Alasdair DonnWillmott Dixon Re-Thinking LimitedJune 2016

EnergyPerformanceReviewSunesis Keynes and Keynes2

A better class of school

1.0 Project Background and ObjectivesA key aspect of the successful delivery of the Sunesis Keynes primary school programme to date has been the degree to which actual energy consumption in-use, and the associated operating costs for clients, has lived up to - and in part exceeded - design expectations.

In-depth monitoring and evaluation of in-use performance was carried out on the first Sunesis Keynes primary school, Oakfield Primary School in Rugby - completed by Willmott Dixon for Warwickshire Council and opened in October 2012.

This programme of performance monitoring was then extended to cover a further five Keynes and Keynes2 primaries constructed over the period 2013-2015 in order to assess how consistently the performance expectations of the Keynes standard school design were realised in practice.

The schools studied and compared were as follows:

School Location Model GIFA m2

Oakfield Primary SchoolRugbyWarwickshire

Keynes 1FE 1184

New Arley Primary SchoolWarwickshire

Keynes 1.5FEN 1794

Ashcombe Primary SchoolWeston-super-MareNorth Somerset

Keynes 2FEN 2167

St Anne’s Primary SchoolWeston-super-MareNorth Somerset

Keynes2 1 FEN 1420

School Location Model GIFA m2

The Bemrose Primary SchoolDerbyDerbyshire

Keynes2 1.5FEN 1794

Kempston Primary SchoolKempstonBedfordshire

Keynes 2FEN 2167

2.0 Energy Performance AnalysisIn analysing and comparing energy performance data of the 6 schools, the key aspects that were considered were:

How the actual total energy usage in a 1 year period compared with target total energy usage from design predictions developed for the Keynes models.

These target totals were developed during the original Keynes design development phase in 2012/13 and included all electrical energy usage from all building services (heating, hot water, pumps, fans, and lighting) and installed equipment (appliances, IT/servers, kitchen equipment and external lighting) based on assumptions in terms of hours of operation, internal regimes etc.

The target totals were the basis of operating cost estimates provided under a number of client contracts.

How the energy use breakdown across heating, lighting, power etc varied from school to school and with time.

These energy use breakdowns were gathered during monitoring studies on 3 of the 5 schools to enable analysis of how different energy end-uses contribute to total usage and operating costs.

How the actual total energy usage for the Keynes primaries compared with other similar recent new-build primary schools in the UK.

This comparative analysis was done on the basis of the standard benchmark metric for energy analysis - kWhr of total energy used in a 1 year period per m2 of GIFA for the school – this allows schools of different designs and sizes to be compared.

As the Sunesis Keynes and Keynes2 designs have ‘all electric’ building services (rather than the typical gas/electrical combination) these benchmark values were adjusted to give an equivalent value in kWhr of electrical usage as detailed in below.

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Oakfield 1FEY1

Oakfield 1FEY2

Arley1.5FEN Y1

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Ashcombe2FEN Y1

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St Annes1FEN Y1

Bemrose1.5FEN Y1

Kempston2FEN Y2*

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Design Actual

Conclusions

1. The actual usage was less than design target values in all cases, with an average of 18% less actual energy usage than design targets predicted over all 9 annual periods of operating data gathered.

2. This represents an average operating cost saving of c£2,800/year at current typical power costs (£0.10/kWhr) for each school.

3. Over the 60 year design life of each school, this would represent a total cost saving of c£165k and a total carbon emissions saving of 860 tonnes.

Total Energy Usage vs. Targets

The actual energy performance of the 5 schools compared to design target values is shown in Figure 1.

For 3 of the schools the actual data includes the first 2 years of operation following hand-over, which gives some idea of consistency of performance to date. The data included for Kempston Primary School is an estimate of total Year 2 usage based on 8 month actual + 4 months estimated from prior data on the previous season’s usage.

Figure 1 – Actual Usage vs Design Targets

Energy Usage Breakdown

The energy usage breakdown between the different end-uses is shown in Figure 2 below for 3 of the schools, expressing usage in kWhr/m2/year to more appropriately compare the different school models.

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Figure 2 – Energy Use Breakdowns By Type

Conclusions:

1. It can be seen that there is some reasonable degree of variation in usage between schools, and to some extent over time following seasonal changes and variations in usage pattern.

2. The degree of variation between schools in ‘non-regulated’ usage (ICT, power, kitchens and external lighting) is greater than the degree of variation in core building services usage from heating, hot water, auxiliary (pumps and fans) and internal lighting.

3. This is particularly true for kitchen usage and external lighting, perhaps the 2 end-uses with greatest project-to-project variation due to control settings and usage patterns by the school.

4. There is also some evidence for ‘economies of scale’ in energy usage being somewhat lower on a per m2 basis for the larger schools.

Total Energy Usage vs. Other School Benchmarks

The comparison of the Keynes and Keynes2 primaries with other similar new-build primaries in the UK is shown in Figures 3-5 below. The benchmark values used for comparison are taken from the following sources:

EFA1 benchmark

This is the target total energy consumption for new-build primary schools built under the Department of Education’s Education Funding Agency ‘Priority School Building Programme’ as published in 2013. The value used is for primary schools of an ‘all electric’ services strategy and includes all energy use categories.

EFA2 benchmark

This is the target total energy consumption for new-build primary schools built under the EFA’s Regional Construction Framework as published in the ‘Energy Efficiency Guide’ in June 2014. The value used is for primary schools of expressed in kWhr-electrical (converting gas/fuel use to electrical using a factor of 0.4) and includes all energy use categories apart from kitchen usage and external lighting.

DEC Typical benchmark

This is the energy usage of a ‘typical school’ of any age and type and is used as the basis for the Display Energy Certificate rating system in the UK. It is published by CIBSE as part of the TM46 Benchmarking Guide. The gas/fuel energy usage value was converted to electrical usage equivalent using the EFA factor of 0.4.

BPE Best/Average/Worst

These values are derived from the Building Performance Evaluation study commissioned by InnovateUK and published in January 2016. This study is perhaps the most definitive and independently verified evaluation of the performance of a wide range of non-domestic buildings built in the UK over the last 5 years.

The vast majority of the buildings selected and studied were to some extent ‘exemplars’ in their field, with considerable sustainability and low-energy credentials in most cases.

The benchmark values taken here were based on the best (lowest), average, and worst (highest) of the actual performance of the 6 primary schools studied in the BPE programme, with gas/fuel energy usage converted to electrical usage equivalent using the EFA factor of 0.4.

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Figure 3 – Keynes and Keynes2 Total Energy Usage vs. Benchmarks

Conclusions:

1. From Figure 3 we can see that the measured actual performance of all the Keynes and Keynes2 schools is below both the DEC benchmark, as might be expected, and also in almost all cases below the EFA1 benchmark for current new-build schools.

2. For the more recently constructed Keynes2 schools the actual usage is 10-15% below the EFA1 benchmark.

Notes:

The EFA2 benchmark excludes some important energy use categories as examined in Figure 4 on the following page:

Figure 4 - Sunesis Keynes and Keynes2 - Annual Energy Usage Totals(Totals exclude kitchen and external lighting usage as per EFA Target 2)

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In Figure 4 the total energy usage data for the 6 Keynes and Keynes2 schools has been corrected to remove the measured usage for kitchen equipment and external lighting, and is therefore directly comparable against the EFA2 benchmark for current new-build primaries.

Conclusions:

1. It can be seen that the Keynes and Keynes2 usage figures are also at or below the EFA2 benchmark in all but one of the 9 years of data.

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Figure 5 compares the Keynes and Keynes2 data with measured outcomes from the BPE primary school post-occupancy evaluation studies carried out on 6 primary schools across the UK.

As can be seen the range of performance across the BPE schools was quite significant with a factor of 4-5 in energy usage totals between the best and worst performing schools.

The average performance of the Keynes and Keynes2 schools was similar to the average performance of the BPE schools, which tends to suggest that Keynes and Keynes2 primary school energy performance compares favourably with outcomes measured across other schools with high sustainability and low-energy credentials.

3.0 Summary and ConclusionsEnergy performance monitoring studies, completed across 6 different Sunesis Keynes and Keynes2 primary schools over the last 3 years, have shown that the measured actual energy performance of schools:

1. Achieved better actual performance than design target values in all cases, with an average of 18% less actual energy usage than design targets predicted

2. Achieved similar or better performance that design target benchmarks set by the EFA for current new-build primary schools

3. Achieved similar performance, on average, compared to a range of independently studied UK primary schools with typically high sustainability and low-energy credentials.

Further monitoring studies are planned to continue through the future evolution of the Sunesis Keynes2 design to inform and support improvement in energy performance, operating cost and carbon emissions outcomes for education clients.

A better class of schoolSpirella 2Icknield WayLetchworth Garden CityHertfordshireSG6 4GY

www.sunesisbuild.co.uk@sunesis_schools