1

Moving towards low-carbon buildings: New-build and Existing stock

Dr Rajat Gupta, Conference Chairrgupta@brookes.ac.uk

Urban sustainability and Green buildings for the 21st century15 May 2009, Delhi

• Background: cities, buildings and carbon emissions.– Energy efficiency versus carbon intensity: low and zero carbon buildings.– Legislation and standards for reducing the carbon footprint of new and existing

buildings: key priorities.• Our research on carbon-counting and carbon-reduction

– Oxford Solar initiative– DECoRuM® model: carbon mapping of dwellings on an urban scale– Oxford Climate Change Action Plan– World Bank project – decarbonising national building stocks– Post-occupancy building evaluation

• Final words…

Structure of presentation

2

Background: Cities, buildings and carbon emissions

For millennia, we have lived in

passive buildings

3

Source: Herbert Giroudet

X CONSUMPTION =

Eugene 16th April 2007

PEOPLE

4

On top of that we are running out of oil and gas

Cities, CO2 emissions, and urbanisation• Half the global population

lives in cities: three-quarters of the human population to become city dwellers by 2050.

• Cities account for 75% of total global energy demand and produce 80% of our CO2emissions driving climate change.

00.5

11.5

22.5

33.5

44.5

1950 1975 2000 2015 2030

pop

ulat

ion

in b

illion

s

developing countries - urban developing countries - rural

developed countries - urban developed countries - rural

http://www.infoforhealth.org/pr

5

In 2002, buildings were responsible for 7.85Gt, or 33% of all energy-related CO2 emissions worldwide.

Impact of climate change: AdaptationPossible increases in the intensity of tropical storms or in the intensity of heavy rainfall events will directly impact buildings.

Heating energy use will decrease, the demand for cooling will increase.

Many passive and low-energy techniques for cooling buildings (evaporative cooling, or night ventilation) may become less effective as heat waves become more intense and longer-lasting.

Climate change and the Building stock

Energy use in buildings and CO2 emissions: Mitigation

Energy use in buildings will grow by 34% in the next 20 years, at an average rate of 1.5% (EIA, 2006).

Buildings’ energy consumption outlook

6

Direct (on-site): Emissions from fuels combustion (space heating)

Off-site: Emissions from public electricity use and district heat consumption.

Globally, the building sector is responsible for 42% of electricity consumption more than any other sector.

CO2 emissions from building energy use

UK

UK CO2 emissions by sector, 2002

CO2 emissions by sector in UK, USA and India

USA India

Industrial buildings

5%

Domestic buildings

26%

Agriculture1%

Transport33%

Industrial process22%

Commercial and public buildings

13%

USA CO2 emissions by sector, 2005

Agriculture31%

Industrial36%

Commercial7%

Residential23%

Transportation3%

Electricity use by sector, 2005

45% 48% 30%

7

Key principles: low and zero carbon buildings

Oxford Institute for Sustainable Development: Architecture

Low-carbon buildings result from the: - Careful design of the building form and construction

to reduce energy demand.- Combined with highly-efficient heating and cooling

systems.- Energy-efficient appliances - Reduction of the carbon intensity of energy input by:

- Low carbon technologies such as: heat pumps, micro-CHP

- Renewable energy technologies: solar PV, solar thermal, wind

- Near-site renewables.- Subtle human control systems that empower

occupants to become part of the building energy operation systems.

What is a low carbon building?

8

Low-carbon, carbon-neutral and zero-carbon buildings

• Low carbon: achieve at least a 50% reduction in emissions (with regard to energy use in buildings) over current building regulations.

• Carbon neutral buildings: Zero net emissions from all energy uses within the building, by importing offsite generated renewable energy from the grid or via private wires.

• Net zero carbon: Carbon-emitting fuels are burnt on site, but locally-generated renewable energy is exported to the grid to make up for this.

• Zero carbon: No carbon-emitting fuels are burnt on site and no electricity is imported from the grid.

Source: BRE and DCLG

LIFEYCLE ENERGY USE, NEW HOUSE

Embodied energy

Elec. for lighting and appliances

Gas for heating and cooking

30%

66%

4%

NOTE: For a 160m2 detached house built to Part L of the 2002 Building Regulations and assuming that energy use for space heating matches the design predictions. Calculated over a lifecycle of 100 years.

Life cycle energy use in a typical new house

9

Legislation and Policy drivers for low carbon buildings:

Case of UK and USA

UK’s 2050 targetUnder the Climate Change Bill, UK Government required to cut CO2 emissions to 80% below 1990 levels by 2050 (Increased from 60%)

UK Renewable energy target 202015% of UK energy be sourced from renewables by 2020.

Critical to meeting the UK’s renewable energy targets will be the widespread deployment of micro-generation installations in housing.

National Energy Efficiency Action Plan – sets a target to reduce emissions from the UK’s housing stock by 31% on 1990 levels by 2020.

2020 target

CO2 and renewable energy Targets for UK housing

10

More recent - DECC - Whole House approach

• Consultation on the Government’s Heat and Energy Saving Strategy sets out an aim for emissions from existing buildings to be approaching zero by 2050 (80% target).

• All homes to have received by 2030 a ‘whole house’ package including all cost-effective energy saving measures, plus renewable heat and electricity measures as appropriate.

• Aim to help some 7 million homes to take up these changes by 2020.

• Introducing energy performance certificates (EPCs) when buildings are let, sold, built or refubished.

• Requiring public buildings to display energy certificates (DECs); and

• Requiring inspections for air conditioning systems.

EU Directive of Building Energy Performance (EPBD)

11

It is within this context that our research is undertaken…

Some examples of our research

12

Objectives

- Create Targets: 10% of all houses in Oxford to have solar systems by the year 2010

- Capacity build the local government to reduce CO2emissions.

- Establish strategic alliances to make these reductions happen.

- Initiate and implement a solar campaign.

To find the best ways to introduce solar energy technologies (SET) and the rational use of energy (RUE) in Oxford.

So far OSI has facilitated the installation of 100active solar systems, over 450 energy efficiency measures and 3,000 low energy light bulbs (CFLs).

Developed an Oxford Solar Map.

Oxford Solar Initiative: Implementation phase

13

DECoRuM®: A GIS-based carbon-counting model

www.decorum-model.org.uk

© Rajat Gupta 2006

DECoRuM energy & CO2 model: Bottom-up carbon counting

14

Oxford Climate Change Action Plan

(OCCAP)

Decarbonising National Building stocks: measurement, strategies,

and benchmarks

15

Per-capita energy use and CO2 emissions

7,920

3,906

531

6,206kWh

13,351kWh

457kWh

9.4t

19.9t

1.2t

02,0004,0006,0008,000

10,00012,00014,00016,000

UK USA India0

5

10

15

20

25Energy use per capita (kg oil equivalent)

Electric power consumption per capita (kWh)

CO2 emissions per capita (metric tons)

(Source: The World Bank Data Book, 2007)

Building energy use in UK, USA and India

National benchmarking databases Criteria

BERR DOE

Individual study estimates*

Dwellings UK (2007) USA (2005) India

Total number of households 26.142 million 111.10 million Data unavailable

Energy use per unit area 228 kWh/m2/yr 138 kWh/m2/yr Data unavailable

Energy use per household 19,851 kWh/house/yr 27,815 kWh/house/yr Data unavailable

Non-domestic UK (2005) USA (2003) India

Energy per unit area 262.1 kWh/m2/yr 287.2 kWh/m2/yr 189 kWh/m2/yr

16

Comparison of environmental rating systems: UK, USA, India

CO2 emissions from Type 0 Solar Offices can be over 90% less from a typical Type 4 Office –even less with green tariff power.

UK: CO2 Indices for typical, good practice and zero emission buildings (Adapted from: ECON 19)

17

Ener

gy C

onsu

mptio

n for

Coo

ling (

kWh/m

2/y)

300Si

ngle

Glaz

ed T

ower

(70’s

)

210Do

uble

Glaz

ed T

ower

(90’s

)

50Ins

ulated

S.G

. (80

’s)

40

Insula

ted S

D.G.

(90

’s)

15

Low

Ener

gy D

esign

. (90

’s)

5

Pass

ive O

ffice.

(90’s

)

Energy consumption for Cooling: Offices

(Source: Professor Mat Santamouris, University of Athens, 2007)

Post-occupancy building evaluation: evidence-based performance

18

POE of sustainable education and healthcare buildings: feedback to inform future building designCommissioned by Architects to undertake POE of 8 sustainable buildings.

Provides valuable feedback to both architectural and building services firms to inform their subsequent building designs, specifications and performance.

And finally…

19

Tough choices have to be made!!!!

20

ZEH, Sacramento

Humanity Forward

Low and zero carbon buildings: a reality:

living on the planet as if we intended to stay

Thank you!