Beyond Zero

Carbon HousingCarbon Housinge x p l o r i n g s o l u t i o n s t o s u s t a i n a b i l i t y i s s u e s

b e y o n d t h e z e r o c a r b o n a g e n d a

2 4 t h O c t o b e r 2 0 1 2 a t T h e U n i v e r s i t y o f N o t t i n g h a m2 4 t h O c t o b e r 2 0 1 2 a t T h e U n i v e r s i t y o f N o t t i n g h a m

D e p a r t m e n t o f A r c h i t e c t u r e a n d B u i l t E n v i r o n m e n t

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The Challenge of The Challenge of DeliveringDelivering

Green Street Green Street NottinghamNottingham

Energy Efficient Housing for Market Energy Efficient Housing for Market SaleSale

Peter Conboy, Blueprint

Green Street Green Street NottinghamNottingham

Green Street Green Street –– Project ContextProject Context

• Former primary school site owned by NCCFormer primary school site owned by NCC

•• Close to the River Trent and riverside Memorial Gardens;Close to the River Trent and riverside Memorial Gardens;•• Close to the River Trent and riverside Memorial Gardens;Close to the River Trent and riverside Memorial Gardens;

•• Adjoins the Meadows priority housing regeneration area;Adjoins the Meadows priority housing regeneration area;

•• NCC ambition to raise housing quality standards and sales NCC ambition to raise housing quality standards and sales valuesvalues

•• Use this to enhance viability and delivery for wider scale Use this to enhance viability and delivery for wider scale housing regeneration in Meadowshousing regeneration in Meadows

•• Market crash in 2008 caused some delay and renegotiation of Market crash in 2008 caused some delay and renegotiation of

Green Street

•• Market crash in 2008 caused some delay and renegotiation of Market crash in 2008 caused some delay and renegotiation of termsterms

•• Planning approval secured 2009 and start on site Jan 2010Planning approval secured 2009 and start on site Jan 2010

Green Street Green Street -- Scheme Scheme DescriptionDescription

•• 38 No. Family Houses in a mix of 3 and 4 bed;38 No. Family Houses in a mix of 3 and 4 bed;

•• 15 no. of the homes are low15 no. of the homes are low--cost home ownership (shared cost home ownership (shared •• 15 no. of the homes are low15 no. of the homes are low--cost home ownership (shared cost home ownership (shared equity);equity);

•• Code for sustainable homes level 4;Code for sustainable homes level 4;

•• EPC A or high B depending on roof space for PV panels;EPC A or high B depending on roof space for PV panels;

•• Fabric first approach Fabric first approach -- highly insulated and airhighly insulated and air--tight structural tight structural solution with mechanical ventilation and heat recovery;solution with mechanical ventilation and heat recovery;

•• Scheme completed in July 2012 and is fully occupied.Scheme completed in July 2012 and is fully occupied.

Green Street

•• Scheme completed in July 2012 and is fully occupied.Scheme completed in July 2012 and is fully occupied.

Site Location

Ground Floor First Floor Second Floor

First Floor Second Floor

Ground Floor

First Floor Second Floor

First Floor Second Floor

Ground Floor

First Floor Second Floor

Ground Floor

First Floor Second Floor

Ground Floor

Green st Costs

•• Total building contract value £5.5 millionTotal building contract value £5.5 million

•• JCT 2005 Design and BuildJCT 2005 Design and Build•• JCT 2005 Design and BuildJCT 2005 Design and Build

•• Headline cost Headline cost -- £125 £125 psfpsf

•• Excluding PV and flood Excluding PV and flood abnormalsabnormals -- £110 psf.£110 psf.

•• Average sales Average sales vvalues £158 alues £158 psfpsf

•• Meadows average values circa £135spfMeadows average values circa £135spf•• Meadows average values circa £135spfMeadows average values circa £135spf

•• Peak value achieved at Green Street £174 Peak value achieved at Green Street £174 psfpsf ––3 bed £186k and 4 bed £230k3 bed £186k and 4 bed £230k

Green St Green St –– Fabric Design Fabric Design PerformancePerformance

•• Considered Passivhaus at planning stageConsidered Passivhaus at planning stage

•• Timescale for grant expenditure very tight and delivery risk Timescale for grant expenditure very tight and delivery risk •• Timescale for grant expenditure very tight and delivery risk Timescale for grant expenditure very tight and delivery risk considered too greatconsidered too great

•• Fabric first approach plus efficient condensing boilers and heat Fabric first approach plus efficient condensing boilers and heat recovery.recovery.

ElementElement uu--Value / Value / w(m2.k)w(m2.k)

2013 Build 2013 Build RegsRegs FEESFEES

1960s1960s

External

Walls

0.13 0.18 1.7

Walls

Roof 0.11 0.13 1.42

Floor 0.15 0.13 N/A

Windows

/ doors

1.20 1.40 5.7

Green St – Other Features

•• Solar PV array Solar PV array –– typically 1.4 to 1.6 kW peak to typically 1.4 to 1.6 kW peak to •• Solar PV array Solar PV array –– typically 1.4 to 1.6 kW peak to typically 1.4 to 1.6 kW peak to achieve EPC A rating overall;achieve EPC A rating overall;

•• Phase 1 of Green Street Phase 1 of Green Street –– timber frame, phases timber frame, phases 2 and 3 traditional masonry construction;2 and 3 traditional masonry construction;

•• External blinds to prevent overheating in phase External blinds to prevent overheating in phase 1111

•• Phases 2 and 3 internal wet plastered masonry Phases 2 and 3 internal wet plastered masonry walls to enhance thermal mass;walls to enhance thermal mass;

Actual v Design Performance

DEVIL DEVIL Ψ IS IN THE DETAILINGIS IN THE DETAILING

••Blueprint working with Nottm University to test actual thermal Blueprint working with Nottm University to test actual thermal ••Blueprint working with Nottm University to test actual thermal Blueprint working with Nottm University to test actual thermal performance of occupied homes via the TSB studyperformance of occupied homes via the TSB study

••Design air permeability for Green Street Design air permeability for Green Street -- 3 cu metres per hr / sq 3 cu metres per hr / sq metre at 50 pascal;metre at 50 pascal;

••2013 Building Regs suggestion 2013 Building Regs suggestion -- 5 cu. metres per hour / sq metres?5 cu. metres per hour / sq metres?

••Previous testing regime requires only a sample of homes within a Previous testing regime requires only a sample of homes within a scheme to be tested;scheme to be tested;

••Some homes can perform significantly worse than the design level Some homes can perform significantly worse than the design level ••Some homes can perform significantly worse than the design level Some homes can perform significantly worse than the design level which means energy efficiency is way off target which means energy efficiency is way off target –– a 1 mm gap 1 metre a 1 mm gap 1 metre long changes the 1 sq metres ulong changes the 1 sq metres u--value from 0.3 to 1.44value from 0.3 to 1.44

••To deliver very air tight homes need both careful detailing of fabric To deliver very air tight homes need both careful detailing of fabric design and monitoring on site to ensure workmanship is up to scratch design and monitoring on site to ensure workmanship is up to scratch –– with additional costs resulting?with additional costs resulting?

Actual v Design Performance

DEVIL DEVIL Ψ IS IN THE DETAILING IS IN THE DETAILING

••As dwellings become better insulated (fabric uAs dwellings become better insulated (fabric u--values fall) the relative values fall) the relative ••As dwellings become better insulated (fabric uAs dwellings become better insulated (fabric u--values fall) the relative values fall) the relative importance of thermal bridging in conduction heat loss increases importance of thermal bridging in conduction heat loss increases ––could account for 30% of heat loss post 2013;could account for 30% of heat loss post 2013;

Actual v Design Performance

SOME KEY QUESTIONSSOME KEY QUESTIONS

••Research shows actual energy performance from 10% to 120% worse Research shows actual energy performance from 10% to 120% worse ••Research shows actual energy performance from 10% to 120% worse Research shows actual energy performance from 10% to 120% worse than predicted design performance with the average (in the research) than predicted design performance with the average (in the research) at circa 40%at circa 40%

••How can the gap between actual and design performance be closed How can the gap between actual and design performance be closed effectively and at an affordable cost?effectively and at an affordable cost?

••Can housebuilding industry supplyCan housebuilding industry supply--chains actually deliver the higher chains actually deliver the higher performing homes required in the numbers that are required performing homes required in the numbers that are required –– circa circa 200k homes per annum?200k homes per annum?200k homes per annum?200k homes per annum?

••Are the skill levels present in the house building industry at present to Are the skill levels present in the house building industry at present to build energy efficient homes that actually perform as designed?build energy efficient homes that actually perform as designed?

••How can quality control and inspection be managed on site across How can quality control and inspection be managed on site across large scale developments?large scale developments?