Transcript Adaptability and Change: Low energy design, urban microclimate and climate change

Adaptability and Change:
Low energy design, urban microclimate and climate change
Introduction
Air conditioning
Adaptive comfort
Adaptive design
Comfort criteria
Koen Steemers
Cambridge Architectural Research Limited
and
The Martin Centre for Architectural and Urban Studies
Department of Architecture, University of Cambridge
Conclusions
Adaptability and Change:
Low energy design, urban microclimate and climate change
The dilemma
Buildings cause 40-50% of emissions,
creating pollution & climate change.
Buildings will be affected by the urban
microclimate and climate change.
1. Reduce the energy consumption and
emissions of buildings e.g. through
passive design.
2. The urban climate and climate change
can make the energy performance of
buildings worse, or environmentally
unacceptable to the occupants.
Introduction
Air conditioning
Adaptive comfort
Adaptive design
Comfort criteria
Conclusions
Adaptability and Change:
Low energy design, urban microclimate and climate change
Overview:
• The urban environment and climate
change has begun to enter the
consciousness of the construction
industry.
• The worry is that the response will be
negative – i.e. to increase the defensive
capabilities of the building by throwing
more energy use and systems at it.
The result would be increased energy
use, increased emissions and thus
increased rate of climate change…not
a sustainable sequence of events.
Introduction
Air conditioning
Adaptive comfort
Adaptive design
Comfort criteria
Conclusions
Adaptability and Change:
Low energy design, urban microclimate and climate change
The challenge:
1. To show that increased energy use (e.g.
conventional air conditioning) is not the
solution to adapting to the urban
microclimate or climate change.
2. To demonstrate how low energy design
and comfort theory can address both
mitigation and adaptation.
Introduction
Air conditioning
Adaptive comfort
Adaptive design
Comfort criteria
Conclusions
Adaptability and Change:
Low energy design, urban microclimate and climate change
• Our senses have evolved to respond to a
dynamic environment.
• Yet our buildings have become
increasingly closely controlled, whilst
consuming significantly greater amounts
of energy.
heating
22%
Nat Vent
fans/pumps
12%
Air Con
lighting
34%
Air conditioning
Adaptive comfort
Adaptive design
Comfort criteria
fans/pumps
30%
Conclusions
heating
41%
lighting
47%
Introduction
refrigeration
14%
Adaptability and Change:
Low energy design, urban microclimate and climate change
Implications of poor air con:
•
•
•
•
Reduced indoor air quality
Sick building syndrome
Increased absenteeism
Reduced productivity
Introduction
Air conditioning
Adaptive comfort
Adaptive design
Comfort criteria
Performance can be radically different
from that predicted – energy figures
of twice those calculated are not rare
in the first year of operation.
Why?
Conclusions
Adaptability and Change:
Low energy design, urban microclimate and climate change
Performance discrepancies:
Introduction
• hasty commissioning
• lack of awareness of occupant
interaction
• lack of post occupancy surveys
• rare feedback to the design team
Air conditioning
Adaptive comfort
Adaptive design
Comfort criteria
Conclusions
As a result, the construction industry
tends to be slow to learn, change and
adapt to new challenges.
Adaptability and Change:
Low energy design, urban microclimate and climate change
• Mechanical control is in its infancy
• Passive design has centuries of tried and
tested strategies
Introduction
Air conditioning
Adaptive comfort
Improved understanding of the
interactions between building,
environmental performance and
occupant satisfaction is emerging.
- form and fabric are an integral part of the
environmental strategy
- reducing the reliance on mechanical systems
- enabling the occupant to adapt and interact with
their own environment
Adaptive design
Comfort criteria
Conclusions
Adaptability and Change:
Low energy design, urban microclimate and climate change
Low energy design and comfort
• Examples from extreme climates
• Adaptation of design and the occupants
• Relevant to challenges presented by the
urban microclimate and climate change
Introduction
Air conditioning
Adaptive comfort
Adaptive design
Comfort criteria
Conclusions
Adaptability and Change:
Low energy design, urban microclimate and climate change
Hot-arid: Courtyard buildings
• Spaces (and locations within spaces)
offering improved comfort conditions are
consistently sought by occupants.
Introduction
Air conditioning
Adaptive comfort
Adaptive design
Comfort criteria
Conclusions
Source: Abu Merghani, The Martin Centre, University of Cambridge
Adaptability and Change:
Low energy design, urban microclimate and climate change
A range of spatial conditions: internal
rooms, intermediate verandas and
external courtyards, with various thermal
characteristics.
100
Oudoor spaces
Intermediate spaces
Percengtage of time
80
Introduction
Air conditioning
Adaptive comfort
Adaptive design
Comfort criteria
Indoor spaces
60
Conclusions
40
20
0
B1-1 Jan
B1-2 Mar
B1-3 Apr
B1-4 May
B1-5 June
Source: Abu Merghani, The Martin Centre, University of Cambridge
Adaptability and Change:
Low energy design, urban microclimate and climate change
• Other adaptive opportunities: deploying
openings and shading, changes to dress,
activity level, posture, hot/cold drinks,
sprinkling of courtyard and use of fans.
• The range and accumulation of adaptive
opportunities available significantly
improves comfort.
Source: Nick Baker, The
Martin Centre, University
of Cambridge
air temp
rad temp
air speed
clo
met
PPD
base case
30.5
30.5
0.1
0.5
1.2
68.4%
adapted case
28.0
28.0
0.2
0.4
1.1
17.5%
Introduction
Air conditioning
Adaptive comfort
Adaptive design
Comfort criteria
Conclusions
Adaptability and Change:
Low energy design, urban microclimate and climate change
The adaptive office:
• Trend towards more flexible working
patterns and office layouts, exemplified
by the work of Frank Duffy and DEGW.
• Though not explicitly linked to comfort
seeking, the notion of for example ‘hotdesking’ offers that potential.
• Also, efficient space use means less
floor space, which in turn could reduce
the energy use per occupant.
Introduction
Air conditioning
Adaptive comfort
Adaptive design
Comfort criteria
Conclusions
Adaptability and Change:
Low energy design, urban microclimate and climate change
Adaptive building envelope:
• Perceived comfort and productivity are
associated with the opportunity to
interact with the building envelope.
– e.g. views, operable windows and blinds.
• Small windows v. glazed facades:
–
–
–
–
–
–
temporary spatial adjustments to avoid sun;
more thermal mass;
reduced solar gains;
less need for shading (nb daylight and views);
localised ventilation;
reduced costs, etc.
Introduction
Air conditioning
Adaptive comfort
Adaptive design
Comfort criteria
Conclusions
Adaptability and Change:
Low energy design, urban microclimate and climate change
Adaptive systems:
• Avoid centralised BMS which leaves the
occupants powerless.
• Use sensors and controls which enable
local occupant interaction.
• Use systems that respond to occupant
interaction with the building (e.g. opening
a window turns off heat).
• The system should serve the occupant,
combining robust climatic design with
intelligent controls and components, to
maximise adaptability.
Introduction
Air conditioning
Adaptive comfort
Adaptive design
Comfort criteria
Conclusions
Adaptability and Change:
Low energy design, urban microclimate and climate change
Comfort criteria:
• Generally: 27oC <2% of occupied period.
• CIBSE: 25oC <5% of occupied period.
• A change from 27 to 25oC is a step back,
particularly in the light of climate change.
Days of overheating
60
Introduction
Air conditioning
Adaptive comfort
Adaptive design
Comfort criteria
50
Conclusions
40
30
20
10
0
Light (27) Med (27) Heavy (27) Light (25) Med (25) Heavy (25)
Adaptability and Change:
Low energy design, urban microclimate and climate change
Applying the criteria:
• Either criterion requires quite
sophisticated dynamic thermal modeling.
• Despite such sophistication, no account
is taken of adaptive opportunities – a key
determinant of comfort and energy use.
• Detailed simulation is only as good as
the input data and assumptions, and
reveals little about the robustness of a
design.
Introduction
Air conditioning
Adaptive comfort
Adaptive design
Comfort criteria
Conclusions
Adaptability and Change:
Low energy design, urban microclimate and climate change
Introduction
Air conditioning
Adaptive comfort
Adaptive design
Comfort criteria
Conclusions
Adaptability and Change:
Low energy design, urban microclimate and climate change
Conclusions:
• Adaptation, through building design and
occupant interaction (spatial, personal
and systems control).
• Current criteria are insufficient to
determine occupant comfort, complex to
apply, and likely to result in the increased
energy demand.
• EU standards should be designed so as
not to limit diversity and regionalism.
Introduction
Air conditioning
Adaptive comfort
Adaptive design
Comfort criteria
Conclusions
Adaptability and Change:
Low energy design, urban microclimate and climate change
Introduction
Conclusions:
Air conditioning
Adaptive comfort
Adaptive design
Comfort criteria
Conclusions
School, Como, Italy (Terragni)
Library, Viipuri, Finland (Aalto)
Source: Peter Fisher, The Martin Centre, University of Cambridge
Adaptability and Change:
Low energy design, urban microclimate and climate change
Introduction
The
End
Air conditioning
Adaptive comfort
Adaptive design
Comfort criteria
Conclusions
Adaptability and Change:
Low energy design, urban microclimate and climate change