuitive results, but it is the most comprehensive assessment procedure for all aspects of sustainability in the round.
The six BREEAM ratings are:
- Very Good
Energy Performance Certificates (EPCs)
Energy Performance Certificates (EPCs) are required when buying, selling, renting or letting premises including residential and commercial property, which may include church halls.
In 2016, regulations came into force requiring rental properties to have an EPC Grade E or better. The requirements were as follows:
- Since 1 April 2018, an EPC Grade E or above has been required for new tenancies (domestic or non-domestic), and also renewals or extensions;
- From 1 April 2020, this requirement was to be extended to existing domestic lettings;
- From 1 April 2023, it has also applied to existing non-domestic lets.
These requirements are set out in the Energy Efficiency (Private Rented Property)(England and Wales) Regulations 2015. These regulations in turn refer back principally to the Energy Performance of Buildings (England and Wales) Regulations 2012, which already laid down requirements for EPCs (and DECs – see below). The 2015 regulations apply where an EPC is required under the 2012 regulations (and/or the previous 2007 version of those regulations), or under the 2010 Building Regulations (see sub-section further down).
Plans for the above requirements to be strengthened from 2025 onwards were cancelled by the Prime Minister in his speech on 20th September 2023.
Where a property falls short of the current requisite standard, works to improve it must be undertaken.
There are currently several exemptions:
- For use as a place of worship or for other ‘religious activities’;
- For non-domestic tenancies of more than 99 years; or less than six months (if non-renewable after that, and if they don’t follow on from previous occupation lasting more than 12 months);
- For a landlord who has recently taken over the property;
- Where the landlord has already made all relevant improvements;
- Where an (existing) tenant withholds consent for the works;
- Where third party consents are not obtainable or conditions are unreasonable. This includes planning or listed building consent where required;
- Where the improvements will result in more than 5% loss in property value;
- For non-domestic properties, where any necessary improvements will not pay back in less than seven years;
- For domestic properties, the requirement to upgrade is subject to a funding arrangement at no cost to the landlord.
The landlord must register all of the above; the regulations set out how.
The foregoing applies to works by landlords; any works by tenants are dealt with by a separate section in the regulations.
The 2015 regulations apply to lettings, not sales. However both sales and lets do still require an EPC under the 2012 regulations – for marketing and advertisement; to be provided free to the prospective buyer, as well as to the lessee for lets; and for display of the EPC if the building to be sold or let is a public building of more than 500 sq metres.
The 2015 regulations are required to be reviewed every five years, viz 2025, 2030 and thereafter.
Display Energy Certificates (DECs)
Display Energy Certificates (DECs) are required for any premises open to members of the public, of which the public parts exceed 1000 sq metres. This applies at any time, not just when the building is sold or let (when the same building will require an EPC as well).
DECs are not required for premises used for ecclesiastical purposes, including churches and church halls.
EPC and DEC purposes
EPCs (see above) and DECs are subtly different. An EPC measures the intrinsic energy performance of the premises, whereas a DEC shows its actual energy efficiency in use, which will depend on how well it is managed.
Results and calculations
EPCs and DECs display figures for the carbon emissions associated with their energy use. Unfortunately these figures cannot be replied upon. In the case of EPCs, the calculations embodied in the software are incoherent, yielding contradictory and incorrect results. DECs use out of date conversion factors. Churches and others are therefore advised to use the Church of England Energy Footprint Tool and Energy Toolkit for reporting energy use and emissions from preceding years.
For predicting future emissions, the government website may be used (see ‘Units’ under ”Embodied’ energy and carbon’, above), or for a simple and robust estimation EPC conversion factors may be used (0.000139 tonnes CO2e per kWh for electricity, 0.000185 T/kWh for grid gas) – even though these parameters are not correctly reflected in the figures printed on EPC certificates.
Building Regulations Part L
Part L of the national Building Regulations concerns the energy efficiency of buildings and building works.
Unlike other sections of the Building Regulations, rightly or wrongly Part L does not cover churches where used ‘primarily or solely as places of worship’, nor historic buildings where their character would be changed unacceptably.
Nevertheless, the provisions of Part L should still be adhered to or exceeded wherever feasible.
Whether designing and building new buildings, alterations or upgrades, it is essential to obtain appropriate design and supervision by an architect or qualified building surveyor. Building services engineers are also likely to be necessary.
Professionals need to be very carefully selected and assessed before appointing them to provide design services, including all necessary specifications and drawings, then site supervision.
Knowledge and experience in relation to sustainability, energy conservation, carbon emissions and other environmental considerations are essential.
For ‘traditional’ buildings, and especially listed buildings, historic building conservation experience and accreditation are also necessary, for example from Architects Accredited in Building Conservation (AABC).
Advice and resources
The Centre for Alternative Technology in Machynlleth, Mid Wales was a pioneer in the field. It demonstrates exemplars of many systems and technologies. CAT’s new WISE building is designed to be highly sustainable. For example it uses rammed earth – inspiring as well as very unusual in the UK.
Other well known exemplars are Bioregional (‘One Planet Living’) and the recently developed LETI Design Guide.
Diocese of London
Before embarking on any project, it is essential to discuss with your Archdeacon.
Diocesan Advisory Committee (DAC)
The DAC (administered by Parish Property Support, link below) takes the environment and sustainability into consideration when considering faculty applications.
The Head of Environment and Sustainability is also the Environmental and Sustainability Consultant to the DAC.
Head of Environment and Sustainability
Parish Property Support Team.
London Diocesan Board for Schools.
Diocesan web pages
Climate Action Projects
Climate Action Finance
Green energy suppliers.
Energy Footprint Tool
Embodied carbon (Church of England guidance).
Climate and environmental risks
Resource depletion and sustainability.
Building Regulations Part L
Exemption for churches in use
Energy Performance Certificates
Energy efficiency and planning law
Energy Efficiency (Private Rented Property)(England and Wales) Regulations 2015
Energy Performance of Buildings (England and Wales) Regulations 2012
Display Energy Certificates.
Standards and accreditation
BREEAM (BRE Environmental Assessment Method)
Centre for Alternative Technology
Architects Accredited in Building Conservation (AABC)
Sustainable Traditional Buildings Alliance
UK Green Building Council
LETI Design Guide
Glass and Glazing Federation (GGF)
Forum for the Future.
WRAP (Waste and Resources Action Programme)
Business and Commercial Waste
Zero Avoidable Waste in Construction.
Professional and commercial
Matthew Lloyd Architects
Resources on the environment
Environment and sustainability, front page.