“Peterborough...building the UK's Environment Capital that is our goal and
the design of our new homes and communities will play a major part in
achieving it. Therefore the design, construction and the levels of future
energy and water usage by the residents is key to making a sustainable
community”
Hugh Cripps Chief Executive – Peterborough Environment City Trust
“Peterborough has ambitious targets for growth including the provision of at
least 25,000 additional homes by 2021. As a city we are also on a journey
from Environment City to becoming the UK’s Environment Capital. The
quality of new housing developments in terms of design and environmental
impact is crucial if we are to achieve substantial and sustainable growth.
This section of the Residential Design Guide aims to assist architects,
developers and agents in achieving high quality homes with low environmental
impact.”
Trevor Gibson,
Director of Environment and Community Services – Peterborough City
8.1 Optimum Use of Site
8.1.1 Orientation
8.1.2 Building Form
8.1.3 Wind Protection
8.1.4 Passive Solar Design
8.2 Structure of Property
8.2.1 Reduction of Heat Loss
8.2.2 Heating of the Property
8.2.3 The Use of Low Carbon Technology
8.3 Energy Efficient Lighting and Appliances
8.4 Micro Renewable Power Generation
8.5 Waste Management
8.6 Water Conservation and Management
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
8.1 Optimum use of site
8.1.1 Orientation
The layout of a new development is a fundamental aspect of its design that
can significantly affect the low energy design potential of the scheme,
including the orientation of the buildings to enable solar energy to be
collected passively and actively with buildings having wide south facing
facades. Benefits derived from a southerly aspect can be negated if the
buildings are overshadowed. This is addressed more fully in Chapter 4.10.
8.1.2 Building Form
Controlling heat loss to reduce long-term fuel consumption and to make the
best use of renewable sources of energy is an important first step in low
energy design. Building form is an important influence in that: terraced
homes and compact square plans reduce exposed surfaces from which heat
is lost (Figure 8.1.2A). Detached homes and bungalows are least energy
efficient; narrow-fronted dwellings are more suited to a super-insulation
approach; and wide frontage plans allow greater areas of south-facing
elevations, which are suited to a passive solar approach (Figure 8.1.2B).
8.1.3 Wind Protection
The design of spaces by buildings and planting can contribute to providing
sheltered microclimates in external areas by decreasing wind speeds and
reducing heat losses from buildings due to exposure from wind. Designs
should take into account the: location and form of buildings to avoid wind
tunnelling and wind turbulence; and introduction of tree shelterbelts where
necessary to reduce wind speed around new developments (Figure 8.1.3).
Care must be taken to ensure that the right species are selected and that
planting does not shade solar collecting areas as it matures.
----------------------------------------------------------------------------------- back to top >>
8.1.4 Passive Solar Design
Passive solar design exploits the potential for solar radiation to contribute to
heating needs in homes by providing the largest glazed area on south-facing
elevations to optimise solar gains and use wind for natural ventilation. Best
practice includes:
- orientate windows and living spaces to benefit from passive solar
gains; - use passive stack ventilation;
- introduce unheated conservatory or winter garden spaces on
the south face of buildings to act as a buffer, to capture and store solar
radiation and to pre-heat ventilation air into homes.
should not be compromised:
- large expanses of glazing to private gardens may require special glass
for security; - large windows facing south and overlooking a public area may also
compromise privacy and noise insulation, unless screened.
However, care should be taken to avoid shading i.e. no obstruction to
the south within an altitude angle of 130, although this may not be
possible in denser developments; - if large windows face south-west, they may be
vulnerable to
overheating in summer, as afternoon sun will be lower in the sky than
the sun at midday. Consideration should be given to the provision of
shading devices and ventilation to these spaces, such as brisesoleil
and roof overhangs to moderate unwanted solar gains; - conservatories or atria should
be capable of being closed off from the
rest of the home to avoid unwanted heat losses. The temptation to
provide heating for conservatory and winter garden spaces should be
resisted for the same reason; and where solar gains are used for
background warmth in spaces, responsive heating systems should be
fitted, controlled by temperature thermostats within the room. Where
an unresponsive heating system is used, such as electric storage
heaters, the space can rapidly overheat. The benefits of solar gains
can then be lost if windows are opened to cool the room temperature.
designing for solar gain. Excess heat from solar gains taken in during the day
can be stored in dense walls and floors and slowly given up at cooler times or
at night - the thermal flywheel effect. Insulation should also be provided to
retain as much of the sun’s heat as possible.
----------------------------------------------------------------------------------- back to top >>
8.2 Structure of property
Building control has been use to increase the thermal efficiency of buildings.
The council encourages design that exceeds this regulatory standard
working towards the aim of carbon neutral homes. Whilst the gains that can
be made via solar gain are constrained by the site, design, material choices
and workmanship will substantially minimise the carbon footprint of the
property.
8.2.1 Reduction of heat lost
The building of an air tight building envelop with managed ventilation is key in
working towards the carbon neutral home. This is achieved by:
- Building in an economic shape and design out of cold bridges.
- Consideration of modern sustainable building techniques and
materials is encouraged e.g. prefabrication if elements, modern wood
frames, modern manufactured wood, insulation using biological
material such as sheep's wool or straw bales. - Super insulation of the building envelope e.g. roof insulation in excess
of 300mm rock mineral wool equivalent, the use of insulated plaster
board to dry line the property, insulation of floors. All water pipe runs
should be insulated as well. - Ventilation of the property should be managed to achieve best
practice of 3 m3/h/m2 air exchange or good practice of 5 m3/h/m2.
This is likely to be achieved using passive stack ventilation or
mechanical extract ventilation. - Windows sited for maximum solar gain and of high energy efficiency.
Wood or metal frames would be preferred. - Airtight construction requiring good detailing and air pressure test
determine the quality of the build.
8.2.2 Heating of the property
- The main heating system should aim to exceed the current Central
Heating System Specification (CHeSS). Central heating boilers should
be SEDBUK A rated. The use controls to create heating zones and
intelligent controls to maximise the efficiency of the system is
encouraged.
----------------------------------------------------------------------------------- back to top >>
8.2.3 The use of low carbon technology.
- Modern wood pellet boilers and automated room heaters are good,
practical alternative to oil/LPG. These carbon neutral heating are as
efficient as an A rated boiler. - Heat pumps are effectively a fridge in reverse, collecting low level heat
from the ground, water or the air and compressing it to provide a
higher level of heat to be used in the property. Ground source heat
pumps are particularly suited to the Peterborough area as the wetter
the soil the better. To achieve optimum return from the ground source
heat pump the system should supply under floor heating, which is best
used in brick, block or stone constructions which act as a store for the
heat. - Solar hot water collectors can be installed on roofs facing from south
east though to south west. A solar hot water system should supply all
of the hot water demand during the summer months and supplement
the secondary heating system (condensing boiler) during the winter.
The solar hot water system is particularly suitable for family properties
where their will be large demand for water. A solar hot water system is
best used with a water heating system where water is stored. Special
hot water tanks with two heat exchangers are used. The collectors are
connected to the lower (larger) heat exchanger and the condensing
boiler that also supplies the radiators is connected to the upper heat
exchanger.
8.3 Energy Efficient Lighting and Appliances
- Low energy lighting should be used through out.
- The use of sun tubes is encouraged. Sun tubes collect external light
which is then bounced down a mirrored tube to where light is required.
Light tubes can be used where there is insufficient room to
accommodate a sky light. - Appliances should be the highest rated available in their class.
The position of electric sockets should be considered to allow
appliances to be turned off.
8.4 Micro Renewable Power Generation
Electricity can be generated using:
- Photovoltaic (PV) array - a semi conducting sandwich of material which
when the energy of the sun strikes it produced an electrical current. In
UK lighting conditions PV arrays should be on a south facing aspect
with no shading of the panel. A typical 2.5khW domestic array will
produce 40% of the households electricity need. - Micro Wind turbine – each turbine has different power curve to give
guidance of the power out put. As a guide a steady wind speed of
6m/s (13mph approx) is required. It is unlikely that a wind turbine will
be viable in a built up area but on a suitable site a turbine can produce
from 20 to in excess of 100% of the household electricity needs.
----------------------------------------------------------------------------------- back to top >>
8.5 Waste Management
The sorting of waste to allow recycling and composting should be considered
in the design to allow external storage and sorting in the property.
8.6 Water Conservation and Management
Sustainable water management measures should be incorporated into design
proposals:
- The amount of water used in the property should be minimised with
the use of flow restrictors, aerated taps and shower heads and super
low water toilets. - The use of water in the garden should be considered, planting of
suitable plants and rain water collection should be considered. - Rain water collection for internal use and recycling grey water for
garden use could be considered. - Sustainable urban drainage should be considered – permeable
surfaces, holding ponds and a green roof may be helpful. Green roofs
also provide high levels of insulation.
Sustainable Drainage Systems (SUDS) offer an alternative to traditional
approaches to managing runoff from buildings and hard standing. SUDS
mimic natural drainage patterns and can reduce water surface water runoff,
encourage recharge of groundwater, and provide amenity and wildlife
enhancements. By employing pollutant trapping and degradation processes,
SUDS can protect water quality.
SUDS approaches include:
- Preventive measures including good housekeeping and rainwater
harvesting. - Reduced UHI effect by filter strips and swales. These are vegetated
landscape features with smooth surfaces and a gentle downhill
gradient to drain water evenly off impermeable surfaces. - Infiltration devices, such as soakaways, which allow water to drain
directly into the ground. - Green roofs (see below) and reuse of water.
- Permeable and porous pavements.
- Basins, reed beds and ponds designed to hold water when it rains.
It is important that consideration is given to long term maintenance
requirements of SUDS, including the need to remove silt, and that space
requirements for maintenance are allowed for in the design.
Green roofs are vegetated roofs, or roofs with vegetated spaces. The main
benefits include:
- Stormwater management and hence potential savings to developers
since the number of drainage outlets required on a building can be
reduced. - Reduced urban heat island effect by reducing building heat loss and
increasing evapotranspiration. - Creating natural green spaces in urban areas bringing benefits for
biodiversity. - Reduced energy consumption and fuel costs, since green roofs
provide cooling in summer and thermal insulation in winter. - Reduced air pollution.
- Extended roof life. The green roof protects the roof’s waterproofing
membrane, almost doubling its life expectancy.
Rainwater harvesting captures and diverts rainwater. The captured water
can be used for irrigation purposes, car washing or toilet flushing. It is
beneficial for two reasons:
- It reduces water demand, easing pressure on the mains water supply.
- It helps to reduce the risk of flooding during storms by storing
rainwater and buffering run-off before it reaches the drainage system.
Typically, rainwater is collected from rooftops and is diverted into barrels or
storage tanks. The amount of rainwater collected from a rooftop can be
significant. A 100m² roof can catch 500 litres of water from rainfall of just 5mm.
----------------------------------------------------------------------------------- back to top >>