Argent (King’s Cross) LtdArgent (King’s Cross) Ltd King’s Cross Central Energy Assessment...

Argent (King’s Cross) Ltd King’s Cross Central Energy Assessment September 2005

Ove Arup & Partners Ltd 13 Fitzroy Street, London W1T 4BQ Tel +44 (0)20 7636 1531 Fax +44 (0)20 775 www.arup.com

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Ove Arup & Partners Ltd rev001 28 September 2005

Argent (Kings Cross) Kings Cross CentralEnergy Assessment


Ove Arup & Partners Ltd rev001 28 September 2005

Contents Page 1 Executive Summary 1 2 Context 3

2.1 The London Plan 3 3 Assessment method 4 4 Baseline Energy / Carbon Benchmarks 6 5 Energy Efficiency Measures 7

5.1 Building energy efficiency measures 7 5.2 CHP 8

6 Renewable energy sources 12 7 Future proofing 17 8 Conclusion 19

Appendix 1: Preliminary renewables assessment

20

Appendix 2: Floor Areas and Energy Indicators

21

Appendix 3: Building Regulations

23

Appendix 4: CHP Assessment

24

Illustrative scheme plan for the southern hub

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Page 1 Ove Arup & Partners Ltdrev001 28 September 2005

1 Executive Summary

In May 2004 Argent (King’s Cross) Limited, London and Continental Railways Limited and Exel plc (“the Applicants”) submitted planning and heritage applications (“the Applications”) to the London Boroughs of Camden and Islington for the King’s Cross Central development (“KXC”). KXC would deliver the phased, comprehensive, mixed used development of some 27.2ha of former railway lands within the King’s Cross Opportunity Area.

The Applications are supported by an Environmental Sustainability Strategy (“ESS”), which explains how the Applicants would address the environmental and natural resource issues which form one aspect of sustainable development. The ESS sets targets for reduced carbon emissions, to be delivered through using energy efficiently, the use of renewable energy, and supply efficiency measures.

Since May 2004, the Applicants have held extensive discussions with London Borough of Camden and London Borough of Islington and others (including the Greater London Authority) about various aspects of the Applications, including environmental performance and sustainability. The Applicants have also taken account of the many written representations received by the London Boroughs of Camden and Islington, during formal consultation. As a result the Applicants are now proposing a number of amendments to the Applications, incorporated within Revised Development Specifications for the Main Site and Triangle Site.

The Applicants have begun to take forward certain aspects of the ESS by conducting feasibility assessments into several of the technologies that could potentially reduce the carbon emissions arising from occupiers’ energy use. As a result, the Revised Development Specifications (September 2005) make commitments to several of these technologies including: District Heating and Combined Heat and Power incorporating at least one fuel cell; 14 wind turbines; pipe-work for ground source heat pumps; photovoltaics; and solar water heating.

This Energy Assessment addresses the energy demand of the proposed King’s Cross Central development, as set out in the Revised Development Specifications. It demonstrates the steps taken to apply the Mayor’s Energy hierarchy and shows how the development would generate a proportion of the sites energy needs from renewable energy technologies.

The energy priorities for KXC are to:

• achieve ambitious energy targets and significantly reduced carbon emissions levels

• use ‘performance based’ targets to enable each phase to select the most cost-effective means of achieving the targets

• maintain the ability to meet targets as and when the development adjusts to suit the market

• allow progressive implementation of new energy efficiency and renewables technologies as they become cost effective and supply chains mature

• be auditable with simple verification

• incorporate “future-proofing” in anticipation of continuing carbon reductions over the full building life Illustrative View of Pancras Square

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Accordingly, the King’s Cross development partners have made important commitments to using less energy and supplying energy efficiently. King’s Cross Central buildings would be at least 5% more efficient than the Building Regulations in force at the time. District Heating and Combined Heat and Power systems (incorporating at least one fuel cell) would deliver additional savings in carbon emissions. Together, these building energy efficiency and supply efficiency measures are likely to save over 5,000 tonnes of carbon per annum, a reduction of 32%, compared with “ current business as usual” energy benchmarks.

The King’s Cross development partners have made additional commitments to renewable energy, in particular photovoltaics, ground source heat pumps, solar thermal and wind turbines. These measures are calculated to save a further 71 tonnes of carbon per annum and they represent an important local, regional and national contribution to renewable energy policy.

With these measures, King’s Cross Central would use less energy, use renewable energy and supply energy efficiently. Together, they are likely to deliver annual carbon savings of some 33%, compared with “current business as usual” energy benchmarks.

The long-term aim is for King’s Cross Central to achieve a 60% reduction in carbon emissions from 2000 levels, by 2050. The King’s Cross development partners’ investments in district heating and Combined Heat and Power systems would ‘future proof’ the development and provide the means to achieve this target, of which the first step would be by using top-up boilers fired by biofuels, should market, supply chain and other conditions allow.

This Energy Assessment shows that the future implementation of biofuel technology could save a further 1,000 tonnes of carbon annually and bring the proportion of the development’s energy needs generated on-site by renewable technologies up to 10%. The total carbon savings would then be some 39%, compared with “current business as usual” energy benchmarks.

Illustrative view looking north-west from new bridge linking Camley Street Natural Park with King's Cross Central




2 Context

2.1 The London Plan

The UK national planning system refers to sustainability as its underlying principle, as outlined in PPS1 (Planning Policy Statement 1).

The Regional Spatial Strategy for London, in the form of the London Plan, reflects this with particular policies related to climate change and carbon emissions.

London Plan paragraph 4.18 refers to the carbon dioxide emission reduction targets in the Mayor’s Energy Strategy - ‘20 per cent [reduction] relative to the 1990 level by 2010 as the crucial first step on a long-term path to a 60 per cent reduction from the 2000 level by 2050.’

London Plan Policy 4A.8 (Energy assessment) states that:

”The Mayor will and boroughs should request an assessment of the energy demand of proposed major developments, which should also demonstrate the steps taken to apply the Mayor’s energy hierarchy. The Mayor will expect all strategic referrals of commercial and residential schemes to demonstrate that the proposed heating and cooling systems have been selected in accordance with the following order of preference:

passive design;

solar water heating;

combined heat and power, for heating and cooling, preferably fuelled by renewables;

community heating for heating and cooling;

heat pumps;

gas condensing boilers &

gas central heating.”

London Plan Policy 4A.9 states that ‘The Mayor will and boroughs should require major developments to show how the development would generate a proportion of the site’s electricity or heat needs from renewables, wherever feasible.’

This Energy Assessment responds to the above planning context.

Background: The Mayor’s Energy Hierarchy

In his Energy Strategy the Mayor has defined an ‘Energy Hierarchy’ (presented below) to help guide decisions about which energy measures are appropriate in particular circumstances. When each stage of the Hierarchy is applied in turn to an activity, it will help ensure that London’s energy needs are met in the most efficient way:

1. Use less energy (Be lean) 2. Use renewable energy (Be green) 3. Supply energy efficiently (Be clean)

It is therefore important for energy efficiency as well as renewable energy to be considered in each new development in London. This means that the buildings will use less energy and therefore would need to use a smaller amount of renewable energy to supply the same proportion of the site’s needs.




3 Assessment method

This assessment following the principles behind the Renewables Toolkit (ref London Renewables ‘Integrating renewable energy into new developments: Toolkit for planners, developers & consultants’), namely:

1. Establish energy & carbon benchmarks for ‘current business as usual’.

This is deemed to include energy use directly attributed to the building occupant and their installed systems in addition to the building envelope and base systems provided by the developer.

2. Identify extent of energy demand reductions and hence the expected energy demands.

This includes energy efficiency measures in the buildings, the choice of fuels (for example for the residential), and energy supply efficiency, Combined Heat and Power (CHP) together with localised district cooling.

3. Identify extent of renewable energy sources appropriate for reducing carbon emissions.

This assesses those technologies which might form part of the development specification and identifies how further reductions could be achieved if market obstacles are reduced.

The results are presented in terms of:

• Energy and carbon levels for the ‘current business as usual’ benchmark;

• percentage carbon savings due to building energy efficiency measures including an assessment of the imminent Building Regulations changes;

• Installed capacity of potential CHP;

• Installed capacity of potential renewable energy systems; and

• Percentage of energy use (measured in carbon) met by potential renewable energy systems.

Figure 1. Aerial view of illustrative scheme looking west




In general the ‘current business as usual’ benchmarks are sourced from industry “good practice” guides. These reflect energy monitoring of buildings carried out during the early 1990s which are now deemed to reflect current (2002 Part L Building Regulations) statutory minimum standard building practice. Where data is not readily available, estimates and other data sources have been used (see Appendix 2).

The assessment is applied to an illustrative build out of the total floorspace applied for. Whilst this is only one of a range of combinations of land uses that would be permitted by the Revised Development Specifications, it represents a likely scenario, from which one can examine likely energy consumption and interaction between uses for the development sought by this energy assessment. As phases and buildings come forward, each application or group of related applications for approval of reserved matters would be accompanied by an illustrative build out plan and an Environmental Sustainability Plan as indicated in section 7.14 – 7.16 of the Implementation Strategy. The Environmental Sustainability Plan would explain how the design of development forming part of each major phase responds to the commitments, targets and aspirations set out in the Environmental Sustainability Strategy and this energy assessment. It would include a site wide Infrastructure and Utilities Plan to explain: the works that would be undertaken as part of each major phase; how those works relate to the long-term strategy for site-wide infrastructure and utilities; and the findings of any relevant feasibility studies undertaken.

Ideas for the Granary Complex

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4 Baseline Energy / Carbon Benchmarks

Figure 2 provides energy consumption benchmarks for the illustrative build out , together with associated carbon emissions, assuming a ‘current business as usual’ approach to energy design and minimum compliance with statutory requirements. This is deemed to include energy use directly attributed to the building occupant and his installed systems, in addition to the building envelope and base systems provided by the developer. This data provides the baseline against which the energy efficiency improvements and renewable energy carbon savings set out in the ESS and this energy assessment can be assessed.

Annual delivered energy requirements:

Annual carbon emissions:

Serviced floor areas

Electricity Gas Electricity Gas

Total carbon

emissions

Fuel carbon emission factor (kgC/kWh) 0.118 0.052

Units m2 kWh/year kWh/year kgC/year kgC/year kgC/year

Retail 31,890 8,709,400 5,139,800 1,027,200 266,400 1,293,600

Uses within D1/D2 68,480 5,674,440 18,768,700 672,200 972,981 1,642,200

Hotel 10,650 1,160,800 3,758,700 136,900 194,900 331,800

Air-conditioned office 174,990 18,548,400 19,968,900 2,187,500 1,035,200 3,222,700

Prestige air-conditioned office 197,560 43,859,300 26,496,900 5,172,600 1,373,600 6,546,200

Residential 160,250 21,897,400 0 2,582,500 0 2,582,500

Basement/MSCP/Infrastructure 112,440 8,702,800 0 1,026,400 0 1,026,400

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Site total 756,250 108,553,400 74,133,500 12,802,300 3,843,100 16,645,600

Notes: 1. Based on Renewables Toolkit Table 7

2. The “serviced“ floor area is the total amount of floorspace occupied and has been taken as 90% of the gross external area.

Figure 2. Benchmark energy demands and carbon emissions for King’s Cross Central (‘current business as usual’)




5 Energy Efficiency Measures

The Applicants are committed first to seek reductions in carbon emissions resulting from energy use within the King’s Cross Central development, through energy efficiency measures. These measures are:

• Building Efficiency Measures – The Applicants are committed to achieving a 5% improvement in carbon emissions performance, over that permitted under the Building Regulations current at the time the building is designed.

• District Heating and CHP – The development would make use of district heating/Combined Heat and Power (CHP) systems, including at least one fuel cell to show-case that technology. Development within development zones A, B, J, K, L, N, P, Q, R, S and T would include the necessary pipework to connect to district heating/Combined Heat and Power (CHP) systems.

In aggregate these energy efficiency measures could deliver a 32% reduction in carbon emissions when compared with the benchmark figures in figure 2, and a 41% reduction (averaged across the various building types) when compared with the current 2002 Building Regulations.

5.1 Building energy efficiency measures

The choice of which efficiency measures to implement to achieve the specified carbon improvements will be made during each building’s detailed design stage. A wide range of options are expected to be tested to ensure the most cost effective measures are implemented with solutions likely to change, depending on when each building is started. During the extended build-out period more energy efficient products and systems are likely to enter the market place.

The Applicants have targeted to achieve an energy efficiency (and hence carbon reduction) improvement of 5% better than the contemporaneous Building Regulations. For example, for buildings for which design is now starting, the target would be an improvement of 5% on the imminent 2005 Building Regulations standards, which represents a ∼30% reduction on current 2002 Building Regulations. This is deemed to be a building energy demand reduction from the base building and its associated systems. It does not include systems installed by occupants that are not covered by the Building Regulations and are not within the direct power of the developer to control.

Verification that the individual building designs meet this performance standard would happen at two stages:

• When reserved matters applications are brought forward for each building, the Applicants will set out the strategy to meet the reduced carbon emissions targets, in the context of the particular building design. This strategy ensures that a sufficient level of design input goes into the physical form and building envelope submitted for approval of reserved matters, to ensure that the targets are realistically achievable though subsequent detailed design, when individual plant sizing, glazing specification etc would take place.

• The detailed information confirming each building design is capable of achieving the targeted carbon improvements will become available at the end of the detailed design stage, at which point the statutory Building Regulations Part L carbon assessment and formal submission is made. Using the standardised Part L assessment methodology, the Applicants/designers would indicate how the building design improves on the contemporaneous Building Regulations by way of energy efficient and renewable energy measures. This formal Building Regulations submission would be available for inspection by the local planning authority. It is anticipated that this will also form the basis of the building ‘asset’ labelling as required by the EU Energy Performance of Buildings Directive, due to be implemented in 2006, albeit that this has not yet been confirmed in detail.

The carbon emissions target is applied to the base building and its associated systems and does not take into account any further energy efficiency / carbon reducing improvements that would be gained by using CHP and renewable energy sourcing.

For high density residential property in London the predominant approach of developers is to use all -electric systems for both space heating and domestic hot water. The current and proposed 2005




Building Regulations allow a relaxation of carbon emissions targets if all-electric systems are used, resulting in significantly higher overall carbon emissions than more traditional gas-fired heating. The Development Specifications indicate that all residential accommodation north of the canal within the main site would benefit from the necessary pipework to be served by district heating / CHP systems and therefore would meet their heat demands through piped LPHW. These buildings would therefore not be subject to this all-electric regulations relaxation and therefore the 5% energy efficiency improvement would instead be applied to the non-electric Building Regulations standard. This means that these buildings would be some 35% more carbon efficient than residential development constructed using the predominant approach in the market.

5.2 CHP

A preliminary study for Combined Heat & Power (CHP) indicates there is considerable potential for CHP to serve much of the development, which would potentially deliver significant savings in carbon emissions. Strategies that could be applied to help harness this potential to its full include: • Appropriate choice of building services systems

• Infrastructure linking together diverse building uses to even-out demand profiles;

• Active electrical distribution across the site, and potentially private wire networks;

• Distributed CHP / energy centres to allow infrastructure capacity (and therefore capital expenditure) to be brought forward as and when it is required; and

• The involvement of a large scale Energy Services Company (ESCo) who could take ownership of implementation and operation, giving early guarantees on energy supply robustness and energy pricing; and make capital contributions towards initial district heating and electrical infrastructure.

Figure 3. Potential CHP Zoning with district heating network and distributed CHP plant

The range of different uses across the development would result in extended hours of energy use and smoothed peaks, as demand switches between different building types. This suits the finite capacity range of CHP and extends the operating hours, improving the possibility of securing a capital return.

As indicated in the Implementation Strategy, the development would start on several fronts and initially the full interconnectivity would not be available. As the development is built out, there would be




improved opportunities to interconnect district heating networks, improving the demand peak spreading potential.

Buildings would need their energy systems to be compatible with CHP to capture this potential. CHP generates electricity and heat simultaneously, so the buildings have to be able to accept heat alongside their electricity demands. This is not currently the norm within the development industry, where it is common practice to use all-electric apartments, all-electric DX cooled retail, offices with rooftop air-cooled chillers, and electric perimeter heating. To capture the potential of CHP, the buildings would need to use low pressure hot water (LPHW) for heating and for generating domestic hot water, and to use a proportion of absorption chilling to use waste heat during the summer months, when there is less demand for space heating. For uses like retail, utilising CHP means the developer incurs extra costs because heating and chilled water distribution and the central plant have to be provided: normally the developer provides a shell, with fit-out being the responsibility of the tenant, who would typically install all-electric individual DX air-conditioning units. It should also be borne in mind that absorption chilling typically requires additional plantroom space and larger capacity heat rejection wet cooling towers, with their additional cost and maintenance liabilities.

The Applicant is intending to set briefs for the individual buildings, to ensure that the building systems design will be compatible with CHP; the Applicant may also seek ESCo contributions where this significantly impacts on capital costs, as will probably be the case for the retail. The Applicant proposes to link all the buildings with significant LPHW demand by way of a community heating pipework networks on a zone by zone basis. This is intended to be serviced by a network of energy centres, with both pipework and energy centres having phased construction to suit the building programme. Initial discussions have started with the relevant approval authorities with a view to using the standby generators normally provided in selected building types as continuously operating CHP units.

CHP ZONE A

CHP ZONE B

CHP ZONE C

CHP engine capacity

(MWe/MWth)

6.5

3

4

Storage tank volume required

(m³)

530

370

480

Supplementary heating from boilers

(kWh/yr)

11,412,331

13,391,670

11,092,017

Cooling by Absorption chillers

(kWh/yr)

7,487,425

2,079,393

3,399,520

Note: Plant unit sizes and capacity division within each CHP zone will be based on development phasing, maintenance and operation criteria. Figure 4. Plant capacities




District cooling has been considered. Its viability is sensitive to the cooling demand levels and the need to minimise standing losses. It is likely that this might only be viable where there are high cooling demand concentrations, for example in CHP Zone A (see Figure 3). The extent of district cooling, if appropriate, would be established when the plant locations are decided in each CHP zone, with absorption chillers and their associated cooling towers either in various central locations or distributed building by building. Capturing a substantial proportion of the revenue received for electricity generated by CHP is fundamental to the viability of CHP. This is normally best achieved through a private-wire electrical distribution system. Without such a mechanism, the operating revenue from CHP would be insufficient to cover its operating costs, because of the low unit purchase price that Energy Supply Companies (ESCo) offer for electricity delivered to the electricity network by private CHP generators. DNOs do however offer substantial discounts on the capital contributions they would otherwise expect from the developer, towards installing the new local electricity distribution network, with associated off site upgrades. Similar discounts from potential private-wire operators would be required to secure the viability of CHP. operation, maintenance, detailed design, capital funding and associated risks and opportunities of private-wire electrical and community heating networks, together with major energy centres, are considerable and not within the normal experience of building developers. Consequently it will be essential for the successful delivery of these at KXC that an (ESCo) takes the lead and is responsible for the energy supply across the site. Enquires to date with potential ESCo organisations have resulted in a reasonable level of interest, but no commitments. One significant obstacle appears to be the funding gap between when the pipe/wire/energy centre infrastructure has to be built and when the ESCo can secure loans against future, speculative energy revenue. Most ESCo's are of insufficient size/experience to obtain unsecured capital advances and hence can only contribute capital after energy supply contract “heads of terms” are signed between the ESCo and energy customers, in the form of building occupiers. The building developer is however unable to make energy purchase commitments now on behalf of future occupiers. The resulting funding gap represents a significant obstacle for the delivery of these innovative energy supply mechanisms. Consequently, it is difficult for the Applicants to make firm pledges on delivery at this time.

Figure 5. A large scale CHP engine

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Nonetheless the Applicants are committed to finding means for unlocking the ESCo model and continue to work with potential energy service providers to overcome these obstacles. Additionally, the Applicants would like to work with the Climate Change Agency (CCA) to see whether their emerging model could achieve this. The CCA ESCo model, with appropriate financial, commercial and political backing, could have the potential to address many of the risks and constraints that affect large scale regeneration such as KXC.

The Revised Main Site Development Specification indicates that the development will include at least one fuel cell, to showcase that technology. Whether this can be delivered early in the development will depend on the availability of match funding and contributions from manufacturers, to assist in prototyping this technology. Fuel cells currently suffer from substantially higher capital costs, compared with conventional CHP. The suppliers anticipate that prices will fall considerably when manufacturing output increases to the extent that production line manufacturing methods can be employed. Provided that sufficient funding is available early on, to make it viable, a 250kW fuel cell would be included within an early phase of the development: if such funding is unavailable then a similar size unit would be installed later in the development, when suppliers deliver on t heir promises of lower prices. A fuel cell would replace a proportion of the conventional gas-fired CHP plant.

Figure 6 illustrates how the development’s energy use would be reduced as a result of the building design energy efficiency measures and the installation of CHP.

Annual delivered energy requirements:

Annual carbon emissions:

Serviced floor areas

Electricity Gas Electricity Gas

Total carbon emissions

Fuel carbon emission factor (kgC/kWh)

0.118 0.052

Units m2 kWh/year kWh/year kgC/year kgC/year kgC/year

Retail 31,890 3,598,952 9,334,418 424,446 483,896 908,342

Uses within D1/D2 68,473 2,415,946 23,328,438 284,928 1,209,346 1,494,273

Hotel 10,650 464,821 6,614,769 54,819 342,910 397,729

Air-conditioned office 174,990 6,952,414 32,895,456 819,940 1,705,300 2,525,240

Prestige air-conditioned office

197,560 16,439,557 43,649,211 1,938,816 2,262,775 4,201,591

Residential 160,250 2,686,301 19,579,236 316,812 1,014,988 1,331,799

Infrastructure 112,440 3,874,736 0 456,970 0 456,970

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Site total 756,250 36,432,727 135,401,528 4,296,730 7,019,215 11,315,945

Carbon emissions reductions due to energy efficiency measures (compared with benchmark figures in Figure 2)

32%

Figure 6. Predicted energy use of the Development with energy efficiency measures (including CHP)




6 Renewable energy sources

The full range of renewable energy sources has been considered for KXC based on those identified as most appropriate by the Renewables Toolkit.

The Applicants believe it is appropriate for a high profile project such as KXC to show that renewables are an important component of future energy supply. Raising public awareness is a vital aspect of this process and hence the choice of renewable systems should provide for a highly visible presence. To this end, the development would include up to 14 wind turbines to be accommodated at roof level and would incorporate and show-case photovoltaics in locations that would receive long periods of direct sunlight.

In addition the development would include pipework for ground source heat pumps within (beneath) Cubit Square and potentially other public realm areas. Any buildings that are predominantly student housing would incorporate solar water heating to meet part of that housing’s domestic hot water needs.

Figure 7. Renewable energy generation

Priority locations / building plots

Installed Capacity

Projected Annual Yield (kWh/year)

Displaced Carbon (KgC/year)

Solar thermal T5, T6 2,220 m² 384,000 23,940

Photovoltaics B2, K2, M1/M2

253 kWp 207,000 23,390

Micro wind turbines

J, Q, T1, R4 120 kWp 140,000 15,820

Ground source heat-pumps

I, H, M 1100 kW 825,000 7,740

Biofuel boilers

Energy centres

see note below

16,844,065 1,027,290

Carbon emission reductions due to renewables (compared with proposed energy use figure 5)

10%

Note: 1.The size of boiler units required to meet annual yield would be subject to detailed design decisions on peak-load or base-load operation

2. See Kings Cross Central Implementation Strategy for specific priority locations. General locations can be found from Figure 8

None of these technologies are well suited to high density urban environments, where the occupied floorspace greatly exceeds the site footprint. While their contribution is small in the context of development as a whole, they nevertheless create opportunities to showcase these technologies. Also, because the Applicants have adopted a strategy of deploying these technologies in the parts of the site where they will be most effective, they will make a significant contribution to the local energy supply requirements of those plots on which they are located.

Biofuel for heating has been identified as the one renewable technology that could potentially make a more substantial contribution to meeting the energy needs of the proposed development. It can compliment gas-fired CHP by providing the supplementary boiler capacity needed during peak heating demand periods. As a technology, it is relatively mature and hence has low technological risks;




however it does require a high degree of maintenance. Furthermore, the supply chains in the UK are fledgling and cannot be guaranteed. It is also less visible than other renewable technologies.

Whilst the Applicants recognise the potential of biofuels to meet the energy needs of the development they are unable to make firm commitments to their widespread use at this time. However if, as expected, the supply chain matures to the extent that heat generated from biofuels can be implemented and delivered to customers as reliably and cost effectively as energy generated from gas, the Applicants would implement biofuel technologies within the development, to supplement the energy supplied through the district heating infrastructure.

If these supply chain conditions are met, it is estimated that the use of renewables could reduce the carbon emissions resulting from energy use within the development (incorporating energy efficiency measures) by up to 10%.

Figure 8. Renewable energy locations




Photovoltaics

The development would incorporate and show-case photovoltaics (PVs) in locations that would receive long periods of direct sunlight. Potential locations include development zone B (in particular the southern façade within development plot B2), development zone K (in particular the Handyside canopy) and development zone M (the Coal Drops). These locations are particularly suitable for PV. They include a high profiles façade facing the main southern entry to the development; a public space canopy; and low rise highly visible roofs in the centre of the site, where PVs could potentially power ground source heat-pumps serving retail/public buildings.

Photovoltaic Panels

Wind turbines

The site is dominated by listed buildings and other heritage features, two conservation areas and St Paul’s viewing corridors, so the scope to integrate wind turbines within the development is limited. However, up to 14 wind turbines would be accommodated at roof level within development zones J, Q, R and T (see Parameter plans KXC014 and KXC021 in the Revised Main Site Development Specification). Typically these turbines have a peak capacity of up to 15kW each, depending on their rotor diameter.

Building Integrated Wind Turbine

Solar hot water

The residential buildings proposed for student accommodation have been identified as most suitable locations for solar thermal systems generating domestic hot water. This type of building use lends itself to the larger solar hot water systems, each serving clustered accommodation, which could be served by shared hot water tanks. This avoids the practical problems of linking roof top collectors to individual dwellings within high density apartment blocks. Increasing the extent of solar hot water across other residential blocks has been discounted because it reduces summer heat demand and hence reduces the commercial viability of district heating CHP.

Solar Hot Water Heating Panels

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Ground source heat-pumps

Ground source heat-pumps are best suited to buildings with roughly equal summer cooling and winter heating requirements, so that across a year the heat extracted and returned to the ground has a neutral thermal polluting effect in the ground. Typically they can serve air conditioned buildings of up to about 4 storeys from the ground below the building, so they are best suited to lower density developments. The buildings identified as most suitable are the low-rise heritage buildings in the Coal Drops containing retail / public uses. To complement the ground source heat-pumps, the same buildings have been identified as locations for roof mounted PV, which could be used to power the heat-pumps, as explained above.

Ground Source Heat Pumps

Groundwater cooling

With current Environment Agency concerns about water extraction and the large volumes of water needed, this renewable energy source has been considered but discounted as a potential option for this development.

Groundwater cooling schematic

Biofuel CHP

The availability of large scale biofuel CHP plant is currently very limited. The more conventional steam turbine configuration is not well suited to serving the energy needs of buildings because poor electricity to heat output ratio. On the other hand, gasifier technology offers the potential for electricity to heat ratios comparable to natural gas fired CHP, however multi-MW sized plant of the size needed for KXC is still only at the prep-production development stage.

Biofuel CHP Plant

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Biofuel Boilers

Over the last twenty years woodchip boiler technology has been developed to an advanced automated level largely due to suppliers based in Austria / Germany. Meanwhile since the Regional Development Agencies were tasked with researching local renewable energy resource, biofuel has been identified as a particular abundant potential resource in southeast England. The current biofuel fuel supply chains are fledgling, presenting a significant risk until government stimulated investment is implemented and takes effect. Nevertheless, biofuel for heating presents the best opportunity to achieve a high proportion of occupier energy needs through renewables.

Biofuel Boiler

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7 Future proofing

The long-term aim is for KXC to achieve 60% reduction in carbon emissions from 2000 levels by 2050. The challenge for a new development is to ensure that sufficient measures are put in place such that the buildings, infrastructure and their energy supply systems enable this to happen if market and other conditions allow.

Various approaches are possible, including designing buildings for demountability with relatively frequent rebuilding to improving contemporaneous standards. Another is to concentrate initial investment in the long-life fabric components and structure. These approaches have merits but tend to be difficult to implement for today’s commercial market expectations.

Figure 9. Annual average of daily heating and cooling within each CHP zone for each construction phase

KXC seeks to create a new vibrant quarter for London with its own unique character and sense of place that will endure and mature with time. The expectation is that its buildings will be refurbished periodically and, over time, replaced but the essence of the streets and places will remain largely unchanged. While statutory standards are likely to continually rise, with particular emphasis on refurbishment of the existing building stock and making the process of individual building upgrading more effective, the wider infrastructure is unlikely to change so easily or so frequently. Consequently, particular consideration has been given to ensuring the KXC infrastructure is able to accept change.

Key to this approach is the Applicants’ decision to commit to providing a community heating network throughout the development. Whereas an electrical infrastructure can accept a multiple of embedded power generation from a multitude of sources with minimum adaptation, matching lower grade energy between generators and consumers is far more problematic. Some say the future will be all electric, but this flies in the face of basic energy physics. Maximising the energy from any source involves producing it at the lowest grade practical. A CHP unit does exactly this; extracting more energy per unit of fuel (or carbon) than it would if simply acting at a power station and delivering only electricity, by capturing the low grade “waste” heat. Thus a strategy that allows for the distribution of lower grade




heat alongside electricity is likely to be able to make better use of a wider range of future energy sources. This could include biofuel serving multiple CHP units, pure plant oil (PPO) or biodiesel plant, processed waste products, anaerobic digestion, or a future London hydrogen network serving fuel cells.

A further benefit of a district heating pipework system is the relative ease with which centra l plant units operated by an ESCo can be upgraded to increase efficiency or renewable energies, when compared with many smaller individual building plant installations operated on behalf of building operators, for whom energy supply is not a core business activity.

In addition to their strategic future-proofing investment in CHP, the Applicants would contribute to a Carbon Fund of £100,000 per annum, for five years starting from year 7, which could be reinvested by the developer or the occupants to instigate and deliver ongoing reductions in carbon emissions, through the application of new technologies, for example bridging funding gaps that would otherwise prevent them from implementing highly efficient / renewable technologies.




8 Conclusion

This Energy Assessment addresses the energy demand of the proposed King’s Cross Central development. It demonstrates the steps taken to apply the Mayor’s energy hierarchy and shows how the development would generate a proportion of the site’s energy needs, from renewable technologies.

The King’s Cross development partners have made important commitments to using less energy and supplying energy efficiently. King’s Cross Central buildings would be at least 5% more efficient than the Building Regulations in force at the time. District Heating and Combined Heat and Power systems (incorporating at least one fuel cell) would deliver additional savings in carbon emissions. Together, these building energy efficiency and supply efficiency measures are likely to save over 5,000 tonnes of carbon per annum, a reduction of 32%, compared with “business as usual” energy benchmarks.

The King’s Cross development partners have made additional commitments to renewable energy, in particular photovoltaics, ground source heat pumps, solar thermal and wind turbines. These measures are calculated to save a further 71 tonnes of carbon per annum and they represent an important local, regional and national contribution to renewable energy policy. The Government advises tha t significant weight should be attached to the wider environmental and economic benefits of all renewable energy projects, recognising that they can provide a valuable contribution to overall outputs of renewable energy and to meeting energy needs both locally and nationally. At King’s Cross, the proposed measures would have particular significance, within a high profile, high density and mixed use redevelopment, adjacent to a major transport interchange in Central London.

With these measures, King’s Cross Central would use less energy, use renewable energy and supply energy efficiently. Together, they are likely to deliver annual carbon savings of some 33%, compared with “current business as usual” energy benchmarks.

The long-term aim is for King’s Cross Central to achieve a 60% reduction in carbon emissions from 2000 levels, by 2050. The King’s Cross development partners’ investments in district heating and Combined Heat and Power systems would ‘future proof’ the development and provide the means to achieve this target, of which the first step would be by using top-up boilers fired by biofuels, should market, supply chain and other conditions allow.

This Energy Assessment shows that the future implementation of biofuel technology could save a further 1,000 tonnes of carbon annually and bring the proportion of the development’s energy needs generated on-site by renewable technologies up to 10%. The total carbon savings would then be some 39%, compared with “business as usual” energy benchmarks.

District heating pipes installed in the ground

©A

rup




A1 Appendix 1

A1.1 Preliminary Assessment of 10% renewables target at Kings Cross

This preliminary assessment gives an impression of the likely scale of renewable technologies required to achieve the Mayors 10% target. The figures show the footprint/ installed capacity required if only one technology were to be used to reduce the site Carbon emissions individually. Please note that this assessment was carried out prior to the more detailed work in this energy assessment, for example on CHP sizing and therefore the numbers should be treated with caution.




A2 Appendix 2

This energy assessment makes working assumptions about energy performance and the energy consumption profile of occupiers, based on current guidance and practice. Due to the extended build out period and mix of uses, coupled with the fact that the occupiers are not known at this stage, these assumptions can only ever be a “best guess” prediction. This appendix schedules the key assumptions used for this assessment.

A2.1 Gross floor areas and uses

CHP Zone A CHP Zone B CHP Zone C

Building type 1st Major Phase

2nd Major Phase

Subsequent Phases

1st Major Phase

2nd Major Phase

Subsequent Phases

1st Major Phase

2nd Major Phase

Subsequent Phases

Totals

Residential - - - 18,830 24,400 13,050 - 29,120 70,490 156,88

0

Retail 790 1,660 10,060 330 5,160 570 - 2,430 4,360 25,360

Office - type 4: Prestige air conditioned

21,210 34,890 156,870 - - - - - - 212,96

0

Office - type 3: Air conditioned standard

- - - 190 39,250 26,650 - 25,520 102,300 193,91

0

Hotel - - - - - - - - 11,830 11,830

Uses within D1/D2 - 890 5,510 38,780 20,260 740 - 390 7930 74,500

Infrastructure: car parking

4,710 4,040 18,220 7,530 4910 3,420 - 25,120 20,050 88,000

For the assessment of energy use a factor of 90% has been used to covert these gross floor areas to serviced floor area.




A2.2 Benchmark for “business as usual” energy consumption sources

Building type

Gas demand for heating

(kWh/m²/year)

Electrical demand for

cooling (kWh/m²/year)

All other electrical demand

(kWh/m²/year)

Reference source

Residential

0 (assumes all electric heating)

0

137

Adapted (see below) London Renewables ‘Integrating renewable energy into new developments: Toolkit for planners, developers & consultants’

Retail 137

78

195

Introduction to Energy Efficiency in shops and stores (EEO) - good practice standard. These values represent an assumed diversity in retail building types

Office -Prestige air conditioned

114 21 201 Econ 19 type 4 – good practice standard

Office - Air conditioned standard

97 14 92 Econ 19 type 3 – good practice standard

Hotel 300 19 90 Introduction to Energy Efficiency in Hotels

– good practice standard

Sports Centre

400

0

140

Energy Consumption Guide 78 pp 21&27 – good practice standard. These values represent a combination of different sports centre types

Cinema / leisure 513 0 128 Energy efficiency in buildings.

Entertainment, 1990

Infrastructure: car parking

0 0 94 Arup assessment of car park lighting and ventilation loads

Infrastructure: external lighting

0 0 22 Arup assessment of external lighting load

For the residential baseline various adjustments have been made to the Toolkit assumption of the carbon emitted by high density residential. This includes the conversion of the Toolkit value to all-electric heating and hot water to reflect London current building practice, and an addition to reflect modern consumer electronics / entertainment etc systems that is otherwise not reflected in BREDEM 12.

The heritage buildings have been treated as new-build. This reflects the fact that they are a relatively small proportion of the overall built area, the Building Regulations expectation is that they will be upgraded to a modern standard (albeit there is allowance for case by case negotiation). Due to their likely new uses, much of their energy use is likely to be as a result of occupier fitout and systems: this component of energy use is largely unaffected by being in a heritage building.




A3 Appendix 3: Building Regulations

The following schedules the assumed proportion of building energy subject to Building Regulations 2005 Part L Draft (issued for consultation in July 2004). This gives an estimate of the energy proportion for each building type that is due to the ‘base-building’ and in the control of the Applicants for applying energy efficiency measures. The remainder is assumed to be related to occupant fit-out and not in the control of the Applicants, other than by way of energy supply CHP. For infrastructure energy uses, the same energy efficiency percentage savings is used as has been applied as the base-buildings.

Building type Proportion of baseline energy consumption assumed to be subject to the Building Regulations

Residential 65% Retail 25% Office -Prestige air 55% Office - Air conditioned 55% Hotel 35% Sports Centre 25% Cinema / leisure 30% Infrastructure: car parking Not covered by Building Regulations Infrastructure: external Not covered by Building Regulations

The predictions of completed development energy take account of the expected 2005 Building Regulations amendments and do not attempt to predict subsequent changes.

A3.1.1 Consideration of Energy Efficiency Measures

The base case assumes that all residential developments have electric heating, but gas central heating systems are assumed in the CHP analysis as part of the energy efficiency measures. This is so that all energy efficient measures can be included within the CHP analysis and that the Carbon displaced by this can be calculated.




A4 Appendix 4: CHP assessment

A4.1 Assessment assumptions

CHP typical operating hours: 3500 - 4000 per year

Part load CHP maximum turn down ratio:

50%

Electrical generating efficiency:

38%

Thermal store sizing criteria: To match weekday profile with least heat demand against constant CHP output at max turndown.

Chilled water systems:

Base-load single-effect absorption chillers coupled with wet cooling towers. This maximises the viable CHP capacity by keeping the heat demand high during summer, with there being strict limits on CHP heat rejection permitted. The single-effect chillers as opposed to double effect chillers also reduce standing heat losses and allow the district heating system to operate at lower temperatures.

CHP Zone capacities: Future detailed analysis will consider the division of these capacities into unit sizes, reflecting phasing and plant operation criteria. This capacity sub-division is likely to affect turn down ratios and should result reduced thermal store sizing.

CHP & local renewable heat: For buildings with their own heat generating renewables (e.g. heat-pumps or solar hot water) their heat demand from the district heating systems is reduced. For CHP capacity sizing, these buildings are omitted from the assessment because, during periods of minimum heat demand, these buildings are unlikely to have a significant heat demand. Nonetheless it is anticipated these buildings will be connected to the district heating system to meet their peak heat demands at other times, extending the periods the CHP can operate at full capacity and hence potentially improving the operating viability.

Energy carbon factors: ETSU 2003 Energy carbon dioxide emission factor for UK energy mix

Grid electricity: Current Grid electricity carbon intensity is constant during the whole build-out period




A4.2 Calculation of CHP size and consequential Carbon reductions

CHP sizing has been assessed based on the floorspace likely to be built out in each development phase. Three CHP zones have been defined, taking account of this phasing, the proximity of appropriate thermal loads and natural boundaries such as the Regents Canal and York Way.

Adjusted Energy Performance Indicators are used to provide demand for heating, cooling and electricity in the development. These indicators are taken from the GLA Energy Toolkit and are referenced to various good practice and Energy Consumption guides. These indicators have been used in calculation with adjusted degree day heating and cooling factors and predicted daily demand profiles to give indication of the variation of heating and cooling energy demand for throughout the year.

The demand for energy during different times of the day and different times of the year is one of the primary influences on the design and sizing of CHP. The daily variation in demand or annual demand is called the load profile. The following example graphs show cooling and heating demands throughout the year for air conditioned offices and private residential apartments respectively. The CHP analysis estimates the future heating, hot water and cooling demand based upon the time of year from adjusted heating and cooling degree day factors and energy performance indicators. Future demand is estimated for development phases within each CHP zone.




0:00

3:00

6:00

9:00

12:0

0

15:0

0

18:0

0

21:0

0

jan weekday

May weekday

September weekday0100200300400500600700800

Cool

ing

dem

and

(kW

)

Time of day

Typical annual cooling demand of air conditioned office areas within CHP zone A in Development phase 1

jan weekdayFeb WeekdayMarch weekdayApril weekdayMay weekdayJune weekdayJuly weekdayAugust weekdaySeptember weekdayOctober weekdayNovember weekdayDecember weekday

0:00

3:00

6:00

9:00

12:0

0

15:0

0

18:0

0

21:0

0

jan weekday

June weekday

November weekday0100200300400500600

700

Heat

ing

dem

and

(kW

)

Time of day

Typical annual heating demand of private residential building area within CHP zone B in Development phase 2

jan weekdayFeb WeekdayMarch weekdayApril weekdayMay weekdayJune weekdayJuly weekdayAugust weekdaySeptember weekdayOctober weekdayNovember weekdayDecember weekday

The following graphs show estimated demand load profiles for the buildings in each development phase of the three CHP zones. Heating and cooling demands are combined together because when required, a significant proportion of the heat from the CHP engine will be used to satisfy cooling load from absorption chillers. Where there is a wide range of building types within a development there will be simultaneous requirements for heating and cooling at different times of the year. In winter there will be some cooling as well as heating in retail developments. Likewise in summer there will be some heating demand for hot water in addition to cooling demand; therefore sizing of CHP needs to take the total thermal load into account.




First Major Phase

First Major Phase + Second Major Phase

First + Second + Subsequent Major Phases

CH

P Z

one

A, J

anua

ry

Zone A January heating and cooling demand (kWh) First Major Phase

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P Z

one

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ust

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zone C

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CHP schemes work best economically when they run for the most amount of time at maximum output. Efficiencies drop as output drops therefore it is often sensible to size the engines so that they can run at rated output for the greatest length of time. This means that the engine can operate at a higher output for a large amount of the time even though it is not covering peak loads. Peak loads can be dealt with by additional boilers or vapour compression chillers, in the case of cooling.

The CHP plant has been sized to cover the base load heating and cooling demand at mid-season periods. This covers a significant proportion of each zone’s heating and cooling requirement and does not require the engine to turn down to inefficient levels but means supplementary heating is required during the winter.




To increase the base load and the time a CHP unit can run for, storage can be used to effectively “smooth” the peaks in the demand (or load) profile. During times of the day when there is too much heat produced by the CHP, heat is put into a store. When the CHP is not able to meet the heat demand, this heat from the thermal store can be used, effectively increasing the baseline demand and allowing the CHP to be sized above the base load. Calculation of storage is carried out by ensuring that there is enough stored thermal capacity when the CHP is not running to cover this deficit and enough space to store excess heat during times when it is not needed.

When a balance has been achieved between the base load requirements of the CHP engine and the size of storage tank, the total thermal and electrical output of the CHP engines can be calculated. This also allows the displacement of Carbon due to energy efficiency measures and CHP to be calculated relative to the “business as usual” base build case.

Zone A (all

phases) Zone B (all

phases) Zone C (all

phases) Total Annual thermal output from CHP

(kWh/year)

20,958,541

9,833,880

13,439,035 44,231,457 Annual heating demand for all

Zone phases (all heating demand) (kWh/year)

21,064,108

19,968,565

19,283,167 60,315,840

Annual cooling demand for all Zone phases (kWh/year)

7,487,425

2,079,393

3,399,520 12,966,338

Annual thermal demand (kWh/year)

31,760,429

22,939,126

24,139,624 78,839,180

Cooling to be provided by absorption chillers (kWh/year)

7,487,425

2,079,393

3,399,520 12,966,338

Cooling to be provided by vapour compression chillers (kWh/year)

-

-

- -

Required thermal load from CHP for cooling (kWh/year)

10,696,321

2,970,561

4,856,458 18,523,340

Remaining thermal load available for heating demand (kWh/year)

9,651,777

6,576,895

8,191,149 24,419,822

Cooling to be provided by vapour compression chillers (kWh/year)

-

-

- -

Electrical requirement for vapour compression chillers (kWh/year)

-

-

- -

Remaining heating load to be supplied by backup boilers

(kWh/year)

11,412,331

13,391,670

11,092,017 35,896,018 Annual electrical demand within

Zone further to energy efficiency (kWh/year)

37,345,455

19,968,565

18,692,304 76,006,324

Energy efficient electrical demand (kWh/yr) 75,320,926

Electricity generated from CHP (kWh/year)

19,053,220

8,939,891

12,217,305 40,210,415

Electrical requirement for vapour compression chillers (kWh/year)

-

-

- -

Gas input to CHP engine (kWhr/yr)

49,901,289

23,414,000

31,997,703 105,312,992 CHP carbon displacement with

engine only (kgC/yr)

602,037

339,761

442,033 1,383,831

CHP hours run (hours/yr)

3,753

3,815

3,911 Storage volume required (m3) 536 374 478 1388

Net gas demand (kWh/yr)

38,546,257

15,676,476

22,361,057 76,583,790

Net electrical demand (kWh/yr) -

22,048,189 -

9,771,648 -

13,577,113 - 45,396,950 Maximum CHP turndown (%) 50% 50% 50%

CHP engine size 6.5 3 4




The heating requirement of supplementary boilers can then be calculated from the deficit between the development heating demand and the annual thermal output of the CHP engines.

Some of the heating requirement from supplementary boilers can be dealt with by biofuel boilers as part of the response to the 10% renewable contribution target. This renewable contribution includes the carbon displaced by agreed fixed renewables (PV, wind, ground source heat pump etc.). The contribution by biofuel boilers can then be calculated taking into account the fixed renewables contribution which further assists in displacing carbon from the overall site.

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