Institute Of Energy And Sustainable Development

Climate Change Adaptation Study

Report : St Pauls School, Leicester

January 2014

A.J. Wright Institute of Energy and Sustainable Development, De Montfort University

M.J. Taylor Miller Construction (UK) Ltd

Design for Future Climate: Adapting Buildings

Project ID: 1105_FS_LIB_DFFC2

Contents :

1.0 Section 1: Building Profile ………………………………………… ……………………..…1 6

1.1 Description…………………………………………………………………………………..18

1.2 Design Stage………………………………………………………………………………..21

1.3 Adaptation Study……………………………………………………………………………25

2.0 Section 2: Climate Risk Assessment………………… .. ………………………………….27

2.1 Datasets……………………………………………………………………………………..35

3.0 Section 3: Adaptation Strategy……………………………………… …………………….. 43

3.1 Simulation………………………………………………………………………………...…49

4.0 Section 4: Learning From Th is Report……………………………………………………. 68

5.0 Section 5: Extending Adaptation To Other Buildings………………………………….. 78

6.0 Section 6: Appendices………………………………………………………………………… 1

Appendix 1…………………………………………………………………………………………….3

Appendix 2…………………………………………………………………………………………...12

Appendix 3………………………………………………………………………………………...…16

Appendix 4…………………………………………………………………………………………...28

Executive Summary

This report details the results of the C limate Change Adaptation S tudy undertaken for St Pauls School, Leicester on behalf of the Technology Strategy Board ‘Design for Future Climate: Adapting Buildings’. It was revised in February 2013 following feedback from the Technology Strategy Board and again in April 2013 and November 2013 when Miller Construction (UK) Limited added additional project detail and technical, procedural, policy and financial content relevant to this and other similarly specified projects.

Initially the St Paul’s project was envisaged as being roughly 50% new build works and 50% refurbishment works, however on-going contractual developments have meant that the final design remit was for a primarily new build solution. Although these changes have led to delays in the overall project, they were necessary and unavoidable in order to achieve a mutually agreeable overall solution and it is these new build works that the Climate Change Adaptation Study is based on.

Following an initial review of the project specific information, topography and location, it was apparent that the main risk areas would be flooding during prolonged periods of heavy rain and overheating during the warmer summer months and at times of unseasonably hot weather. While the risk of flooding can be dealt with relatively simply through sensible drainage design and installation, and the careful adherence to the recommendations of a well-executed Flood Risk Assessment (FRA), adaptation to deal with overheating is more involved.

As the main body of this report will demonstrate, there needs to be a focus on reducing summer overheating, while also minimising the overall reliance on heating, fuel consumption and waste. This is best achieved by considering the problem sufficiently early in the design development process and implementing changes to the building fabric such as; increasing exposed thermal mass, incorporating greater thicknesses and more efficient insulation, and carefully exploring the options available in terms of glazing and shading selection. The results of the simulation have also been assessed in order to demonstrate the effect and influence that each variable might have on these overall problems.

Although each building and construction scheme has its own unique project dictates, this report demonstrates that other education schemes could also benefit by utilising similar design and construction drivers, established by the simulation and expanded upon in the textual analysis. Indeed it was Miller Construction (UK) Limited’s intention from the beginning of the process to use the results of this Report to generate a generic ‘Best Practice’ document that could be used to better inform its employees and ensure that all future projects benefited from enhanced sustainability, adaptability and robust design solutions.

It must be noted however, that different glazing areas/ ratios and building orientations etc may produce very different simulated results in other schemes and the findings of this report are purely theoretical until applied to a specific scenario with its own unique simulation and report.

Section One focuses on St Pauls School as a specific project and details the technical elements of the scheme including:

· Existing and new build elements

· An appraisal of the construction scheme Client Brief

· Specific project challenges and constraints

· The design process and the current stage in the overall design development

· An introduction into the Climate Change Adaptation Study, how it is facilitated and what end results can be expected from the exercise

Existing school siz e and characteristics Page 16

Relationship with the Krishna A vanti free-school Page 16

Pro ject challenges Pages 16-17

New build/ refurbishment split Page 17

Image of the exist i ng entrance building Page 18

Description of the existing school/ building(s) Pages 18-19

Occupancy pattern Pag e 19

Climat e heat gain factors Page 19

Existing topogra p hical survey drawing Page 19

Impac t of limited CAPEX Page 20

Image of proposed n ew entrance building Page 21

Project delays and the change from refurbis hment to new build works Pag e 21

Project milestones Pages 21-22

Focus of s imulation exercises Page 22

New build proposals Pages 22-23

Proposed site plan drawing Page 23

Landsca pe works proposals Page 23

Proposed refurbishment work s to existing boilers Page 23

Making good proposals Page 24

Collection of existing and new school buildings Page 24

Miller Construction (UK) Limited’s approac h to the Climate Change Page 25

Adaptation Study

Managing Client expectations against budget & current/ future climate Page 25

conditions

Design implications of the T hermal Model Analysis Page 26

Flood Risk Assessment, external levels desi gn, building location, Page 26

drainage design & SUDS principles

‘Best Practice’ guidelines and the need to constantly adapt in the futu re Page 26

Table of materials used in the external fa?ade Page 2 6

When determining a ‘high-level’ approach to this construction project it was necessary to assess all of the existing factors and variables and then select the most appropriate response. A summary of the key project information as determined by the Project Team is noted below:

· ‘Satisfactory’ or ‘Poor’ existing building stock that has been situated and designed as a direct result of the period of construction and site dictates

· Existing internal and external access issues

· Numerous existing changes in level

· Utilisation of a traditional materials pallet at present

· A current lack of innovation in terms of the materials and techniques utilised

· Ineffective existing natural ventilation system resulting in a significant problem with heating/ cooling and ventilation and no less than twenty-nine existing boilers

· Existing Classrooms that are too small and result in a shortfall in accommodation in line with the DCSF model school accommodation schedule

· At present the site suffers from flooding in times of heavy rain due to the flat orientation and poor existing drainage provision

· A limited CAPEX limits the extent of any construction works

· The budget allocation has been made primarily for the enhancement/ development of the building stock and not the external landscaping

· Project delays and a change in focus from refurbishment work to new build works has affected progress

In response to the factors noted above, the Project Team decided to develop a new stand-alone building with a similarly sympathetic pallet that would utilise modern technology, highly efficient and sizeable insulation elements to the floors, walls and roof; as well as ambitious U-Value and air leakage rate targets. The new building would be constructed across three-storeys to minimise the building footprint and maximise the amount of usable floor space. In order to address the fact that this would be the first building on site in excess of two-storeys, the second floor would utilise a change of materials and be stepped back to make it less obtrusive.

In order to address the inefficiencies of the existing M&E solution, Miller Construction (UK) Limited undertook to develop a solution that utilised natural, mixed-mode and mechanical ventilation principles in the respective areas where they were most suitable and in doing so effectively providing the right solution in the right area instead of an overall blanket ‘dictate’. Despite the limited refurbishment budget and scope, Miller Construction (UK) Limited will also amend the existing heating strategy across the retained estate so that new controls and an overall reduction in the amount of boilers can be realised and in doing so the aim is to improve campus efficiencies as a whole.

A large two-storey colonnade will be incorporated in order to add aesthetic interest as well as in response to the specialist’s Thermal Model analysis and will act as an integral part of the overall solar shading design solution. As part of the new design, external levels will be rationalised, level thresholds provided and flat access provided throughout the new ground floor so that there is no need for ramps or internal steps. As well as assisting with improved access for the disabled; the revised external levels will help to reduce the incidences of building flooding in the event of heavy rain, especially due to the fact that this approach will be coupled with improved drainage design and SUDS technology solutions.

In response to the requirements of the Climate Change Adaptation Study, Miller Construction (UK) Limited undertook to provide the theoretical aspect itself, while engaging De Montfort University to undertake the technical and analytical element on its behalf. The combined result was envisaged as a way of generating realistic recommendations that could be applied to future construction projects, (although they would not be used to directly influence the St Pauls School project). It is hoped that by doing this; short, medium and long-term design and construction strategies to better address climate change can be developed.

Section Two focuses specifically on the risk factors associated with this and other similarly specified construction projects. Micro and Macro factors are reviewed and applied to the St Paul’s scheme and the authors use this section to introduce some of the technical data streams used during the recording and collation of the data necessary to generate this report.

Risk Factors Page 27

Flooding Pages 27-31

Flood plain mapping image Page 27

HSP and the F lood Risk Assessment Page 28

Image of the existing schoo l entrance/ reception Page 28

Image of the existing schoo l entrance/ reception Page 29

Image of the ground slope towards the existing Sports Hall P age 29

Effect of the existi ng level differences Page 30

Discharge rate and the requirement for exten sive on-site attenuation Page 30

Ground conditions & inadequate maintenance ( drainage ditches silted Page 30

up or ‘re-claimed’ by neighbours)

Clay substrate - a poor drainage medium Page 30

2No images of existing drainage ditc hes in poor maintenance Page 30

Existin g drainage details Page 31

Poor belo w ground drainage Page 31

Future CCTV survey requirements Page 31

Heating & ve ntilation Pages 31-34

Building Regulations contribution t o overheating problems Page 31

Clima ctic data approach Page 31

Overheating due to user concentration, I.T , teaching practices & Page 31

personal user interface requirements

Climate cha nge characteristics Page 32

The need for more cool ing and less heating Page 32

Cooling/ ve ntilation strategy Page 32

Mi xed-mode solution Page 32

Mixed-mode image Page 32

Summer comfort Page 32

Heating Page 33

Overheating Page 33

Ventilation Page 34

Datasets & the description of t he Prometheus Project Pages 35-42

Datas et modelling table Page 35

Weather data Pages 35-36

Time period Page 36

Emission scenario Page 36

P robability Pages 37-38

IPCC climat e projections table Page 37

Emissi ons scenario table Page 39

Box & w hisker plots table Page 39

Box & w hisker plots table s Page 40

Box & w hisker plots table Page 41

Although the detailed determination of the project’s design principles is not detailed until Section 3 of this report, Section 2 went into greater detail with regards to the contributing factors that informed those decisions and these were assessed based on the following aspects:

· The greatest risk factors to the project are; flooding, overheating and inadequate ventilation

· A response to the current flooding issue was urgently required

· HSP’s Flood Risk Assessment suggests that the flooding is not being caused due to the site being in a high flood risk area, by proximity to other high flood risk areas, due to existing ground water issues, or due to overland flooding issues. Further to this, as the PPS 25 document states that the type of development being proposed is suitable for this type of site, the cause of the flooding must be something else

· The ground floor level of the existing reception/ main entrance building is significantly lower than that of the neighbouring car park etc. As well as this, the existing strip drain is ineffective and does not act as a barrier to flood water running off the impervious car park medium

· Clearly the existing level differences have a negative effect on surface water ingress into the main entrance/ reception building

· There are large areas of existing impervious material and when coupled with a permissible off-site surface water discharge rate of 16l/s this makes adequate management of surface water run-off difficult

· Poor maintenance of the existing drainage ditches exacerbates this issue

· Existing ground conditions indicate the presence of a clay substrate which is a poor drainage medium and effectively rule out soakaways and infiltration principles as permissible options

· Initial investigations/ enquiries suggest that the existing below ground drainage installation is in poor condition and this manifests itself by backing up and flooding the existing school

· The Building Regulations actually contribute to overheating and inadequate ventilation design in modern buildings

· In modern building overheating is experienced due to user concentrations, I.T requirements, increasing reliance on technological solutions, developed teaching practices and personal user interface requirements

· Current climate change characteristics as well as the predicted trend suggest that this will be further exacerbated

Having assessed the findings noted above, the Project Team decided to address the issues as two aspects; i) flooding and ii) overheating/ ventilation. Details of the design principles adopted have been included within Section 3 of this report, although it is clear from the Section 2 analysis that external ground levels would need to be addressed and that in order to address the issue of surface water run-off, considerable on-site attenuation provision would be required. It was also decided that in order to fully appreciate the condition of the existing below ground drainage installation, a comprehensive CCTV survey would be required.

In order to address the overheating/ ventilation issues fully, the Project Team decided to engage De Montfort University and make use of the datasets and the Prometheus Project information in terms of current and future climate conditions. Again, more detailed design principles have been included in Section 3 of this report, although it was clear that the Team would need to focus its design concept on increased cooling requirements and minimal heating requirements. It was generally agreed that one way of doing this effectively, efficiently and in line with the project cost plan was through the introduction of mixed-mode technology.