Achieving Low Carbon Buildings - Design and Procurement

ProcessesDr Andrew Platten

Associate Dean, Leeds Metropolitan UniversityChair Centre for Urban and Built Environment

What is procurement ?

• About finding a service for the client• At the right quality• Right time• Right price• ….and making the client feel good

What is low carbon ?

• Energy efficiency• Renewable energy sources• Low environmental impact• Zero waste• Sustainable materials• Reuse ?• Adaptability for the future ?

Introduction• The need for affordable and energy efficient homes• A commitment for zero carbon new build by 2016 now 2019• Home design led by the Code for Sustainable Homes (CSH),

complementing the introduction of Energy Performance Certificates in 2007

• Part L of the Building regulations which is leading to ongoing changes in thermal performance and the adoption of low carbon design

• Best practice in procurement and process for 16 years• Effect linking all parties in the design and production process, clients

and contractors to achieve efficiency and improvement in the industry• Public sector has acted as the exemplar for change• BSF / NHS LIFT / HMR legacy

Design Standards

International Green Standards

• BREEAM with 12 different guides for buildings

• Passiv Haus• Leadership in Energy and Environmental

Design• China Three Star• Green Star – Australia• Estidama Pearl Rating System

CSH Design Categories

• energy usage and CO2 emissions, • pollution, • water usage, • standards for health and well-being, • the adoption of low impact and energy reducing materials, • standards for management on site, • the management of surface water run-off , • the protection of ecology and • waste minimisation

CSH

Code Level

Standard (Percentage better than Part L)

Points Awarded

Standard (litres per person per day)

Points awarded

Other points required

1 10 1.2 120 1.5 33.3

2 18 3.5 120 1.5 43.0

3 25 5.8 105 4.5 46.7

4 44 9.4 105 4.5 54.1

5 100 16.4 80 7.5 60.1

6 A zero carbon home

17.6 80 7.5 64.9

Low or Zero Carbon Technologies (LZC)• Not mandatory to the CSH, but credit awarded for • 10% reduction in carbon emissions as a result of

supply from a renewable source (1 credit), or• 15% reduction in carbon emissions (2 credits)• CSH controls include:

– accredited external renewable sources / biomass such as burning, gasification or anaerobic digestion,

– ESCO (an Energy Services Company), – Renewables including: solar including solar thermal

and photovoltaics, small scale hydro power, wind turbines, CHP or heat pump technology

BREEAM – Multi-residential

• Design Stage (DS)– leading to an Interim BREEAM Certificate

• Post-Construction Stage (PCS) – leading to a Final BREEAM Certificate– post-construction review of an interim design-

stage assessment– post-construction assessment

BREEAM Scoring System

Classification Score

UNCLASSIFIED <30

PASS ≥30

GOOD ≥45

V GOOD ≥55

EXCELLENT ≥70

OUTSTANDING* ≥85

BREEAM Environmental WeightingsBREEAM Section Weighting (%)

Management 12

Health & Wellbeing 15

Energy 19

Transport 8

Water 6

Materials 12.5

Waste 7.5

Land Use & Ecology 10

Pollution 10Minimum standards set for each section and additional credits awarded for innovation

Management: Credits awarded for planning, design meetings, on site control and user information

Energy: Credit awarded for CO2 emission reduction, sub-metering, lighting, LZC technologies, white goods, CHP, drying space.

Procurement

The Supply Chain

• Getting it right, cost, time and quality• Procurement encouraged to achieve best public benefit• Education, housing and health sectors placed wider criteria in

selection processes• Public sector led innovation eg CSR. Low carbon, local benefit to the

regions• First tier companies placed with the responsibility to develop their

supply chains – public sector frameworks such as Yorbuild / GM Procure / Efficiency North

• The reality of public sector intervention to aid development• RDA support in the regional sectors to end 2011• Post 2011 regional growth with private sector support ?• Private sector financers now using development as a guarantee of

quality

Egan’s Regeneration Skills

• Environmental• Economic • Socio-cultural• Governance• Transportation • Quality of services to the public • The quality of the built environment

Effectively, public sector clients need to emphasise these criteria in developer and contractor selection processes, for example employment, carbon reduction or efficiency gains

Partnering Process

• Seen as a means to achieve change and innovation

• Both internal and external to client organisations• Transparency of process• Appointing a partnering team• Developing team members ready for

collaboration• Common aims and processes• Performance measurement

Housing Market Actions

• Long term shortage of supply in the UK which has kept prices high

• Affordability issues• Subject to huge change in the past 9 months• Pre-June 2010 • Sustainable Communities: Homes for All

launched a huge upgrading process for existing homes (Decent Homes), HIPS investment in stock management and Pathfinder

Case Study: Pathfinder

• The East Lancashire pathfinder Elevate established four new build developments adopting the partnership model and selected developer / contractors using environmental criteria in addition to wider performance and economic indicators

• Key performance indicators (KPI) were developed to measure the performance of the developers

• KPI were used to determine a proportion of the developer return

Elevate KPIs

• Incentivised– Code for Sustainable Homes– Design quality– Implementation of Phase

Milestones– Local Labour– Local Suppliers– Quality– Good Constructor Practices– Predictability of Construction– Training– Health and Safety– Good Developer Practices– Developer Satisfaction

• Not Incentivised– Community Satisfaction– Partnering Relationships– Supply Chain Satisfaction– Sustainable Development– Land Registry Property Prices– Demographic Change– Local Health Statistics– Crime Statistics

Blackburn Waterside

• Two year programme• RSL with regional

contractor• £14,390,000 value• 131 units• Mixed tenure• Brown field site• Timber frame system

Blackburn Waterside

• Features included:– Air tightness– Efficient boilers for heating and

hot water– Mechanical extract and heat

recovery

• Low cost housing £60k to 160k• CSH code 3 minimum• Thermal performance• Passive approach

Blackburn Waterside

• Use of timber framed construction to achieve low U value, built by an accredited supplier

• Local labour maximised for other elements

• Training plan monitored• Monthly progress

recording

Post 2010

• Government investment curtailed• The low carbon agenda has changed• DECC LCBP closed• The Green Deal: home improvement paid for via energy bills due

Spring 2012• RSLs in a tight corner• District authorities with some movement for now, BREEAM Excellent

is a planning requirement in some areas• Efficiency / cost accuracy top priority• Learning the building science• Zero carbon the home of the committed client ? The Good Homes

Alliance, the Green Building Store, etc

Case Study: STAMFORD BROOK

• Evaluating the Impact of an Enhanced Energy Performance Standard on Load-bearing Masonry Domestic Construction Partners in Innovation CI 39/3/663 - BD2324

• Stamford Brook is a development of around 700 dwellings constructed on part of the Dunham Massey Estate near Altrincham in Cheshire.

Background

• Construction period 2004 - 2010. • A partnership agreement between the land

owner, the National Trust, Redrow and Bryant Homes.

• A “Partners in Innovation” (PII) project with the CeBE at Leeds Metropolitan University (Leeds Met) that has investigated various aspects of the design and construction processes.

Project Objectives

• The overall PII project objective was to support future reviews of Part L of the Building Regulations

• Evaluation of the various impacts on a large scale masonry housing development of a range of improvement measures that could be used to meet the requirements of an advanced energy performance standard

• The impacts and issues that the project was designed to assess included the following:– Technical Impact– Economic Impact– Regulatory Issues– Design Process Issues– Site Project Management and Construction Process Issues– In-use Performance

The EPS08 Energy Standard used at Stamford Brook

• The EPS08 standard was a prototype energy standard for the St Nicholas Court project with the intention that it would inform the revision of the Building Regulations that was expected at the time to occur in 2008.

• The EPS08 standard defines elemental target U-values for the main construction elements, a maximum limit for air permeability and a limit on the carbon intensity of the heating system.

• The equivalent carbon emission rate for an EPS08 compliant dwelling would be around 10% to 15% better than that required under Part L1a 2006, depending upon dwelling form and size.

EPS08 Prototype Performance Energy Standard Requirements

Element EPS08

Exposed walls U value 0.25 W/m2K

Roof U value 0.16 W/m2K

Floor U value 0.22 W/m2K

Windows, doors and roof lights

U value 1.30 W/m2K. Max area 25% of gross floor

Air permeability 5 m3/h at 50Pa

Carbon intensity of heating system

70 kg CO2/GJ useful heat – min gas condensing boiler efficiency of 85%

Min Air Supply Ventilation Standards

Min Air Supply Requirements Min Air Extract Requirements

Double bed 10 l/s Kitchen 20 l/s

Single bed 5 l/s Bathroom 10 l/s

Living Room 5 l/s Separate W/C 10 l/s

Dining room 5 l/s

Other 5 l/s

The “build tight – ventilate right” concept has been promoted since the eighties; the current Approved Document L for England and Wales sets the air permeability target for new dwellings at 10m3/hm2 at 50Pa. Reducing air permeability – in other words, uncontrolled air leakage – is a cost-effective means to improve energy efficiency. Indeed, the Passivhaus house standard requires an air permeability index of 1m3/hm2 at 50Pa.

Project Findings

• Party wall thermal by pass: Experiments undertaken at Stamford Brook have shown that heat loss via party wall cavities in masonry dwellings can be significant.

• The party wall thermal bypasses will be present in most new masonry dwellings with cavity party walls

• Measurements have shown that the party walls at Stamford Brook have an effective U-value of around 0.5 W/m2K to 0.7 W/m2K.

• Analysis of the experimental data has shown that the mechanism for heat loss via the party wall is driven by upwards air movement in the cavity.

• Heat is then lost via the loft space.

Airtightness

• The design adopted (cavity masonry construction) is perfectly capable of delivering the specified target air permeability of 5 m3/(h.m2) @ 50 Pa

• The airtightness work at Stamford Brook has demonstrated that the technology used, parged masonry walls linked to airtight top floor ceilings and ground floors, can deliver airtightness that is below 2 m3/(h.m2) @ 50Pa.

• The difficulties encountered were process related:– incomplete design information– insufficient attention to detailed sequencing of operations, that

were not systematic in their control of quality and did not provide consistent feedback to improve design and construction practices.

Zero Carbon – Passiv Haus

Reducing Carbon – Passivhaus• External shell - U-Value that does not exceed

0.15 W/m2/K Limiting U-values of approximately 0.25-0.35 W/m2/K

• Passive use of solar energy is a significant factor in PassivHaus design.

• Windows should have U-values not exceeding 0.80 W/m².K  for both glazing and frames - this requires the window frame to incorporate insulation and the glazing to be triple.

Passivhaus

• Air leakage (n50) through unwanted gaps and cracks in the building fabric must be less than 0.6 times the house volume per hour under negative and positive pressurisation.

• Design air permeability of 7 to 10 m2/hr/m3@ 50 Pa. This is approximately a factor of 10 poorer than the PassivHaus standard.

• Pre-heating incoming air• Mechanical or passive stack air ventilation• Heat exchange for vented air at 80% efficiency

Passivhaus

• Energy-saving household appliances: Low energy refrigerators, stoves, freezers, lamps, washers, dryers, etc. are indispensable in a PassivHaus.

• Dedicated low-energy lights are provided in a number of rooms in a new dwelling.

• Total energy demand for space heating and cooling less than 15 kWh/m2/yr Typically 55 kWh/m2/yr 1

Case Study: Carnegie Village: Leeds Metropolitan University• 479 study bedrooms in ‘cluster

flat’ and ‘townhouse’ arrangements, 10,275m2.

• BREEAM Excellent, 76.1%• Low energy installations • High levels of insulation • High levels of airtightness• Mechanical heat recovery

ventilation systems • Low Nox, A-rated gas condensing

boilers Solar water heating

Passivhaus 12 bed units

Key design features include• Building management system• Low water use aerated taps and showers,

dual flush WCs - SUDS (sustainable drainage system) wastewater attenuation system

• Full, low energy lighting /passive infrared (PIR) to common areas

• High levels of acoustic performance• Dimensioning to accommodate standard

building material sizes• Simple plan configuration• Use of A-rated Green Guide products FSC-

certified timber• In passivhaus design internal heating

elliminated

Passivhaus

• Two door entry to enclose warm air

Case Study: Denby Dale Passiv Haus• The Green Building Store• First UK Passivhaus to be built with cavity

wall construction.• One of the first certified Passivhaus homes

in the UK• Minimal heating - using 90% less energy

for space heating than the UK average• £141K basic build costs• 118m2 three-bed detached house

Windows and Openings

• Ecopassiv timber windows that are triple glazed and have a whole-window U-value of just under 0.8W/m2K (and glazing U-value of 0.6W/m2K).

• Low-emissivity coatings and argon fill

• Windows for Passivhaus-level projects usually have to have some insulation in the frame (in this case polyurethane).

Thermal barrier – 300mm

MVHR

• Mechanical ventilation and heat recovery

• Air supply to dry areas and vented from wet areas

• Heat is extracted from outgoing air and used to heat the incoming air saving 90% of heat

• Economic at air tightness less than 3 air changes per hour @50 Pa

Air tightness

Final figures

Airtightness: 0.33 ach @50 Pa measured using the Euronorm and Passivhaus method

Passivhaus requirements are 0.6 ach @ 50 Pa

Denby Dale Passivhaus

What of Procurement ?• The framework is here to stay• Accuracy of cost estimates and savings taking priority but still targets

set for CSR and sustainability will often gain planning approval and this will remain part of the picture

• Thus the PQQ and Performance management are the art of procurement

• Issues are in meeting design standards and conveying them in procurement documentation

• Evidence of performance on site and project performance will be the credentials for continued engagement

• But how we use procurement to achieve zero carbon is one of education and commitment of all parties

• Technical quality and on site standards will be critical to high performance dwellings in the lead up to 2019

• Training standards and supervision remain important

Post Script

• What did we learn from the boom period ?• What can we do in the next ten years that will make a

difference– Energy– Public / private balance– Politics– Environment– Efficiency– Technical accuracy– Excellence management

Thank you