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cRRescendo Site Milton Keynes


Project status



Milton Keynes already has a reputation in the UK as an energy pioneer. Designated in the 1960’s as a planned new town, it is located close to London.

The Concerto-Project will comprise 7 blocks totalling 650 dwellings, with retail and community facilities at ground floor on main frontages. All in all, nearly 3,830 people will directly benefit from the project in Milton-Keynes. Because of renewable energy supply and energy savings, the buildings they live in will produce just half the CO2 that would be produced by equivalent dwellings without the measures.

It continues to pursue its vision of a sustainable community with energy efficiency (EE) and the integration of environmental and socio-economic factors.


Site facts and figures

  • Estimated population involved: 3,800
  • Approx. geographical area coverage: Information will follow
  • Approx. energy saving: 38 %
  • Approx. energy from RES: 12% in consumption, 14% in poly-generation



The CONCERTO activities at Milton Keynes comprise the construction of 3 office buildings and 445 residential units taking sustainability in the city to the next level (Picture 1 + 2). High performance standards have been applied for insulation and air tightness. The office buildings have obtained BREEAM excellent rating with an A rating Energy Performance Certificate. The air conditioning of the office buildings uses a four pipe fan coil distribution system that takes heat from the district heating system via plate heat exchangers to secondary heating circuits and to two absorption refrigeration chillers.

The project also aims to give the inhabitants of the dwellings information for monitoring their own energy consumption: there are intelligent energy management systems and displays in some apartments showing exactly how much power is being consumed. The project also features intelligent management on the supply side.

A CHP plant (Picture 3) has been running successfully for a number of years serving many commercial and residential buildings in Central Milton Keynes. The 6 MW CHP station (Picture 4) is powered by gas engines and distributes heat (hot water) and electricity via a private wire and heat network to the two CONCERTO developments, and to other existing and planned buildings in the area. The network is capable of extension to accommodate local growth. A measure of its success is an extension to serving the new constructed “Network Rail” headquarters building (37,790 m²) at the former Hockey Stadium site.

A large-scale photovoltaic plant (165 kWpeak) has been installed on the central bus station (Picture 5). Read about the monitoring approach in the “More Detailed” section.


The Monitoring Approach

The new Energy Centre in Central Milton Keynes has two gas-fired combined heat and power (CHP) units with an electrical capacity of 3 MWe each. The CHP units are supplemented by a 10 MW gas-fired peak load boiler and three thermal storages with a total capacity of 480 m³.

The CHP units are operated on heat demand from the district heating system. In times of high heat demand the gas-fired boiler fills up the gap; on light load the CHP units back-off to approximately 50 % full load.

The generated heat is used in the district heating system with a 30 °C temperature drop at full load and the generated electricity is delivered to the site via an 11 kV private electricity grid. The Energy Centre is also connected to the national electricity grid for supplementary electricity supply or to export power. The nominal electrical efficiency of the CHPs is 42 % and the thermal efficiency 43 %.

The operator of the Energy Centre monitors with electricity and heat meters the demand side and the CHP plant for the supply side performance. The metering concept is shown in Figure 1.

The electricity profile (Figure 2) shows an increasing electricity demand in the winter period due to the higher demand for lighting and possibly for electric supplementary plug-in heaters. Compared to 2009, the imported electricity from the grid has been reduced by about one third in 2010 so that 73% of the electricity used in the private wire was delivered by the CHP units. As far as the heat for the district heating network is concerned, 97 % are generated by the CHP units and only 3% come from the supplementary gas-fired boiler. The operation of the two CHP units is shown graphically in Figure 3 and Figure 4.

During 2009 CHP unit 1 was the lead machine in 2010 CHP unit 2 took the load. Due to some vacancies in the office buildings and the resulting lower heat demand the peak heat loads are matched during the reported period with the capacity of one CHP unit.

Furthermore, the Energy Centre is managed that heat dumping is minimised. The decision to run the CHP units when the there is no heat demand on the district heating is made on the basis of the spot prices of grid electricity and gas. If it is more economical to use electricity generated by the CHP than grid electricity, the CHP units run and the resultant heat is rejected to the air. Heat dumping ranges between 2% and 10% of the total delivered heat from the CHP units.

Lessons learnt

The following information has been gathered as part of the CONCERTO Premium policy research.

Benefits of CONCERTO:

Key benefits:

Milton Keynes is seen as a forerunner in the field of sustainable energy – especially in terms of special planning strategies. The project added to already high-profile, groundbraking developments in Milton Keynes. CONCERTO raised the profile of renewable energy and polygeneration. Due to the central location it brings car-free development within reach (though the project as such is not car-free) – this is new in the car-dependent Milton Keynes. High quality sustainable development schemes have been delivered and, most importantly, these demonstration projects have proven functional with very tangible benefits in terms of energy efficiency. The Central Milton Keynes demonstration projects are not merely tokenistic but an important and integral part of the urban fabric, setting new standards of sustainability and energy efficiency to which future development schemes should aspire. The project offered the opportunity to obtain quantitative and qualitative data on householders with changed attitudes towards Energy Efficiency and Renewable Energy Services, as well as the chance to undertake social research regarding quality of life and for gauging expectations and satisfaction with new/ refurbished homes as well as understanding householder behaviour. The building complex “C4.1/Vizion” demonstrates best practice and innovation in high-density, mixed use development on a scale not previously seen in Milton Keynes with advanced energy performance.  This is a very significant achievement in a city, which, although designed to incorporate a range of residential densities, nevertheless has a very low residential density relative to older cities. It represented a ‘step change’ in terms of sustainability for a large scale, residential based, mixed use scheme in the context Central Milton Keynes. This development raised the benchmark for new residential based development schemes in Central Milton Keynes. The complex “B3.2N/Pinnacle” raised the bar in respect of office development. It was the first BREEAM ‘Excellent’ rated office scheme in Central Milton Keynes.  This scheme set the standard for subsequent office development in Central Milton Keynes, such as Network Rail’s ‘Quadrant’ which also achieved a BREEAM ‘Excellent’ rating. The competition winning design by q2 Architects for the C4.1/Vizion –building is a vibrant high density mixed-use development which not only creates a landmark for Central Milton Keynes but also addresses the city’s sustainable development objectives.  Significantly, it was the first scheme to respond to the new Development Framework for Central Milton Keynes which aims to create a new urban environment. It’s high quality landscaped courtyards are a major feature of C4.1/Vizion, with the large, ‘green roof’ of the Sainsbury’s store creating a magnificent podium garden for residents.  Frosts, landscape gardeners, won a Bali award for the landscaping in 2009. It demonstrates best practice and innovation in high-density, mixed use development on a scale not previously seen in Central Milton Keynes. The HCA (Homes and Communities agency, a UK government agency), was the key partner for CONCERTO.

Skill development:

A first information meeting was held with future tenants before they moved in, to make them acquainted with the project and to provide them with a basic understanding of the planned and realised measures. A one day information event has taken place in November 2010 in the foyer of a CONCERTO apartment block to hand out surveys and answer residents´ questions.

Local economic effects:

Socio-economic research pertaining to employment creation.


Barriers encountered:

Legal barriers:

The Retro-fit of the PV array on the former bus station had to be undertaken in a manner which respected the architectural integrity of the building [i.e. requirement of Milton Keynes Council Development Control planners]. Solutions: The original architect of the bus station was employed to input at the planning and design stage to draw on his knowledge of the building and to produce a sensitive design solution that would secure the required planning consent. Commissioning the involvement of the architect who had originally designed the [former] bus station in Central Milton Keynes proved, with hindsight, to be a prudent decision since this expedited both achievement of the required planning consent and, indeed, subsequent installation of the PV array, in accordance with the cRRescendo/Concerto project timeframe. A bespoke design solution also had to be devised to protect the recently renewed roof membrane. The need for a bespoke design response increased the cost of both project design and implementation. This illustrates that a ‘retro-fit’ or ‘non-integrated’ installation can prove more challenging and costly to install as a consequence of having to address constraints associated with planning policy or the existing building design/fabric in order to realise environmental aspirations.

Technical barriers:

Observations on performance, based on Arup’s monitoring findings, were as follows:

The commercial buildings require attention as they are under performing and they have a major impact on the energy and carbon emissions from the development. Additional data acquired for the electrical consumption of the commercial properties [i.e. since the first issue of the monitoring report] indicate that these properties are still exceeding electrical consumption targets, by at least 35% for B3.2N/ Pinnacle and 200% for CBXIII. The energy management of the commercial developments should be reviewed as there is a high electrical demand evident during the unoccupied periods – over-night and weekends where electrical demand rarely falls below 50% of the daytime peak. The building management system and controls in the commercial buildings should be checked against occupancy as the energy demand is indicating operational periods in excess of 16 hours a day and weekend running. The control algorithms should be checked in the B3.2 commercial buildings as they are showing chiller operation during some of the most severe cold periods. The potential to use free cooling at these times should be explored. The absorption chillers serving B3.2 offices use a large proportion of the site heat energy (33%) but are demonstrating very poor performance figures. The machines are in urgent need of a thorough servicing to correct this situation. The thermal losses in the district heating system are indicated at 9% of delivered heat, for the year March 2010 to April 2011 which is expected performance. However previously to this period losses were seen to be much higher, so monitoring should be continued to ensure losses remain low. Comparing the electricity consumed at an individual building level with that supplied to the private wire system suggests a loss of 9%. This appears to be excessive and assuming losses in the transformers to be about 6% the remaining 3% needs to be accounted for. However, the fact that systematic monitoring was undertaken means that energy leaks could be identified and can now be targeted.

Economic barriers:

The financial risk associated with new technologies applied. Significant economic barriers and risks were encountered during the planning and implementation stages. Due to the context of an unprecedented economic downturn, which had an unprecedented adverse impact on the UK development and construction industry thus severely hampering HCA’s ability to fulfil obligations under the Concerto agreement. The substantial new developments on which the original proposal was based did not go ahead. Furthermore, regarding the management and monitoring there have been concerns over timeliness and delays, particularly concerning the performance of the Esco.

There were a number of constraints on relating to the running of the CHP. One of the crRescendo Buildings (the Pinnacle) was not close to the CHP, meaning that connection was costly. Regarding CHP: Management – The involvement of an unfamiliar third party and set of processes such as the ESCO in already complex development schemes does cause concerns from developers regarding potential delays and costs. Procurement and OJEU - given the specialist nature of this project the view taken at the time of their selection was that the ESCO were the only partner able to provide CHP in the form agreed. This followed a “market test” aided by the National Energy Foundation. The original PDA was amended to reflect the experience of the first phases. The HCA (or its successors as in January 2013 the HCA sold the bulk of its landholdings and assets to Milton Keynes Council) will still be obliged to trigger the PDA viability process for the remaining development phases, but under the revised PDA it will not be obliged to make any further contributions, unless it chooses to gap fund on viability grounds. The changes to the PDA also address processes for dealing with negotiated land disposals, by imposing a revised feasibility and viability programme. The ESCO will need to work on much shorter timescales in order for developments to be connected to the CHP supply, in turn enabling developers to incorporate the necessary CHP service requirements into the development designs. Changes also included improved methods of agreeing avoided costs between the ESCO and the developer to ensure developers and the HCA are aware of the connection costs as early as possible. The PDA was varied to allow the ESCO to make connections to existing buildings outside of the PDA boundary to increase efficiency Value for Money (VfM) - Project costs funded by the HCA are around £3m. The project has delivered a supply to over 45,500m2 net of commercial and retail space plus 925 residential units. The PDA anticipates repayments to HCA after the ESCO reaches its defined viability threshold. The HCA had to provide funding in order to make connection viable for the ESCO. The flexibility shown by the EU in terms of enabling the cRRescendo/Concerto demonstration project to be revised and extended was, in the context of Milton Keynes, critical to achieving physical [development] deliverables.

Social barriers: The survey amongst residents undertaken by Oxford environmental change institute showed a) that many were not aware of living in a particularly energy efficient home and b) it was not perceived to be important – important is only the location. Overall, the social research results highlight the important interaction between energy efficiency measures built into a building and occupant behaviour. Some ‘energy-efficient’ technological measures incorporated into the building design might be circumvented by occupants on the grounds of improving comfort. The research suggests that there is still work to be done with regard to winning the ‘hearts and minds’ of some ‘built environment’ consumers and that more needs to be done, perhaps by way of education or promotion, to convince them of the merits - both collective and individual - of embracing ‘green’ principles. The research highlights the predicament and problematic of trying to measure the effects of technical interventions which are not readily apparent to occupants. Also, comments have been made to the effect that cRRescendo development in Milton Keynes is not sufficiently prominent and that development with energy efficient credentials in other UK cities is more conspicuous. Possibly based on the fact that the PV arrays that have been installed on the former bus station roof are hidden from sight in order to meet development control requirements and to respect the architectural integrity of the building - and that the stunning landscaped podium garden at C4.1 is not visible or publicly accessible.


Success factors identified:

Technical Success Factors:

A successful component of the MK demonstration project has been the delivery of the CHP engine connecting via a ‘private wire’ network to several large scale buildings in the city centre. The CHP in Central Milton Keynes was the first to be installed in a modern city centre in the UK. The next step might be to investigate opportunities to roll out CHP with alternative fuel sources which do not rely on gas. Confidence in the CHP system is such that it has already been expanded beyond the scope of the cRRescendo/CONCERTO demonstration project [i.e. connection to Network Rail’s recently completed ‘Quadrant’ headquarters in Central Milton Keynes ].

Social Success factors:

CONCERTO project provided information to tenants how monitor their own energy consumption. Furthermore, enlightened and receptive developers were key. The flexibility shown by developers of, then, still evolving schemes [i.e. C4.1/’Vizion’ and B3.2N/’Pinnacle’] was critical in helping to achieve the required physical outputs [e.g. enhanced building fabric]. These were developers who were able to see the benefits of sustainable technologies and development form for their clients.

Institutional success factors:

The role and extended powers and responsibilities of the “Milton Keynes Partnership”, a subcommittee of English Partnerships, a national government agency was a success factor, providing strong support from a dedicated project delivery team, which set aspirational briefs for developers. etc., and brought drive and expertise. It was set up specifically as delivery vehicle to turn governmental policy on sustainable urban growth into real projects. The Partnership was able to decide on spatial planning matters (in so far taking over responsibilities from the municipal planning department). One of its tasks was the briefing developer teams on sustainability targets. Furthermore, Planning instruments at the national and local level were fundamentally important in terms of providing the necessary policy ‘hooks’ to deliver the kinds of sustainable development required of the Concerto/cRRescendo project. Ambitious and pioneering local policies developed by Milton Keynes Council paved the way for new development to embrace sustainable construction and renewable energy. During ‘post-project’ interviews there has been developer acknowledgement that the involvement of a government agency, working to a remit of raising design and sustainability standards through the production of ambitious site briefs. Put simply, EP/MKP/HCA was able to produce development briefs for its sites which successfully ‘raised the bar’ in terms of the design and sustainability of development.

Economic success factors:

The Homes and Communities Agency (HCA) is a new government agency which combines ‘The Housing Cooperation’ (Government funded body for social housing). The purpose is to manage land owned by the government, to buy derelict land (run down town centres, contaminated land, minefields, ministry of defence land etc.) and to invest in regeneration projects. The project idea came from HCA as they were looking into a ‘sustainable residential area’ and were trying to find an additional source of funding. HCA owns the land on which the development takes place, before Milton Keynes was built it was farmland and bought by the government to build this ‘new town’. HCA was therefore able to define all requirements for a new site in a development brief.


The adverse economic affected development viability to the extent of necessitating a substantial revision of the development schemes that were utilised to deliver the outputs required of the cRRescendo/Concerto project. This demonstrates the importance of adopting a flexible approach to project planning. CONCERTO fitted well the spirit of the age, when sustainable energy projects were high on the agenda. It complemented well the objectives of the construction projects already planned.


Legacy – follow-on projects:

In 2012 the BREEAM ‘Excellent’ rated Network Rail headquarters ‘Quadrant’ development, comprising 38,000 sq. m connected to the CHP system in central Milton Keynes. The ‘Quadrant’ is located outside the PDA area and therefore there was no obligation for the client to connect to the district CHP system. This expansion of the CHP system outside the perimeters of the original Project Development Agreement (PDA) area is a positive indicator of the confidence now being shown in the ability of the CHP to deliver cost effective heat and power. The decision for Network Rail to connect to CHP was made on the basis of a process which involved the consideration of other, competing, energy providers.


Legacy - Policy Developments:

The development of the local plan which contained the important Policy D.4, requiring zero carbon development or offset payments, if this cannot be achieved, was developed in parallel with CONCERTO-processes - there was cross fertilization.

The CONCERTO approach

Each building will have improved insulation, air-tightness and ventilation systems with heat recovery to reduce heat demand giving significant energy savings against the national standard.

In addition, water conserving fittings throughout will reduce demand for hot water.

Poly-generation in the Milton Keynes community involves a gas-fired CHP system (3MWe/3.1MWth) with a private wire electricity distribution network.

Specific innovation within the context of the UK industry includes the integration of gas-fired CHP, PV, and ground source heat pumps to serve a city centre community. In addition, intelligent management systems are being developed to optimise the energy consumption on both the supply and demand sides.

Use of Renewable Energy Sources

Advanced means for increasing energy output from RES can be seen in the Milton Keynes project, which will deliver 390 kW produced from the PV systems occupying 20% of the roof space, in addition to 277kW from ground source heat pumps serving ground floor retail units.


Integrated design and construction of environmentally responsive buildings with RES and EE measures in Milton Keynes have been ensured and will lead to projected savings of up to 49% on CO2 emissions per year in the Milton Keynes community.


Charles Amies
Homes & Communities Agency, Milton Keynes
United Kingdom

Building aspects

  • Installed Renewable Energy Sources
  • photovoltaic

Thematic Field

  • New Building(s)

New residential flats

View more visualisations of cRRescendo Site Milton Keynes