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Our 'estate'... minimising carbon footprint

This article is one of a number offering expert but general advice about maintenance and repair of property in our area.

'minimise our carbon footprint'
has kindly been contributed by
Roger Mortimer


Also see...

Stone Garden Walls  Common Property Issues No.1
Trees 
Common property issues No.3
Ironwork 
Common Property Issues No.4


Minimising our carbon footprint

Click on headings on list of contents or scroll down the page

Introduction

It may seem that the small contribution that a house can make is pointless.

However houses contribute 24% of UK carbon emissions, and as existing homes will continue to account for about 90% of the total housing stock in the UK reducing the carbon footprint of these is very important.

More significant than making the small number of new dwellings carbon neutral. Some 'green' improvements will also reduce running costs, achieving the same or better comfort while using less energy. Low running costs are becoming a factor in house valuations, underlined by HIP Energy Certificates. . So there are financial as well as green virtues in the suggestions made. In some cases Government grants are available.
(See Low Carbon Buildings Programme.)

Domestic energy consumption is heavily influenced by the way we live.

This is not RCAS territory! - so we deal only with the home and its equipment. The bricks and mortar – and not the 'typical' two storey suburban semi upon which most green advice seems to be based but that more typical of our area. Solid, stone built, usually 3 storey, detached, semi or terrace houses. Some suggestions do not apply to flats, or may not be possible due to leases and legal arrangements.

Major building alteration and repair operations, for example re-roofing and extending, provide an excellent opportunity to incorporate energy saving and energy generating measures that go beyond those mentioned here. However all building activities, however well intentioned, consume energy, so it is important to use 'sustainable' materials, with low embodied energy and from renewable sources.

(See National Green Specification)

There is much general advice available to those seeking to make their homes more sustainable

but professional help may be required.
(See The Green Register for some specialists and Greenstreet for some examples of eco-refubishment).



Steps to a lower carbon footprint

Reduction of energy demand by
  • Structural measures – eg good insulation, draught and weather-stripping
  • With energy efficient heating equipment and controls, and other services
  • By making renewable energy oneself – eg, using Solar energy for water heating and micro-generation of electricity

Structural measures

Roofs
Typically slate, clay or concrete tiles on felt and timber rafters. Major source of heat loss, well worth dealing with.
Aim for 300mm of insulation in roof space if practical.
(Adding insulation to existing buildings can cause condensation if not correctly specified –
if in doubt seek expert advice.)


Roof lights
e.g. existing 'original' skylights, typically over stairs.
Replace with timber double glazed units, openable for summer ventilation.

Dormer windows
Often lightly constructed un-insulated structures and adjoining roof slopes.
Consider stripping down and installing insulation.

External walls

Typically solid, thick, usually brick or rubble stone inside faced with dressed stone externally, with render to side and rear walls. Provide a good heat store, slow to react to temperature change, but exposed north and east facing walls can become very cold particularly when the render is saturated.

 If doing a major building upgrade worth considering adding external insulation and re-rendering.
Internal insulation is a less satisfactory solution, as it does not use the benefits of the wall’s thermal mass.

Floors
Concrete floors to ground floors and basements. Difficult to add insulation, unless installing new raised floor, eg, strip flooring, when insulation can be incorporated in some cases.

Suspended timber floors, with ventilated airspace under are a considerable source of heat loss, difficult to deal with unless doing major works.
See draughts below.

Draughts

Major source of heat loss and discomfort. Review all external openings, even letter boxes and loft hatches.

Create draught lobbies if possible, and draught proof external doors and doors to unheated spaces.

Ventilated floor spaces can cause considerable drafts if the floorboards are not closely laid – it is possible to have wide gaps filled as part of a renovation and still have the floorboards left exposed.

Alternatively, carpets with underlay on hardboard sheeting will also cut out drafts.
(Requirements for natural ventilation for gas appliances must be considered when closing draughty openings –
if in doubt seek expert advice.)


Windows 
Timber double hung sash windows are typical. Their relatively modest size in relation to solid wall makes heat loss through them less important than often assumed.

Badly fitting timber windows leak heat and cause draughts.
First step - have these overhauled by specialist, who can fully weatherstrip against draughts and noise, and make to easy to operate.

It is usually unnecessary to renew the whole window.
(Plastic replacement windows never look right and UPVC is now regarded as unsustainable.)

Other measures -


Double glazing
Difficult to install particularly if the windows have slender traditional glazing bars, as the thicker glass needs heavier and often obtrusive glazing bars.

Secondary glazing
demountable 'winter' glazing in clear acrylic, which can be taken down and stored may be good alternative.
Or clear plastic film adhered to the window frame - this needs to be used where the thin film will not be damaged, for example for fixed high level glazing, perhaps the stained glass panels so common in our area.

Shutters
Many houses were built with folding timber shutters to main windows.
Very effective protection against cold radiation . Use if available and consider reinstating if missing.

Consider also insulating roller blinds and thermally lined curtains


Energy efficient heating and services

Internally -

Heating

Most commonly gas boiler and radiators. Now established that modern combination boilers, with zoning, time clocks and thermostatic radiator valves make energy savings that usually justify replacing older systems. 

Lighting
Use low energy light bulbs or other low consumption sources such as fluorescent tubes. Tungsten 'strip' and spot lights, together with multiple Low Voltage and Halogen lights are energy intensive. 

Power
Consider replacing older appliances such as washing machines, fridges with A+ or A rated ones. It is instructive to survey the power consumption all appliances, including those on stand-by.  
 

Water consumption
Supplying clean mains water and disposing of waste water to the public drainage system are energy intensive processes, so reducing water consumption is important. Action - fit all WC's with dual flushing. Most cisterns can be simply retro-fitted to provide choice of flush, typically 2.5 or 3 litres for light flush and 4 or 6 litres for full flush. Use of these flushing systems can reduce consumption by 20%. Metering provides financial benefit for those who reduce consumption.

Externally -

Sustainable drainage
Do not increase the hard, impermeable paved surfaces which add to the discharge of water to public sewers and increase risk of flash flooding.  Any new hard surfaces to be porous.
(See RCAS Trees book)

Rainwater
Collect rainwater in water butt and reuse.

Gardens
Retain and manage existing trees and plant new trees Trees absorb CO2 and pollutants, and assist in cooling streets - important in view of predicted rise in summer temperatures. Compost all possible kitchen and garden waste.

Food production
Consider growing more vegetables, fruit and herbs.
(See article in this Newsletter on 'Edible Gardens'  by Angela Raffle.)
Even small gardens can grow some 'local produce'. Fruit trees take up relatively little space and flourish in city gardens and  many garden walls suit espalier trees. Little used paved space can be easily converted to vegetable growing by building raised beds on top, perhaps using reclaimed timber to create the raised sides. Gardening books are full of advice on raised bed cultivation.


Renewable Energy

Having done as much as possible to reduce the energy demand of the property, consider renewable energy.
Solar Water Heating and Photo Voltaic (PV) micro-generation are currently the most practical for our area.

The location, orientation, shape and construction of each property will determine what is possible.
The continued rapid increase in all fuel costs is making all domestic renewable energy installations more cost effective.

Solar Water heating

is generally first option. This is usually designed to provide 'free' hot water amounting to 50-60% of annual requirement. A roof slope facing more or less south is required for the panel, plus a dual coil hot water storage cylinder of good capacity. This is pre-heated by hot water from the solar panel.

Solar water systems are currently often more cost effective than PV.

Photo Voltaic panels
also require to face the sun, usually via a south facing roof slope. The power generated is fed into the house electrical supply, reducing meter readings pro rata. The electricity supplier is a key player, and various contracts are available to recognise the contribution of the micro generation.

Currently the Government Feed in Tariff’s make PV generation a very sound investment.

Appearance
Many people are concerned at the visual impact that solar panels may have on their property and the attractiveness of our area. In practice it is sometimes possible to locate panels where they are virtually invisible. A significant number of houses have valley gutters, and 'hidden' roof slopes. Panels on side and rear roofs will also have little impact. Due south is the most efficient aspect, but south east and south west are feasible. Panels can also be laid almost horizontal on flat roofs, though shadowing by other buildings, chimneys and trees should be avoided.

In fact, our roofs have been subject to many changes over the last 50 years. Original natural slates have been replaced with tiles, often concrete ones. Many, often over large, rooflights and dormers have been added. Chimneys have been removed or decorated with aerials. Overall these changes cannot be said to have improved the appearance of our area.

Solar panels can often be no more obtrusive than Velux rooflights. And at least they demonstrate the owner’s commitment to reducing their carbon footprint - a green badge of honour as we move into a very changed environment?

Above, a terrace with solar panels ‘added’ to south facing hidden roof slopes


Solar panels and planning consent for residential property

Update of RCAS advice on need for consent - September 2010

General rule
Solar panels and associated equipment should not project above the roof ridge, or more than 200mm (8") from a roof or wall surface. Provided you meet this rule planning consent is not required if you live in a house.

It is required if you live in a flat, even if this is in a converted house!
There are no extra requirements for Conservation Areas, so this rule covers the whole RCAS area.
Planning consent is required If you live in a Listed Building.

Any queries, phone
Planning on 0117 922 3000

Having to make a Planning Application does not imply that there will be difficulties.
You are also recommended to explain your intentions to neighbours who may be affected by the installation


Further Information

Energy Saving Trust  
www.energysavingtrust.org.uk/ 
Suggested first stop - easy to use and comprehensive information on all aspects

Create Centre 
www.bristol.gov.uk/create 
Visit their Ecohome, with Solar Water heating installed and much other information

Low Carbon Buildings Programme Phase 1 
www.lowcarbonbuildingsphase1.org.uk/
 
for available grants

Green Register
www.greenregister.org.uk

for professional advice

Greenstreet
 
www.greenstreet.org.uk
worked examples of eco-refurb    

RegenSW
www.regensw.co.uk
for Renewable Energy Suppliers

National Green Specification
www.greenspec.co.uk/

Sustainable Redland
http://groups.yahoo.com/group/susredland/

our local group, founders of the Whiteladies Farmers Market and supporters of individual and local group action for a sustainable future