Swansea
Print Workshop @
Kings
Lane Warehouse
now viewing: Kings Lane Warehouse / The New Building / Structural Engineers Proposal / Energy Efficiency
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Energy Efficiency
Energy consumption in buildings is presently responsible for nearly 50% of CO2 emissions in the UK, whilst the construction industry contributes a further 10% to 15% in the extraction, processing and transportation of materials. Clearly the design and operation of buildings can make a significant contribution to the UK Greenhouse Gas Emission reduction under the Kyoto protocol.
The philosophy of sustainability recommends the consideration of the whole life cost of a building, both in terms of economics and environmental impact. Thus with the print workshop buildings, the impacts of ownership and operation exceed those of any new construction or refurbishment. The approach to the construction will be to maximise the efficiency of the building fabric and envelope where possible and the budgetary constraints allow, in order to conserve resources in operation.
This may lead to slightly higher initial capital expenditure on the building elements but the benefit of such an approach is that the installation of expensive mechanical and electrical systems can be reduced or avoided. This in turn gives rise to savings in running costs, the cost of maintenance of the systems and ultimately to the cost of their replacement. The systems that are installed are designed to operate at the peak efficiency, by allowing internal conditions to fluctuate slightly in response to the external climate, and by recognising the response of human beings as part of the system.
Whilst the savings in operating cost might at first appear small it is widely predicted that the cost of energy must rise dramatically in order to reflect the cost of the environmental damage associated with Carbon emissions. The UK Government has already introduced the “Climate Change Levy” on commercial energy consumers and has plans to increase this over time whilst forthcoming legislation will see the introduction of Carbon taxes throughout Europe.
NEW MATERIAL SELECTION
New materials specified for the redevelopment will be evaluated using
the environmental preference method. This method collates data on the
environmental impacts of the extraction, processing, transportation, use
and de-commissioning of common building materials considering health
impacts and toxicology in addition to the external environment. Choices
of suitable materials for each function are presented in order of
environmental preference and any deleterious products highlighted.
The contractor’s supply chain will be encouraged to demonstrate their commitment to sustainable development by working with the design team to identify the sources and the impacts of products supplied for site. Strong emphasis will be given in the specification to the demonstration of sustainable sources of supply through trade certification systems such as the Forestry Stewardship Council (FSC) certification of timber.
ENERGY EFFICIENCY
The opportunity to upgrade the existing building fabric where possible
to current standards of insulation and air-tightness will help to reduce
the demands for space heating and therefore the requirement for gas.
ALTERNATIVE ENERGY SOURCES
During the design development every opportunity will be taken to explore
the opportunities for the cost effective implementation of alternative
energy systems to further reduce the Carbon impact of the print workshop
operations and its operating costs.
The options for alternative energy systems are described below. Considering that a tower block is to be built adjacent to the north of the site we have discounted wind generated power as an energy source.
PV POWER
Swansea is located in the region of reasonable solar power
potential in the UK and has extensive south facing pitched roofs, which
combine to make it an ideal opportunity for solar PV electricity
generation.
PV currently attracts a great deal of interest, both social and political and the opportunity to demonstrate PV power to the visitors to the Print workshop should not be missed. However the cost of the technology is very high at between £4,000 and £5,000 per kW installed.
SOLAR HEATING
PV suffers from very poor energy conversion efficiency due to the highly
intensive process by which the electricity is generated. Typically PV
can only convert 1215% of the solar energy available annually. On the
other hand solar water heating systems are now being manufactured that
are capable of capturing some 70% of the annual solar energy as usable
heat.
The most efficient solar heating units use special optical coatings, developed for the space industry, that absorb photons at all wavelengths, including visible light, and not just the infra red energy. The absorber is then encapsulated within a vacuum tube to ensure that a minimum amount of heat is lost back to the atmosphere. This combination of technology means that useful heat is available even on overcast days when no direct infra red energy is available from the sun.
Solar thermal heating could be used to pre heat boiler water and or provide heat for domestic hot water, where the demand will be greatest in the summer due to the catering offered.
GROUND SOURCE HEAT PUMP
A heat pump is a refrigeration device that provides heating or cooling
to the building using an environmental heat source as the primary energy
supply. The technology makes use of energy stored within the earth,
which comes mainly from solar radiation. At below about 2m the ground
temperature is a constant 12oC which is warmer than the winter ambient
temperatures and cooler than the summer ambient temperatures. In essence
the heat pump extracts the heat from the ground, via a network of fluid
filled vertical or horizontal pipes buried in the ground, and transfers
it to a higher or lower temperature, depending on whether heating or
cooling is required.
Typically this is a horizontal pipework system consists of a flexible pipe laid approx 1 – 2 metres below the ground in a helix arrangement, commonly referred to as a slinky. A relatively large area of land is required therefore this option is not suitable for this project given the constrained nature of the site.
More suited for this project is the use of vertical pipes that penetrate into the earth between 25 – 50m depending on the ground conditions and the building loads. The pipe bore is typically between 0.1 & 0.2 m diameter with a minimum spacing of 5 – 15 meters between adjacent bore holes. The distance avoids any thermal interference between the bore holes. The vertical system is suitable for most types of soil and requires considerably less land than the slinky type. However the cost of installation is high for smaller systems.
Modern systems are very energy efficient. For each kilowatt of electricity used to run the heat pump, four to six kilowatts of heat are delivered to the building.
WATER CONSERVATION
Potable water is fast becoming an extremely valuable resource and
periods of shortage are experienced throughout most of the world. In the
United Kingdom 20 million litres of treated mains water is consumed
every day. However of the water supplied to commercial buildings only 9%
is actually consumed by people for drinking or cooking. The remainder is
used for non-domestic cleaning and by far the majority is used for
flushing toilets.
First and foremost the facilities fittings will be designed to conserve water. The toilets will use low water volume fittings such as spray taps and low flush cisterns. The hot water plant is located close to the main toilet area which will help to minimise water waste through extended draw off times waiting for hot water.
Furthermore it is not necessary to use treated mains water for sewage disposal. It is now becoming common to retain rainwater from roofs for future use in toilet flushing. For the print workshop rainwater could be collected off the roof, where it can be conveniently collected and piped to the basement plant room. Typically the cost effectiveness of rainwater harvesting systems is limited by the need for extensive excavations to locate the storage tanks below ground. Below ground installation is required to keep the water cool and limit biological growth.
However, the redevelopment will free up existing plant area which will allow for the installation of a small storage tank within. This would effectively be below ground whilst avoiding the cost of excavation.
Water from the roof could be drained to the tanks by gravity through a vortex filter, designed to separate off leaves and debris. Water will be supplied on demand to the toilet cisterns by a conventional pressure boosted pumped system with additional UV sterilisation. Mains water will be used to provide flush water in the event that the rainwater tanks have run dry. Rain water distribution system shall be provided around the workshop for non-potable water uses given the requirement that the workshop can have taps running constantly. The plant room mounted harvesting tank shall also have a mains water top up for extended periods of dry weather.
DRAINAGE EMISSIONS
Conserving water brings dual benefits, in that the volume of water saved
translates directly to a reduction in the volume of sewage produced.
Water companies charge consumers for both the volume of water and the
volume of sewage and so the saving is also multiplied. But furthermore
reductions in the volumes of sewage produced lessen the wider impacts of
the building.
The amount of sewage produced by the print workshop is a function of the visitor numbers, not of the number of toilet fittings provided. With the predicted increase in visitor numbers, coupled to the water conservation measures outlined above we would anticipate that the development would have no impact on the local sewage disposal infrastructure.
Vitreous clay below ground drainage and cast iron stacks shall be used to ensure longevity of the system, with sediment traps provided where required. Any hazardous chemical waste will need to be containerised and removed by a registered disposal company rather than flushed into the drainage system.
RECOMMENDATIONS
With the available mains energy supplies on site, the use of renewable
energy for the Print Workshop cannot be considered on purely capital
cost alone. Renewable energy technologies should only be considered in
terms of raising the workshop profile and its application limited to
planning constraints and funding approval. However the potential for
Grant Funding for a PV installation and the opportunity to displace
elements of building fabric are likely to favour this option. However PV
will still only provide a small fraction of the overall annual energy
demand.
For the workshop PV could be incorporated onto the roof. However a full evaluation of the cost benefit would be required when comparing with roof light materials such as polycarbonate.
Solar water heating should be considered for pre-heating the heating and domestic hot water for the toilet and catering facilities.
Ground Source Heat Pumps are becoming more widely used and the cost of the plant is reducing. The main spend is in laying the pipework or drilling the bore holes. The site has limited ground space and it is not intending to carry out any major excavation works as part of this project, which makes the use of a slinky system uneconomic. (Bore holes could be drilled within or adjacent to the building though given the economy of scale it would be many years before the Workshop realised any returns on their capital investment.