16469 Low Energy Building Design Sustainability – an overview

Dr Nick Kelly

ESRU

This Class

• the basis of this class are the principles of sustainability

• but what are these?

Class Activity

• in the context of buildings what does sustainability mean to you?

• get into a group of 4 and produce 5 bullet points that encapsulate your understanding of a sustainable building

Sustainability in Buildings“Sustainable building design should aim to provide a balanced solution, offering optimum working/living conditions, alongside reduced environmental impact, both now and in the future. Taking the complete building lifecycle into consideration, there are many factors involved, from the location of the building, its design, subsequent operation and maintenance, to the construction materials and practices used, and how any future changes of use are addressed.”

D. McLean (IET)

Origins of Sustainability

• Stockholm agreement (1972) addressed environment, economic and social development and outlined 26 principles for sustainable development .

• Brundtland Report (1987) defined Sustainability as:

"Sustainable development is development that meets the needs of the present without

compromising the ability of future generations to meet their own needs"

Origins of Sustainability

"Sustainable development is development that meets the needs of the present without

compromising the ability of future generations to meet their own needs“

• as Engineers and Architects how does this apply to our activities?

UK Implementation

• The UK government has published its guiding principles with regards to sustainability

• http://www.sustainable-development.gov.uk• Covers much more than just energy and

natural environment– economy and employment– social justice– communities– etc.

UK Implementation1

2 3

4

UK Priorities

• FOUR key areas: – sustainable consumption and

production [1,2]– climate change and energy [1,2]– natural resources [1]– sustainable communities [4]

• ALL of these areas relate to the built environment

Consumption• the built environment is the largest final energy consumer • in the built environment 40%3 of the energy consumed is used

is for space heating with most heating systems running on natural gas

• overall energy consumption is on the increase with a 19% rise in the domestic sector and 17% rise in the services sector since 19903 driven by: – demographics (increasing # of households 18.6M – 24.2M

1971-20054)– comfort expectations (average internal temperatures have

risen 5oC since 19705)– lifestyle (multi-source lighting, increasing use of electrical

appliances)• sustainability necessitates controlling energy demand

without compromising on comfort and health

Sources 1 DUKES 2005, 2 NS Social trends 3 Energy consumption in the UK 4 NS Social trends, 5 domestic energy fact file 2001

Production• the domestic sector alone accounts for 28%1 of final

energy consumption and 42 million tonnes of carbon (MtC) per annum2

• UK-wide buildings accounting for over 40% of all UK carbon dioxide emissions, and with as many as 140,000 new homes needed each year it is no surprise that reducing these emissions is currently a key focus

• improving energy efficiency has been identified as being the cheapest, cleanest and safest way of doing this

• renewables alone DO NOT reduce energy consumption but can reduce electricity taken from the grid and the use of fossil fuels

• sustainability necessitates maximising our use of renewable resources in the energy supply to buildings

Sources 1 DUKES 2005, 2 NS Social trends 3 Energy consumption in the UK 4 NS Social trends, 5 domestic energy fact file 2001

Resources• In 1998 the construction industry consumed over 420

million tonnes of materials• 83% was primary materials• the construction industry accounted for around 80 million

tonnes of waste per year (4 x domestic waste)• the resource efficiency is 63%• the day-to-day operation of buildings also consumes

significant quantities of materials inc. treated water• sustainable buildings should use less raw materials

in their construction and produce less waste – through the use of re-cycled materials and re-cycling of waste, re-cycled aggregates, insulation materials, etc, use of ‘grey’ water, etc

Source: The Construction Industry Mass Balance: resource use, wastes and emissions R A Smith, J R Kersey and P J Griffiths

Community• the UK’s sustainable development priorities

also include the need for sustainable communities – covering the social aspect of buildings

• sustainable communities should be: – environmentally sensitive - providing places

for people to live that are considerate of the environment.

– well designed and built– well connected - with good transport services

and communication linking people to jobs, schools, health and other services

Legislation• also remember that new legislation is

emerging that forces designers to include sustainability:

• legislation, specifically related to sustainable buildings includes– Home Energy Conservation Act– London Energy Strategy (using planning

powers)– Local planning regulations– Energy Performance in Building’s Directive

(energy performance and renewables)– New building regulations (energy performance

and renewables)– Sustainable Building Codes (England)

Class Activity (revisited!)

• get back into your group of 4 and revise the 5 bullet points that encapsulate your understanding of a sustainable building

Achieving Sustainability• …. so sustainability in buildings encompasses a multitude

of factors but how can we achieve it?

resource use

energy use

emissions

renewables

occupants

local community

transport

waste and recycling

sustainabiltiy

Measuring Sustainability

• how can the resulting ‘sustainability’ of a design be assessed?

• single or multiple metrics?• UK government currently has 127

indicator measures and 68 indicators on sustainability

• not all relate to buildings

Performance Metrics

Performance Metrics• GHG emissions• energy consumption• renewable electricity/heat• resource use (water/fuel)• road transport• waste/recycling• air Pollutants• land use• …• community participation• employment/poverty• education

Performance Metrics• BREEAM is a very common voluntary sustainability

assessment method for buildings in the UK (LEED in the US)

• buildings are scored based on information entered into a spreadsheet

• outcome is a sustainability ‘score’ 0-100%• a systematic way to ensure that a broad range of

sustainability issues are considered at the design stage• however BREEAM does not allow us to predict the likely

sustainable performance of a building and it is not a measurement!

• to do this we need to develop models and then simulate performance

Performance Metrics

Modelling Sustainability

• to get a more robust measure of the likely sustainability of a building design we need to simulate the likely performance

• we use a mathematical model of our building with boundary data to simulate performance

• there are a range of simulation tools available to let us do this for buildings

• NB to judge performance we need to compare performance against a reference (base case or bench marks)

Modelling Sustainability

Building Design

Mathematical Model

Boundary data

Performance Data

Modelling Sustainability

Modelling Sustainability

• e.g. 1997 regs house vs passivhaus

• e.g. 1997 regs house vs passivhaus

Modelling Sustainability

UK Implementation

3

This Class

• in this class we will focus predominantly on sustainable energy issues

• providing a comfortable, healthy environment for the building occupant whilst minimizing our use of finite resources

• to achieve this our decisions will be informed by performance data and best practice

Postscript

• even simulation and modelling will not tell us exactly how a building will perform

• ALL modelling results are subject to error and uncertainty

• ultimately the only way to truly gauge performance is to measure it in the actual building

• …. however using a scientifically robust design process can improve the eventual sustainable performance of our buildings