Date post: | 14-Apr-2017 |
Category: |
Engineering |
Upload: | simon-owen-firp |
View: | 491 times |
Download: | 1 times |
1PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Yorkshire CIBSE
CIBSE Guide A 2015 and Overheating
Jon Nuttall and Richard Stokes
08.12.2015
2PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
1. Overheating Risk and Thermal Comfort
The problem with minimum compliance
Latest and greatest CIBSE assessment methods
Case Studies
2. Mitigation Strategies and the Cooling Hierarchy
3. Final Thoughts
Contents
3PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
About Hoare Lea
Offices throughout the UK and overseas
Founded in 1862 by Henry Lea
Remains a partnership wholly owned by the Partners
Fee turnover in excess of £50 million a year
Quality Assured to ISO9001
Over 420 design led technical staff, 500 in total
Award winning graduate recruitment and training scheme
4PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
We lead the way in energy strategy planning submissions
At least 50% more energy
strategy submissions than any
other consultant.
We also cover a wide range of
project sectors and sizes of
development
Source: South Bank University
Number of energy strategy submissions made to the GLA
responding to the London Plan: March 2009
Submissions to GLA
Energy Strategy Work
5PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Our approach to sustainability
6PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Overheating in Homes
Overheating Risk
Source: The Zero Carbon Hub
7PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Overheating Risk - Introduction
Thermal Comfort
Thermal comfort is complex and subjective.
Source: CIBSE TM52:2013
8PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Overheating Risk
Thermal Comfort
Overheating directly leads
to a low levels of thermal
comfort which can:
Lead to unhappy
occupants
Reduce the value of
new buildings
Expose design teams to
risk
Source: The Sunday Times
9PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Overheating Risk
Source: www.building.co.uk
Source: CIBSE Journal
10PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Overheating Risk
Introduction
Overheating occurs
when energy transfer
through building
envelope is
unbalanced
Heat Gains
Heat Losses
Source: Bing Images
11PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Overheating Risk
Heat GainsSource: Zero Carbon Hub: Overheating in Homes
12PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
A Modern Building Problem?
Although Part L has improved the efficiency of buildings in recent
years, a side effect is that increased insulation and reduced levels
of air leakage can limit beneficial heat loss in the summer.
Overheating Risk
13PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
A Modern Building Problem?
Additionally modern buildings are highly glazed…
Overheating Risk
14PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
A Modern Building Problem?
… and local conditions may inhibit the use of windows for
ventilation…
Overheating Risk
Source: Zero Carbon Hub: Overheating in Homes
15PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
A Modern Building Problem?
… whilst some dwellings can be particularly difficult to protect
from excessive solar gains, particularly single aspect West facing
homes.
Overheating Risk
Source: Zero Carbon Hub: Overheating in Homes
16PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Overheating Risk
17PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
A Contributing Factor
Climate change is contributing to warmer summers.
Overheating Risk
18PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
A Compounding Issue
The urban heat island
effect also effects new
dwellings in cities.
Overheating Risk
Urban Heat Island Effect in London
Up to +10°C Peak Daytime Temperatures
Source: Zero Carbon Hub Source: Arup, UK Space Agency, University College London
19PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Cumulative Effects
Overall, the risk of
overheating increases
with design, occupation
and surroundings.
Overheating Risk
Design
SurroundingsOccupation
20PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Assessing Overheating Risk
Overheating Risk
21PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Overheating Risk
Part L Criterion 3
The Building Regulations (Part L1A
criterion 3) only require simplified
calculations for new homes.
SAP Methodology determines the
‘likelihood’ that internal
temperatures exceed a threshold.
It is minimum compliance and also
mandatory for new dwellings.
22PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Overheating Risk
Part L Criterion 3Source: SAP v9.92
23PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Overheating Risk
UK – Average Temperature Data (1910 to 2015)
0
5
10
15
20
25
30
35
40
45
50
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
Fre
qu
en
cy o
f O
ccu
rre
nce
Temperature (°C)
Average Temperatures June July August
SAP uses the average
from this period
24PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Overheating Risk
UK – Peak Temperature Data (1910 to 2015)
0
5
10
15
20
25
30
35
40
45
50
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
Fre
qu
en
cy o
f O
ccu
rre
nce
Temperature (°C)
Average Temperatures June July August
0
5
10
15
20
25
30
35
40
45
50
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
Fre
qu
en
cy o
f O
ccu
rre
nce
Temperature (°C)
Peak TemperaturesJune July August
+6°C
In reality, peak
temperatures are much
higher on average…and
could be even higher…
25PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Overheating Risk
The Problem
It is based on:
SIMPLIFIED models
AVERAGE internal temperatures
AVERAGE monthly weather data
HISTORIC weather
RURAL weather
26PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Overheating Risk
The Problem
The Building Regulations (Part L2A
criterion 3) only considers solar heat
gains and is just for guidance.
27PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Overheating Risk
CIBSE Guide A 2006
Considers frequency of overheating
Uses 3D modelling
Dynamic hourly calculations
Results for each room
Proven in industry
28PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Overheating Risk
CIBSE Guide A 2015 / CIBSE TM52
For naturally ventilated buildings
Considers frequency, severity and a
maximum limit for overheating
Uses adaptive comfort, recognising
people accept warmer indoor
temperatures when its warmer outside
Customisable so can account for future
weather and urban heat island effect
29PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Overheating Risk
Adaptive What?
Research shows
people accept
warmer indoor
temperatures when
its warmer outside.
Therefore the
acceptability limits
(or comfort
threshold) should
also change.Source: CIBSE TM52: 2013
30PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Overheating Risk
CIBSE Guide A 2015 / CIBSE TM52
3 criteria to assess the risk of overheating.
A room or building that fails any two of the three criteria is
classed as overheating.
1) The number of hours that the operative temperature
can exceed the threshold by 1°C or more during the
occupied hours of a non-heating season (1 May to 30
September) shall not exceed 3%.
2) The severity of the overheating within one day must not
exceed a daily limit. This limit is defined in CIBSE TM 52
Section 6.1.2 (b).
3) The absolute maximum daily temperature of a
room is 4°C above the threshold.
31PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
A Note on Other Documents that Include Overheating…
32PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Case Study: Kirkstall Forge
Overheating Risk
33PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Overheating Risk
Example Analysis Part L1A Overheating vs. CIBSE Guide A
Kirkstall Forge, Leeds
Large Mixed Use Development
900 + New Homes
Hoare Lea providing Building Services, Acoustics and
Sustainability
Anticipated completion of first phase in 2017
http://www.kirkstallforge.com/
34PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Overheating Risk
Example SAP Analysis
Assessments carried
out using NHER Plan
Assessor v6.1.2
Assessing Part L 2013
Compliance
Criterion 3 Analysis:
1-2 Bed ~ 2.5 ACH
3-4 Bed ~ 2 ACH
?
35PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Overheating Risk
Example CIBSE Guide A 2006
Analysis
Assessments carried out
using IESve 2015
Bespoke thermal comfort
modelling
Analysis highlighted a
greater risk of overheating
36PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Overheating Risk
Example CIBSE Guide A 2015 Analysis
Assessments carried out using IESve 2015
Analysis indicated that a lower air change rate could be used
to minimise overheating risk
Source: CIBSE TM52: 2013
37PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Overheating Risk
CIBSE Guide A vs Part L – Analysis Summary
Entire Dwelling
Part
L1A
Cri
teri
on
3
Bedrooms Living Rooms
CIB
SE
Gu
ide A
2006
CIB
SE
Gu
ide
A
2015
Pass
All Pass
Pass
PassPass
Fail
Fail Fail
Fail
38PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Overheating Risk
Overheating Risk Mitigation
Cooling Hierarchy
1. Minimise Internal Heat Generation
2. Limit heat entering the building
3. Managing the heat within the building
4. Passive ventilation
5. Mechanical ventilation
6. Active cooling systems
39PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Overheating Risk
Minimise Internal Heat Generation
Recent beneficial trends:
Efficient internal equipment
Cloud based IT
40PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Overheating Risk
Limit Heat Entering the Building
• External shading / shutters
• Reduced glazing extent
• Tinted glass
41PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Overheating Risk
Limit Heat Entering the Building
• Interstitial shading within glazing
• Fritting
• Dynamic ‘smart’ glass
42PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Overheating Risk
Limit Heat Entering the Building
• ‘Light’ Internal Blinds
• ‘Light’ External shutters
43PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Overheating Risk
Thermal mass relies on
cool summer evenings
Less likely to occur
with urban heat island
effect
Managing Heat Within the Building
Source: Blue Ridge ICF
44PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Overheating Risk
Passive Ventilation
Openable windows
Stack ventilation
45PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Overheating Risk
Mechanical Ventilation
Can be limited by other measures
Spatial and cost implications
46PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Overheating Risk
Active Cooling
Excluded from Part L calculations, must comply without cooling
Can be designed out through passive design measures
47PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Summary
Overheating Risk
FeatureBuilding Regulations
Part L Criterion 3
Best Practice Dynamic Modelling
(CIBSE Guide A 2015)
Detail Fixed assumptions Fully flexible 3d model
Accuracy Monthly average temperatures Hourly inputs and outputs
RiskDoes not assess risk.Actual temperatures
can vary significantly from estimates
Modelling is predictive to assess the likely risk
of overheating
Weather Data Historical / average dataWorst case design summer year and future
weather can be used
ComfortOnly air temperature for dwellings and solar
gains for other buildings
Can report on adaptive thermal comfort and
percentage of people dissatisfied
Frequency Not identified Frequency of events can be identified
Severity Not identified Severity of events can be identified
Peak Only average data used Peak temperatures can be identified
Ratings None presently, may be input into HQMContributes to BREEAM and WELL Building
Ratings
48PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Final Thoughts
Overheating Risk
49PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Overheating Risk
Outdoor Thermal Comfort
50PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Urban Heat Island Effect
More Heat Rejection
Warmer Outdoor
Environment
Increased Cooling Demand
Increased Energy Use
Respiratory
difficulties
Heat cramps
Exhaustion
Heat stoke
Heat related
mortality
General
discomfort
Overheating Risk
51PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Overheating Risk
An Indicator for Outdoor Thermal Comfort
The temperate of dark materials can be several degrees hotter
than light materials
52PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Overheating Risk
Material and Landscaping Opportunities
53PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Overheating Risk
Solar Reflective Index (SRI)
54PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Overheating Risk
Opportunity
There is enough waste heat in London to
meet the existing heating demand. This heat
is from:
Buildings
Geothermal
Infrastructure
Transformers
55PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Overheating Risk
Opportunity
XXX
Source: London Borough of Islington
Source: Ooms Civiel (Netherlands)Source: GLA Secondary Heat Report
56PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Overheating Risk
Example: New York Cool Roofs
80°C
0°C
40°C
60°C
20°CWhite Painted Roofs
Black Painted Roofs
Surf
ace T
em
pera
ture
s
Source: www.coolroofs.org
57PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Overheating Risk
Example: 20 Fenchurch (Walkie Scorchie)
58PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A
Thank you.
Any questions?
59PRES_RS_JN-20151207-CIBSE Guide A 2015 and Overheating-CIBSE Yorkshire-Rev A