BC Energy Step Code Design Guide Supplement S3 on Overheating and Air Quality - June 2019 - BC Housing
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BC Energy Step Code
Design Guide Supplement S3 on
Overheating and Air Quality
June 2019
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SUPPLEMENT S3
Version 1.0
About This Supplement Disclaimer Acknowledgements
The greatest care has been taken to confirm the accuracy of the This guide was funded and commissioned by BC Housing, BC Hydro, the City of Vancouver, the
The Design Guide Supplement on Overheating and Air
information contained herein. However, the authors, funders, City of New Westminster, and the Province of BC. Acknowledgement is extended to all those who
Quality was published by BC Housing in collaboration publisher, and other contributors assume no liability for any participated in this project as part of the project team or as external reviewers.
with BC Hydro, the City of Vancouver, the City of New damage, injury, loss, or expense that may be incurred or suffered
as a result of the use of this publication, including products,
Westminster, and the Province of BC. It provides building techniques, or practices. The views expressed herein Produced by:
information on the key strategies and approaches do not necessarily represent those of any individual contributor, HCMA Architecture + Design Integral Group
necessary to reduce the impacts of a warmer climate BC Housing, BC Hydro, the City of New Westminster, the City Johnathon Strebly, Bonnie Retief, Judy Bau Lisa Westerhoff, Chris Doel, Craig Dedels
of Vancouver, or the Province of British Columbia. As products
on mid- and high-rise (Part 3) wood-frame and non- and construction practices change and improve over time, it is
Focal Engineering
combustible residential buildings within British Columbia. advisable to regularly consult up-to-date technical publications
Susan MacDougall, Riley Beise, Sarah Shepherd
on building science, products, and practices, rather than relying
Specifically, it is intended to provide building industry
solely on this publication. It is also advisable to seek specific
actors, including local governments, public sector information on the use of products, the requirements of good External Reviewers:
organizations, architects, and developers, with an design and construction practices, and the requirements of the
applicable building codes before undertaking a construction AIBC Fraser Health
accessible source of information on the key means of project. Retain consultants with appropriate engineering Maura Gatensby Ghazal Ebrahimi, Angie Woo
addressing issues of overheating and indoor air quality. or architectural qualifications, as well as the appropriate
municipal and other authorities, regarding issues of design and
BC Housing ICLEI Canada
construction practices, and compliance with the British Columbia
This supplement can be used as a stand-alone resource, Building Code (BCBC) and Vancouver’s Building By-law (VBBL). Wilma Leung, Bill Mackinnon, Craig Brown
Magda Szpala, Remi Charron
but is intended to complement the BC Energy Step Code The use of this guide does not guarantee compliance with code
requirements, nor does the use of systems not covered by this Province of British Columbia
Design Guide and should be consulted alongside the guide preclude compliance. BC Hydro Zachary May, Emily Sinclair
strategies presented to meet the targets under the BC Gary Hamer, Toby Lau
Energy Step Code. Strategies outlined in the guide comply University of British Columbia
with the BC Energy Step Code across the province, but are City of New Westminster Ralph Wells
also compatible with those projects seeking compliance Norm Connolly
with the City of Vancouver’s Zero Emissions Building Plan. University of Toronto
City of Vancouver Ted Kesik
Patrick Enright
This supplement is also one in a series of design guides
Vancouver Coastal Health
designed to support an industry transition toward a Engineers and Geoscientists BC Emily Peterson
future in which safe, resilient and adaptive buildings are Harshan Radhakrishnan
business-as-usual. For more information and access
to other resources, guidelines, primers on climate
change resilience, and details on the Mobilizing Building
Adaptation and Resilience (MBAR) project, visit the BC
Housing website at www.bchousing.org/research-centre.
BC ENERGY STEP CODE DESIGN GUIDE SUPPLEMENT S3 OVERHEATING AND AIR QUALITY
Table of Contents
S3-01 SECTION S3-01 S3-04 SECTION S3-04
Introduction Key Design Strategies
01.1 Introduction Page 05 04.0 Key Design Strategies Page 18
The Purpose of the Design Guide Supplement Page 06 04.1 Passively Cool the Building Page 19
Who Is This For? Page 06 04.2 Use Shading to Block Solar Heat Gains Page 22
04.3 Cooling via Natural Ventilation Page 25
S3-02 SECTION S3-02 04.4 Couple Passive Cooling with Active Approaches Page 28
Risk and Resilience in Building Design 04.5 Add a Source of Cooling Page 30
04.6 Filter the Air Page 34
02.0 Resilience in Building Design Page 08
04.7 Include a Refuge Area into Building Design Page 35
Designing for Comfort and Safety Page 08
02.1 What is Overheating? Page 09
02.2 What is Indoor Air Quality? Page 11 A APPENDIX
02.3 A Balancing Act Page 12 Resources
A1 Glossary of Terms Page 38
S3-03 SECTION S3-03 A2 Image Sources Page 40
Modelling for a Future Climate
03.0 Modelling for a Future Climate Page 14
03.1 Understanding Weather Data Page 14
03.2 Performing a Future Climate Analysis Page 15
TABLE OF CONTENTS 03
BC ENERGY STEP CODE DESIGN GUIDE SUPPLEMENT S3 OVERHEATING AND AIR QUALITY SECTION S3-01.
.
SECTION S3-01.
Introduction
01.1 Introduction
The Purpose of the Design Guide Supplement
Who Is This For?
0 1
04
BC ENERGY STEP CODE DESIGN GUIDE SUPPLEMENT S3 OVERHEATING AND AIR QUALITY INTRODUCTION SECTION S3-01.
S3-01 Introduction
Buildings play a key role in preventing the adverse effects
of climate change by employing design strategies to both
reduce greenhouse gas (GHG) emissions and adapt to
current and projected impacts.
To help reduce emissions from buildings, the Province of British Columbia
has taken a number of actions. Under the umbrella of the CleanBC
program, one such action is the release of the BC Energy Step Code, which
sets energy performance requirements for new buildings as a means of Additional References
reducing their energy use and emissions.
At the same time, the Province is projected to experience significant Preparing for Climate Change: Climate Projections for the Cowichan Valley Regional District
changes in climate over the next several decades, which will have British Columbia’s Adaptation Strategy Cowichan Valley Regional District
considerable impacts on building performance. Preparing for Change: Province of British Columbia 2017
2010
British Columbia’s Adaptation Strategy, projects overall temperature
increases of between 1.3 and 2.7°C by the year 2050, as well as heavier Moving Towards Climate Resilient Health Facilities
rains, longer dry spells, more heat waves and more severe wildfire events.¹ Special Report: Global Warming of 1.5°C for Vancouver Coastal Health
Such impacts can pose serious risks to British Columbia’s buildings and Intergovernmental Panel on Climate Change Lower Mainland Facilities Management
2018 2018
the safety, well-being, and financial investments of their owners and
occupants. Indeed, the average temperature across the province has
already increased by 1.4°C over the last hundred years, with impacts on Resilience Planning New Construction BC Building Code – Appendix C
the built environment already occurring in different regions.1 City of Toronto Province of British Columbia
2017 2018
Buildings can be designed to increase their resilience to these changes
and in doing so, increase both their quality and overall value. Buildings Climate Projections for Metro Vancouver Update on Extreme Heat and Maximum Indoor Temperature
Metro Vancouver Standard for Multi-unit Residential Buildings
constructed today should be designed in such a way that the comfort and
2016 Toronto Public Health
safety of their occupants is ensured for the lifetime of the building. This is
2015
especially important as current building codes and standards are reflective
Climate Projections for the Capital Regional District
of historical experiences – that is, they are based on past climatic
Capital Regional District Filtration in Institutional Settings During Wildfire Smoke Events
conditions, and don’t necessarily consider the impacts of a warmer world
2017 BC Centre for Disease Control
on the health, comfort, and safety of building occupants. Looking to future
2014
conditions is an increasingly important part of building design across all
regions of the province.
¹ https://www2.gov.bc.ca/gov/content/environment/climate-change/adaptation/impacts
05
BC ENERGY STEP CODE DESIGN GUIDE SUPPLEMENT S3 OVERHEATING AND AIR QUALITY INTRODUCTION SECTION S3-01.
The Purpose of the Design Guide Supplement Who Is This For?
While potential climate change impacts on the built environment range by region and This guide is a resource for local governments and design teams interested in pursuing the
precise project location, this resource presents a set of design principles, strategies and BC Energy Step Code.
practices intended to reduce the risk of two significant climate-related issues:
1
Overheating
due to higher average
H M
IG U
temperature and increases in
H RB
-R
IS
extreme temperature events
E
(such as heat waves)
M M
ID UR
-R B
IS
E
2
Indoor air quality issues
due to an increase in wildfire
events (as well as more
localized sources of air
pollutants)
The information is intended primarily for Part 3 High-Rise For those pursuing the BC Energy Step Code, the LOCAL GOVERNMENTS DESIGN TEAMS
and Mid-Rise Multi-Unit Residential Buildings (MURB) supplement is intended to complement the rest
Planners, urban designers, and other members of Developers, architects, mechanical and building envelope
in British Columbia, and is most relevant for buildings of the BC Energy Step Code Design Guide and
local government staff can play a role in supporting engineers, and energy modellers all have a role to play in the
constructed in Climate Zones 4 and 5. However, several should be referenced alongside it. However, the
resilient buildings by encouraging the submission of design of safe, comfortable, and resilient buildings. Design teams
of the strategies will also be useful and applicable to guide will serve as a useful resource for those
applications that indicate how climate change adaptation that explore strategies to improve building resilience early on
projects located in higher climate zones and to Part 9 working outside of British Columbia as well.
strategies have been incorporated into building design. in the design process can more successfully identify ways to
MURB. While the information contained in this guide is Local governments can use this guide as a means of harness efficiencies and reduce overall costs. Teams should use
relevant mainly to new buildings, many strategies can understanding and promoting resilient building strategies. this resource in conjunction with the rest of the BC Energy Step
also be applied to renovations of existing buildings. Code Design Guide to explore different design strategies for their
potential to simultaneously improve energy efficiency, reduce
GHG emissions, and improve overall building resilience.
WHY AND WHO? 06
BC ENERGY STEP CODE DESIGN GUIDE SUPPLEMENT S3 OVERHEATING AND AIR QUALITY SECTION S3-02.
SECTION S3-02.
.
Risk and Resilience
in Building Design
02
02.0 Resilience in Building Design
Designing for Comfort and Safety
02.1 What is Overheating?
02.2 What is Indoor Air Quality?
02.3 A Balancing Act
07
BC ENERGY STEP CODE DESIGN GUIDE SUPPLEMENT S3 OVERHEATING AND AIR QUALITY RISK AND RESILIENCE IN BUILDING DESIGN SECTION S3-02.
Resilience in Building Design Key Terms Designing for Comfort and Safety
PASSIVE SURVIVABILITY is the
The idea of resilience refers to the ability of a extent of a building’s ability to
Designing for the most vulnerable occupants of a building can be a way to ensure that all occupants
system (such as a building) to anticipate, absorb, maintain healthy, liveable conditions remain comfortable and healthy. This approach should be used by carefully considering the building’s
in the event of extended loss of
accommodate, or recover from the effects of an power or water, or in the event of
expected occupancy, and identifying strategies that benefit all occupants.
event or stress in a timely and efficient manner. extraordinary heat waves, storms
or other extreme events. Resilient building design involves the need to maintain overall For example, a highly resilient building can act as a refuge centre
The way in which a building adapts to an event
health and well-being of all building occupants. Designed, for a block or neighbourhood during extreme events by providing
(e.g. air quality advisory) or ongoing stress SHOCK is an acute natural or
constructed, and managed thoughtfully, a resilient building can access to communal spaces with power, cooling, and good
human-made event or phenomenon
(e.g. elevated summer temperatures) depends threatening major loss of life,
actually improve its core functions over the business-as-usual, ventilation. Such centres can provide important resources during
and offer a safer, more comfortable alternative for both its a range of extreme events, from heat waves to extreme storms
on a number of factors, including its location, damage to assets and a building or
occupants and the broader community. and earthquakes.
community's ability to function and
design, operations, and maintenance. provide basic services (e.g. heat
wave, wildfire).
In general, a resilient building is one that is able to: STRESS is a chronic (i.e. ongoing
or cyclical) natural or human-made 1 Occupants with respiratory issues
1 event or phenomenon that renders
a building or community less able to 2 Pregnant occupants and unborn children
Maintain critical operations and functions in the face of either
function and provide basic services
an acute shock or chronic stress, and return to normal operations 3 Elderly occupants
(e.g. increased temperatures).
in a fast and efficient manner, in order to maintain healthy, 2 3
liveable spaces for its occupants.
4 Infants and young children
THERMAL RESILIENCE is the
ability of a building to achieve
2 thermal comfort in the event of
Improve the overall health and well-being of its occupants power outages by improving
through its design and operation. weatherization and insulation,
increasing air circulation, reducing
solar gains through windows,
increasing natural ventilation, and
minimizing internal heat gains.
1
VULNERABLE POPULATIONS
are groups and communities
at a higher risk for poor health
as a result of the barriers they
experience to social, economic,
political and environmental
4
resources, as well as limitations
due to illness or disability. These
include children, pregnant women,
elderly people, people with low
incomes, and people who are
ill or immunocompromised.
A RESOURCE FOR LOCAL GOVERNMENTS 08
BC ENERGY STEP CODE DESIGN GUIDE SUPPLEMENT S3 OVERHEATING AND AIR QUALITY RISK AND RESILIENCE IN BUILDING DESIGN SECTION S3-02.
02.1 What is Overheating?
Overheating occurs when a space becomes too warm for its occupants.
Prolonged or dangerously high temperatures can cause health risks, such as TIA
L
T EN RISK
heat stress, heatstroke, increased morbidity or even mortality, particularly in PO LTH
A
LO
SS HE
AT
vulnerable populations. Indeed, exposure to indoor temperatures above 26°C W
HE
ES
LO
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R-VIGH
T
A
has been associated with increased premature mortality and emergency
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medical services calls 2, 3.
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80
IN
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20
R
Overheating vs. Designing for CO
C
IN
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SS DIS
AT
Thermal Comfort Thermal Comfort LO
W
HE
Related to the concept of overheating is While experiences of thermal comfort can vary,
thermal comfort, which is achieved when an ASHRAE Standard 55 – Thermal Environmental
occupant is satisfied with the temperature in Conditions for Human Occupancy is a LLY
50
MA LE
ER RTAB
20
a particular space. Individuals’ experience of research-based standard that outlines specific H
T FO
SS M
thermal comfort is complex, highly subjective methodologies to predict and measure occupant LO CO
AT
HE
W
and can depend on: thermal comfort for healthy adults. LO
1 Individual characteristics ASHRAE Standard 55 generally recommends
(e.g. age, metabolic rate, size, occupied spaces to be designed to stay
overall health, preference)
16
below 24-25°C (dry bulb) in the winter and
20
2 Behavioural factors 27-28°C (dry bulb) in the summer to prevent
(e.g. whether a person is at rest, overheating. However, this can vary based on
sitting, walking, or exercising) the intended use of the space, as well as other
S
R
EA
factors. For example, young children may not
Y
3 Cultural norms
(e.g. type of attire worn) be able to cope with higher temperatures.
4 Physical considerations
(e.g. air and radiant temperatures,
air speed and relative humidity)
Comfort Today Can Be Discomfort Tomorrow
In 2009, British Columbia experienced a heat As temperatures continue to increase, so too performance building envelopes can retain
While it may not pose health risks for everyone, wave that contributed to an additional 110 will the likelihood and magnitude of overheating more heat in the summer.
overheating-related deaths per week 4. in our buildings. Spaces that are designed to be
the experience of thermal discomfort comfortable today are likely to become Overall, designers will need to provide an
can impact quality of life. Globally, the five hottest years have all occurred uncomfortable under future climate conditions adequate source of cooling using both passive
since that year 5, and even warmer temperatures if care isn’t taken to consider increasing and active building strategies to maintain the
For instance, occupants may not be able to use building spaces as they were designed to (e.g. a bedroom are anticipated in the future. temperatures. Energy efficient buildings can be comfort and livability of our buildings.
may be too warm to sleep in). Occupants may leave a building altogether if it becomes uncomfortably especially at risk of overheating, as higher
hot, interrupting their ability to live and work normally.
2
https://www.toronto.ca/legdocs/mmis/2015/hl/bgrd/backgroundfile-85835.pdf
3
https://www.tandfonline.com/doi/pdf/10.1080/23328940.2018.1456257 WHAT IS OVERHEATING? 09
4
https://www.cbc.ca/news/canada/british-columbia/heat-warning-change-environment-canada-1.4762636
5
http://www.climatecentral.org/gallery/graphics/the-10-hottest-global-years-on-record
BC ENERGY STEP CODE DESIGN GUIDE SUPPLEMENT S3 OVERHEATING AND AIR QUALITY RISK AND RESILIENCE IN BUILDING DESIGN SECTION S3-02.
Factors Involved in Overheating Limiting Overheating
Overheating can be caused by a combination of physical, behavioural and climatic factors. Both the BC Energy Step Code (BCESC) and the
City of Vancouver Zero Emissions Building Plan
(ZEBP) set limits for overheating.
6
For spaces that do not use any mechanical cooling,
temperatures cannot exceed “80% acceptability limits” for
more than 200 hours during the summer months. The 80%
acceptability limit is a specific temperature during the summer
5 months at which overheating can be a concern, which varies
depending on the building’s location. This limit is calculated
3 using a methodology defined in ASHRAE Standard 55. A full
definition can be found in the City of Vancouver Energy Modelling
4
Guidelines v2.0. It is important to note that buildings that house
vulnerable populations have a lower limit of 20 hours, but owners
32ºC and project teams may target a lower number to limit the risk of
2
70% overheating for project type.
% humidity
For spaces that make use of mechanical cooling, design teams
must demonstrate that each space will experience less than
100 “unmet cooling hours” per year. Unmet cooling hours occur
7 when a cooling system is unable to achieve the desired indoor
temperature. A full definition of unmet cooling hours can be
found in NECB 2015 – Section 8.4.1.2 Determination
7 of Compliance.
4
International Guidance
1 The Chartered Institution of Building Services Engineers
(CIBSE, similar to ASHRAE in the United Kingdom) provides tools
to reduce the risk of overheating through Technical Memoranda
TM52 and TM59. These set a 3% limit on the number of hours
that a space’s indoor temperature can exceed the threshold
comfort temperature by 1°C or more during the occupied hours
1 2 3 4 5 6 7 of a typical non-heating season. Overheating limits are also set
Contextual or situational High external Internal heat gains Internal heat gains from High wall and roof Absorption of heat by Lack of adequate for the severity of overheating on a given day (i.e. the number
factors that prevent temperatures and/or via incoming solar lighting, equipment, insulation and/or the buildings structure ventilation that could of hours), as well as an absolute maximum daily temperature
occupants from opening extreme humidity levels radiation through the occupants and occupant building airtightness that that create high surface assist in cooling for each room. For example, bedrooms cannot exceed an
their windows (e.g. building glazing activities retain internal heat gains temperatures operative temperature of 26°C for >1% annual night-time
noise, pollution, poor hours, between the hours of 22:00 and 07:00.
outdoor air quality)
LIMITING OVERHEATING 10BC ENERGY STEP CODE DESIGN GUIDE SUPPLEMENT S3 OVERHEATING AND AIR QUALITY RISK AND RESILIENCE IN BUILDING DESIGN SECTION S3-02.
02.2 What is Indoor Air Quality? Factors Involved in Poor Indoor Air Quality
Indoor air quality is an important determinant of the health of building 1 2 3
Indoor sources of contaminants include cleaning Outdoor sources of contaminants that vary Outdoor sources of contaminants that affect entire
occupants and is affected by both indoor and outdoor factors.
products, off-gassing from building materials and depending on local context, and include traffic, regions, including urban smog due to increased
furnishings, cooking, and parkade exhaust, among industry, construction, and hazmat emergencies ground-level ozone, and wildfire smoke events
others. High noise levels outside may also force involving flammable or poisonous substances. that will increase in frequency and severity with
BC Air Quality Projections Air Quality Standards occupants to close their windows, increasing the climate change.
risk of poor indoor air quality.
Climate change projections for BC include The BC Building Code (BCBC) recognizes that
an increase in the number of wildfire smoke outdoor air may not always be of an acceptable TRAFFIC
events. This smoke contains a mixture of quality for ventilating buildings unless certain WILDFIRE
fine particulate matter, carbon monoxide, particles and gases are first removed or COOKING
nitrogen oxides, volatile organic compounds, reduced. Code requirements for indoor air
INDUSTRY
and heavy metals. Studies also predict quality are outlined in the BCBC and
increased levels of ozone in the summer ASHRAE 62.1, and set minimum ventilation
CLEANING PRODUCTS
months. While ozone in the stratosphere requirements to maintain CO2 concentrations
plays a beneficial role in offering protection below a certain threshold. CONSTRUCTION
from the sun’s ultraviolet rays, ozone near
the ground contributes to the formation or Developers interested in pursuing higher air MATERIAL OFF-GASSING
urban smog and is harmful to breathe. quality standards can find examples in the HAZMAT EMERGENCIES
Leadership in Energy and Environmental
Exposure to air contaminants have been Design (LEED) standard and the WELL Building
linked to several short- and long-term Standard™, both of which define thresholds for
NOISE
health effects, including: various pollutants. These standards require
• Fatigue verification to demonstrate compliance
• Headaches with their set thresholds, and assess the
• Eye/nose/throat irritation effectiveness of ventilation systems to verify
• Impaired cognitive function/decline that a sufficient level of ventilation is provided.
• Respiratory diseases
• Cardiovascular disease
• Diabetes and obesity
• Cancer
WHAT IS INDOOR AIR QUALITY? 11BC ENERGY STEP CODE DESIGN GUIDE SUPPLEMENT S3 OVERHEATING AND AIR QUALITY RISK AND RESILIENCE IN BUILDING DESIGN SECTION S3-02.
02.3 A Balancing Act
Design strategies that minimize overheating and indoor air quality issues can 1 2 3 4
impact a building’s chances of achieving the targets of either the BC Energy Exterior shading can be an Operable windows allow Low solar heat gain glazing Mechanical cooling can eliminate any overheating
Step Code and/or the City of Vancouver’s Zero Emissions Building Plan. It is effective strategy for reducing risk occupants to passively cool can reduce the risk of issues, but at the expense of increased energy use,
of overheating. However, it can their space. In some situations, overheating. As with shading, increasing TEUI. This can also help with indoor
therefore important to understand the relationship between these targets. also block desired passive solar this unfiltered air may have however, this may also block environmental quality since it can allow the occupant
heating in winter if not carefully an adverse effect on indoor desired passive solar heating in to keep windows closed, keeping both noise and
designed, increasing TEDI. air quality. winter, increasing TEDI. contaminated outdoor air out.
Total Energy Use Airtightness
Intensity (TEUI) (AT)
Lower risk of Lower risk of Lower risk of Lower risk of Lower risk of
Passive cooling strategies, such as operable Improved airtightness leads to better OVERHEATING OVERHEATING OVERHEATING OVERHEATING POOR IAQ
windows, help to reduce a building’s TEUI. TEDI performance and reduces the risk of
However, they can be unsuitable under indoor air quality issues from outdoor sources.
conditions of poor exterior air quality, as they A more airtight building envelope is highly Higher Higher risk of Higher Higher
TEDI POOR IAQ TEDI TEUI
let in unfiltered air. Using mechanical cooling to effective in reducing winter heat loss. However,
keep a space comfortable in the summer can a less airtight building will not help to dissipate
help to prevent poor outdoor air quality from summer heat, making airtightness an important
entering the building, especially when some consideration for all building designs. THE RIGHT TOOLS FOR THE JOB
degree of filtration is added.
Proper evaluation of strategies such as exterior
HEAT shading and operable windows can be complex
PUMP
Thermal Energy City of Vancouver ZEBP and require the use of powerful simulation tools.
Demand Intensity Greenhouse Gas Intensity Ensure your team has the right tools to provide
(TEDI) (GHGI) good quality information for making decisions.
A high-performance building envelope will lead Depending on the system that is used, 1
4
to better TEDI performance and can slow the mechanical cooling can increase both the TEUI
movement of summer heat into the building. and the GHGI of a building. Using heat pumps 2
However, it can also lead to overheating issues for both heating and cooling can reduce a KEY TAKEAWAY
when internal gains are trapped inside during building’s GHG emissions when compared to 3
the summer months. Passive cooling strategies Consider the impacts of design strategies
a natural gas-based or lower-efficiency electric
designed to reduce overheating can also result used to achieve energy efficiency or emissions
heating system.
in an increase in a building’s overall TEDI in the reductions on occupants’ thermal comfort and
winter by reducing passive solar gains. indoor air quality.
A BALANCING ACT 12BC ENERGY STEP CODE DESIGN GUIDE SUPPLEMENT S3 OVERHEATING AND AIR QUALITY SECTION S3-03.
SECTION S3-03.
.
Modelling for
3
a Future Climate
0
03.0 Modelling for a Future Climate
03.1 Understanding Weather Data
03.2 Performing a Future Climate Analysis
13BC ENERGY STEP CODE DESIGN GUIDE SUPPLEMENT S3 OVERHEATING AND AIR QUALITY MODELLING FOR A FUTURE CLIMATE SECTION S3-03.
03.0 Modelling for a Future Climate
One of the key ways that design teams can explore a building’s potential
for overheating is by using an energy model.
A Common Example of Weather File Used in Energy Simulation
Energy models are used to assess the impact Adopting an approach to energy modelling that
of a building’s design on occupants’ comfort by takes future climate conditions into account can
simulating building performance using different help design teams and owners make decisions
assumptions, including assumptions around today that will last the life of the building. This is
the weather. However, standard approaches to particularly important given that occupants will 600
energy modelling use weather files that are based be using these buildings for the next 50 years,
on 30 years of historical data – in other words, if not more.
the climate of the past. Since the climate has 500
continued to warm and change, these weather
Annual Hours at Temperature*
files are unable to accurately represent current
conditions, let alone future conditions.
400
03.1 Understanding Weather Data 300
To model for a future climate, Design Data represent peak conditions for a
location and are used for sizing mechanical 200
energy modellers need future heating and cooling equipment. These data
BCBC 1% BCBC 2.5%
climatic data. These data come in are provided in the National Building Code, BC Heating Design Cooling Design
different formats, and often have Building Code and Vancouver Building Bylaw.
100
different intended uses. Design data use near-worst case winter and
summer temperatures, which are based on
weather observations collected from 1981 to 0
Energy Simulation Weather Files are used in
2006 by the Atmospheric Environment Service
energy models to help simulate the performance -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 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 31 32 33
at Environment Canada.
of a building over the course of a year.
• For summer, mechanical cooling systems Outdoor Air Temperature °C
Canadian Weather Year for Energy Calculation
are typically designed to the July 2.5%
(CWEC) files are used to represent a “typical”
temperature – in other words, only 2.5%
year of weather data. These files are generated
hours per year are expected to increase * Typical Number of Hours Based on 30 Years of Historical
by Environment Canada for a specific location
above this temperature. Weather Data (1984 -2014) Published in CWEC 2016.
based on 30 years of historical weather data
• For winter, heating equipment is typically
using the most typical results for each month An energy simulation weather file will contain temperature
designed to the January 1% temperature –
of the year. The original CWEC files used data data for all 8760 hours of the year for a given location, while
in other words, only 1% hours per year are design data only represent the hottest and coldest conditions
from 1959 to 1989, but were updated in 2016
expected to go below this temperature. for mechanical equipment sizing.
to reflect 1984 through 2014.
Modelling for a Future Climate 14BC ENERGY STEP CODE DESIGN GUIDE SUPPLEMENT S3 OVERHEATING AND AIR QUALITY MODELLING FOR A FUTURE CLIMATE SECTION S3-03.
03.2 Performing a Future Climate Analysis
Design teams can conduct future climate analysis
8
using available data on future weather projections
Sources of Future
and climate scenarios. Running multiple time Weather Files
periods and climate scenarios can help to give
6 RCP 8.5 CLIMATEDATA.CA
owners and design teams a better understanding of
Launched by the Government of Canada in
the potential impact of different design decisions. July 2019, this site allows users to search
for climate data by location, view interactive
Weather file projections are most often developed for the 2020s, climate data maps with detailed time series
4
Temperature Change (°C)
2050s and 2080s. graphs, and download datasets.
RCP 4.5
Climate scenarios are usually presented using three possible futures, WEATHERSHIFT.COM
or “Representative Concentration Pathways” that indicate the RCP 2.6
2 This site provides simple future weather
degree of climate change severity that we are likely to experience:
projections for major Canadian cities and
PCDS allows weather files to be uploaded and
• The Best-Case Scenario (RCP 2.6) assumes that we will
translated into future scenarios for a fee.
drastically reduce our GHG emissions and begin to remove
existing GHGs from the atmosphere. 0 PACIFIC CLIMATE IMPACTS CONSORTIUM
• The Stabilization Scenario (RCP 4.5) assumes that all PCIC is a leading organization researching
countries will undertake measures to mitigate emissions climate change and its impact to Canada’s
simultaneously and effectively. western regions. Their website provides access
-2 to a variety of practical tools and sources of
• The Worst-Case Scenario (RCP 8.5) assumes that we climate information.
will experience high population growth and relatively slow income 1950 2000 2050 2100
growth with modest rates of technological change and
energy intensity improvements.
Adapted from Figure SPM.7a from "Summary for Policymakers” by Climate Change 2013: The Physical Science Basis.
Lighter colour bands represent the range of potential temperature increases within a single scenario.
KEY TAKEAWAY
Even with ongoing efforts to reduce our carbon
emissions, changes in climate to 2050 are
guaranteed due to the inertia in the climate
system. At a minimum, building designers
should consider a 2050 climate scenario of
RCP 8.5. Even if the climate begins to stabilize
before 2050, this will improve resilience for
the lifespan of the building.
Performing a Future Climate Analysis 15BC ENERGY STEP CODE DESIGN GUIDE SUPPLEMENT S3 OVERHEATING AND AIR QUALITY MODELLING FOR A FUTURE CLIMATE SECTION S3-03.
Case Study: A Future Climate Analysis for a Mixed-Use Residential Building
A climate weather analysis was completed on a mixed-use residential and clinic facility in Vancouver to better understand the design strategies a specific project might need to reduce overheating. The analysis
compared the risk of overheating using CWEC 2016 data to the risk that might occur in 2050.
The study explored operable windows as a way of reducing the total number of To explore additional methods of passively cooling the building, a second analysis The results of these modelling exercises show that adding some form of
overheating hours. Under a CWEC 2016 climate, the model showed that operable explored the effectiveness of shading for the hottest rooms in the building. mechanical cooling will be necessary to avoid overheating in the 2050s.
windows reduce overheating hours from 2271 to 29, making them a good
passive cooling strategy. The study found that for these rooms, peak indoor temperatures can coincide with However, the addition of mechanical cooling in this analysis cause a spike in the
peak outdoor temperatures, and not the peak intensity of incoming solar gains. As building’s Total Energy Use Intensity (TEUI). This means that the project’s design
However, the warmer temperatures of the 2050s make operable windows far such, adding shading will not be sufficient in preventing overheating. As peak outdoor team will have to incorporate additional energy saving features in order to meet
less effective, pushing overheating hours above the BC Energy Step Code’s summer temperatures in the 2050s near 34°C, indoor temperatures in these suites both its TEUI and overheating targets.
allowable limit of 200 hours for the general population, and 20 hours for vulnerable will exceed the target indoor temperature of 28°C set by ASHRAE 55.
populations. The results of this study show that additional strategies are
necessary to cool the building.
Average Suite Summer Overheating Hours Level 6 SW Corner Suite Indoor and Outdoor Temperature Energy End Use Intensiy Breakdown
Operable versus Fixed Windows and Solar Radiation; July 23, 2050s Highlighting Cooling and Heat Rejection
140
3500 36 1000
Average Suite Summer Overheating Hours
3075 hours 34 900
120
Global Radiation (W/m2)
3000 800
2271 hours 4 kWh/m² 16 kWh/m²
32
2500
Temperature (°C) 700 100
Project CWEC2016 2050
30 600 Blended Project Project
Blended Blended
kWh/m2
80 116 kWh/m²
2000 28 500 114 kWh/m² 122 kWh/m²
26 400 60
1500
300 110 kWh/m² 106 kWh/m²
24 TEUI TEUI TEUI
1000 200 40 TARGET PASSES FAILS
22 100
500 20
239 hours 20 0
29 hours
0 12AM 4AM 8AM 12PM 4PM 8PM 12PM 0
Operable windows Fixed windows CWEC2016 2050
Outdoor Temperature (°C) Clinic Cooling Only Clinic & Residential Cooling
CWEC16 2050 Indoor Temperature (°C)
Global Solar Radiation (W/m2) Project Blended TEUI Target All Other End Uses
Cooling & Related End Uses Blended Results
METRIC: BCESC Overheating Hours METRIC: Peak Temperature in Southwest Suite METRIC: BCESC TEUI
PROJECT TARGET: < 200 hours, per BCESC PROJECT TARGET: < 28°C, per ASHRAE 55 PROJECT TARGET: 116 kWh/m2
CWEC 2016 RESULT: 29 hours 2050S RESULT: 34°C 2016 RESULT (NO COOLING): 114 kWh/m2
2050 RESULT: 239 hours 2050 RESULT (WITH COOLING): 122 kWh/m2
Performing a Future Climate Analysis 16BC ENERGY STEP CODE DESIGN GUIDE SUPPLEMENT S3 OVERHEATING AND AIR QUALITY SECTION S3-04.
SECTION 04.
.
Key Design
Strategies
04
04.0 Key Design Strategies
04.1 Passively Cool the Building
04.2 Use Shading to Block Solar Heat Gains
04.3 Cooling via Natural Ventilation
04.4 Couple Passive Cooling with Active Approaches
04.5 Add a Source of Cooling
04.6 Filter the Air
04.7 Include a Refuge Area into Building Design
17BC ENERGY STEP CODE DESIGN GUIDE SUPPLEMENT S3 OVERHEATING AND AIR QUALITY KEY DESIGN STRATEGIES SECTION S3-04.
04.0 Key Design Strategies +
12
H
IG
H
This section presents details on the key design strategies
-R
IS
11
E
M
necessary to mitigate air quality and overheating issues in
U
R
B
MURB. 10
9
High-Rise MURB 6
In this guide, High-Rise MURB refers to multi-unit residential buildings of six 8
5
storeys or higher, often designed and built using concrete construction techniques.
M
ID
-R
Such buildings usually consist of one to two storeys of commercial space at grade, 8
IS
E
4
M
U
with up to several dozen setback storeys of residential units above. Exclusively
R
B
residential high-rise MURBs often include common areas (e.g. lobbies) and shared- 7
3
use facilities (e.g. gyms and common rooms), alongside or in addition to ground-
level suites. 6
2
Mid-Rise MURB 5
Mid-Rise MURB refers to multi-unit residential buildings of three to six storeys, and 1
4
designed and built using wood-frame construction techniques. Mid-rise MURBs
can be configured with a concrete first storey and wood construction above. Mid- 3
rise MURBs can be residential only, or else host small businesses in the first and
second storeys. 2
Key Design Strategies
The strategies presented in this section represent some of the most effective
strategies to reduce the risk of indoor air quality and overheating issues that can
be applied in BC's Climate Zones 4 and 5. Lower Mainland (Climate Zone 4). 1
However, site conditions, the owners’ performance requirements, and many other
factors will affect what strategies are most appropriate for a given project. As such,
designers should consider a variety of strategies to determine the best response
to meet their specific needs.
Key Design Strategies 18BC ENERGY STEP CODE DESIGN GUIDE SUPPLEMENT S3 OVERHEATING AND AIR QUALITY KEY DESIGN STRATEGIES SECTION S3-04.
04.1 Passively Cool the Building
The use of passive cooling strategies is an important way to either reduce or remove heat from a space without increasing the building’s overall energy use.
Some passive strategies can be applied across an entire building’s design and should be considered in early stages of the design process for greatest impact, while others (such as adding vegetation)
can be added later on. Additional details on using passive design to increase energy efficiency can be found in the main body of the BC Energy Step Code Design Guide.
Building Shape and Massing Building Orientation
A simple shape and compact massing can help reduce heat losses in the winter. However, complex While a building’s orientation is often determined by the site’s size, shape and general constraints,
massing may provide better access to passive cooling strategies, such as operable windows and orientation can be optimized to balance energy performance and overheating.
self-shading from solar gains. Designers should explore means of maximizing building energy
efficiency through shape and massing, while considering the potential benefits of a particular Building orientation should maximize the south and north facades and minimize the east and west
geometry to mitigate overheating. facades. Windows and effective shading can then be optimized on south and north facades to
maximize solar gains for “free heating” in the winter, while blocking gains in the summer.
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19BC ENERGY STEP CODE DESIGN GUIDE SUPPLEMENT S3 OVERHEATING AND AIR QUALITY KEY DESIGN STRATEGIES SECTION S3-04.
Thermal Mass Window Design
Thermal mass refers to a material’s ability to absorb and store heat. Buildings with high thermal mass can absorb and store heat during Lower window-to-wall ratios can reduce solar gains in the summer while also reducing heating energy requirements
the day when temperatures are high, reducing cooling energy requirements. This heat is then released at night when temperatures are in the winter. To maximize control over heat gains, south and north facades should have higher window-to-wall ratios
cooler, and can be removed using passive strategies such as operable window or vents. than on the east and west facades.
While higher U-values help reduce winter heat losses, they can also retain heat in the summer, and should be used in
combination with other passive cooling strategies.
More than
50% WWR
KEY TAKEAWAY
Consider building-level passive cooling
strategies early on in the design process
to minimize overheating in passively-
cooled buildings, and reduce overall energy
consumption in mechanically-cooled buildings.
Passively Cool the Building 20BC ENERGY STEP CODE DESIGN GUIDE SUPPLEMENT S3 OVERHEATING AND AIR QUALITY KEY DESIGN STRATEGIES SECTION S3-04.
Cool Roofs
Roofs that are designed to reflect solar gains can help reduce the amount of heat let into the space, CASE STUDIES
partiuclarly in buildings that have a higher roof-to-floor area ratio. Designers should consider using
reflective materials and colours, proper insulation (to reduce downward heat transfer), and green The Impact of Orientation on Overheating
roofs with planted materials that absorb solar radiation. Cool roofs have the added benefit of
Credit: BC Housing and Horizon North Manufacturing
reducing local heat island effect and reducing the overheating potential for both the building and
its surrounding neighbourhood.
To assess the impact of a building’s orientation on overheating,
Focal Engineering modelled a modular housing building in Burnaby,
BC. The model assumed a 24% window-to-wall ratio (WWR) and
operable windows for passive cooling. The project was targeting
Step 3 of the BC Energy Step Code and so was required to meet
SOLAR OUTDOOR AIR
RADIATION TEMPERATURE a TEDI target of 30 kWh/m2/year. It also could not exceed 200
37ºC overheating hours per year.
The case study focused on a corner suite located on the top floor
and explored the impact of two orientations on overheating.
SO
• Run 1: West-facing suite
SO
RE LAR RE LAR
FL • Run 2: South-facing suite
10
FL
EC 50 EC
T
% TION % ION
HE
OU AT T
TS O The results of the exercise showed that the west-facing suite
IDE
HE
80 TO
AT E
(Run 1) experienced excessive overheating and a total of
R EM
BU AT
O P
ºC
T
HE TSID
O E
ILD TO
44
F R
247 overheating hours. In this scenario, additional cooling
R EM
S A
U
O P
U T
ING
ºC
T
O
O E
R U
TO
F R
FA R
S A
C E
AT G
U T
E
R U
HEILDIN or design modifications would be required to achieve the
FA R
C E
E
BU
project’s targets.
In contrast, the south-facing suite (Run 2) achieved a lower
overall risk of overheating at 156 overheating hours.
Run 1: West-facing suite Run 2: South-facing suite
Overall, the study demonstrates the importance of evaluating
all of BC Energy Step Code targets early on in the design process
when decisions such as orientation can still be impacted, to
ensure both occupant comfort and code compliance.
ADDITIONAL RESOURCES
Building Shape & Massing, Building Orientation, Building Massing, Windows Design: BC Energy Cool Roofs: Mitigating New York City’s Heat
Thermal Mass & Window Design: Vancouver Step Code Design Guide Island with Urban Forestry, Living Roofs and
Passive Design Toolkit, July 2009 Light Surfaces, October 2006
Passively Cool the Building 21BC ENERGY STEP CODE DESIGN GUIDE SUPPLEMENT S3 OVERHEATING AND AIR QUALITY KEY DESIGN STRATEGIES SECTION S3-04.
04.2 Use Shading to Block Solar Heat Gains
Incoming solar radiation, or solar gains, are a major contributor to overheating. Designs have to manage solar gains carefully to make sure that unwanted solar gains are minimized while ensuring that the
building can still harness useful solar gains in the winter for passive heating. A key way to achieve this balance is to use different shading strategies for each façade and for different spaces within the building.
ROODNI
Exterior Window Shades
Exterior shades are the most effective at passive MI HIG
D-R H-
cooling, as they prevent solar gains from entering the ISE AND
MU %01
space entirely. Designers can consider multiple types of RB dettimsnarT
ygrenE raloS
exterior window shading. taeH raloS latoT
tneiciffeoC niaG
PERFORATED SCREENS SEMI-TRANSPARENT SHADES
FIXED SHADES can block direct radiation from the sun in noissimE
mounted outside of a window or on can be used to block solar gains
debrosbA fo
ygrenE raloS
the summer while allowing passive heating in the winter.
a balcony can effectively block solar while allowing a view through to
gains, but will also reduce passive the outside.
OPERABLE SHADING can be adjusted as needed, heating potential in the winter and
either manually or automatically. will obstruct some of the view.
• Manually-operated shades give occupants more control,
but rely on occupants to be present in order to be effective.
• Automatically-controlled shades are more reliable in
preventing unwanted solar gains, but reduce occupants’
control over their space and are more expensive to install
and maintain.
While interior window shades are often used, they are less
effective as they allow solar gains to enter into the space,
causing the shades themselves to absorb heat. VERTICAL SHADES HORIZONTAL OVERHANGS
can be effective on any orientation; are best on the south façade as
however, they will reduce passive they block high angle summer sun
heating in the winter. while allowing low angle passive
solar heating in winter.
Use Shading to Block Solar Heat Gains 22BC ENERGY STEP CODE DESIGN GUIDE SUPPLEMENT S3 OVERHEATING AND AIR QUALITY KEY DESIGN STRATEGIES SECTION S3-04.
Vegetation Solar Heat Gain Coefficient
Exterior shading can be achieved by strategically selected Solar Heat Gain Coefficient (SHGC) is an important element in glazing selection
and designed vegetation. In the summer, deciduous trees and and can be optimized for each façade of a building. Selecting glazing with an
other foliage can provide shade to windows while allowing solar appropriate SHGC means finding the right balance between preventing overheating
gains to enter in the winter. Designers should consider the height and reducing a building’s thermal energy demand.
of the vegetation (both current and future) and its distance from
the building. A SHGC of 0.4 means that 40% of the solar heat gains that land on the outside
window surface enter into the space. A low SHGC reduces the risk of overheating.
While vegetation can effectively shade all building orientations, However, a SHGC lower than 0.28 starts to impact Visible Light Transmittance
it will require maintenance and will increase the building’s water (VLT), which can make spaces darker and require additional lighting energy —
usage, which will have more of an environmental impact as the adding more internal gains (heat) to the space. Conversely, a high SHGC allows
climate warms and more locations experience droughts It is more solar radiation to pass through the glazing, which reduces the building’s
recommended that drought-resistant, indigenous species be need for heating energy but can increase the risk of overheating.
considered wherever possible, with the possible addition of
grey and/or rainwater capture.
SUMMER SOUTH/WEST FACING FACADE SUMMER (South/West Facing Facade) WINTER (South/West Facing Facade)
OUTDOOR INDOOR
SUN
100% 40%
Solar Energy Transmitted
Solar Energy
Total Solar
Heat Gain
Coefficient
Reflected Emission of
Solar Energy Absorbed Solar Energy
SUMMER (South/West Facing Facade) WINTER SOUTH/WEST FACING FACADE WINTER (South/West Facing Facade)
Use Shading to Block Solar Heat Gains 23BC ENERGY STEP CODE DESIGN GUIDE SUPPLEMENT S3 OVERHEATING AND AIR QUALITY KEY DESIGN STRATEGIES SECTION S3-04.
Window Coatings Electrochromic Glazing Shading Strategies Comparison
Electrochromic glazing technology allows for
Window coatings, such as low-emissivity
automatic or manual control of a glazing tint
coatings, reduce the amount of radiation
and solar heat gain properties. These products
transferred through windows while allowing Fixed Manual Automatic Vegetation SHGC Window
have a similar effect to exterior automatically
light to pass through. External Shades Shades Selection Coatings
controlled operable shades. Shades
Livability
Aesthetic
No additional
maintenance required
OU Controllability
TDO
OR
No increase in need *
for indoor lighting
IND *
OO Glare control CASE STUDIES
R
LEGEND Good Better * Some SHGC reductions may impact visible light transmittance Shading in Vancouver’s
Olympic Village
2 3
Several of the Olympic Village’s buildings
Low-emissivity window Low-emissivity window feature diverse shading strategies. Of note are
coating on second surface coating on third surface
helps reflect summer heat helps reflect winter heat the automatically controlled shades that are
to the outside, reducing back into the interior mechanically raised and lowered in response to
solar gains in warmer space, helping to reduce
measured incoming solar gains. This strategy helps
months, helping reduce heat loss during colder
cooling costs. months and thereby to block solar heat gains when they are greatest,
KEY TAKEAWAY
reducing heating costs. and avoids relying on occupants to remember to
lower them. Shades are also semi-transparent so
• Install a reflective, cool roof to reflect heat away from the building
occupants can still enjoy an unobstructed view to
• Maximize glazing on the south façade and shade it appropriately to harness
False Creek and downtown.
solar gains when they’re wanted, while keeping east and west glazing low
• Select glazing with a low U-value and a SHGC that balances the need to prevent
Top The Brook at False Creek, Vancouver, BC
overheating (i.e. a low SHGC) with the need for free heating (i.e. a higher SHGC)
Bottom Semi-transparent shades from inside suite
Visible light passes
through into indoor
space
Use Shading to Block Solar Heat Gains 24BC ENERGY STEP CODE DESIGN GUIDE SUPPLEMENT S3 OVERHEATING AND AIR QUALITY KEY DESIGN STRATEGIES SECTION S3-04.
04.3 Cooling via Natural Ventilation
Once other passive design CONTROL POSITION
Automatic controls can be programmed in The vertical position of openable windows and
strategies have been explored, the
common areas to open windows and/or vents vents should be considered to mitigate the risk
risk of overheating can be reduced based on a schedule or sensed input. Manual of unintended access on the lower floors or fall
even further by removing heat window controls should come with instructions hazards on the upper floors.
for occupants on when to open or close
gains from inside a building using windows to maximize the potential of natural SIZE
methods of natural ventilation. ventilation and cooling. The size a window, the depth of its opening,
and any restrictions on how far they can open
OUTSIDE CONDITIONS should all take Code requirements and safety
Natural ventilation is the process Occupants will be less likely to open windows concerns considerations into account. Small
of increasing the flow of outdoor if exterior conditions are unfavourable, such as operable windows or vents that are restricted
noise, poor air quality (e.g. noise, smoke, dust may be ineffective in providing natural
air into a space through openings or smells) or uncomfortable conditions (high ventilation and cooling.
in the building envelope, such as temperatures or humidity).
windows. Using natural ventilation
OPERATION AT NIGHT
help reduce a building’s reliance Nighttime ventilation allows buildings to be
on mechanical systems to provide passively pre-cooled in preparation for the next
day. Openings and vents should be designed
cooling and help occupants achieve
to restrict access by people or animals where
thermal comfort for most of the necessary, and located away from sources of
allergens and pollutants.
Key issues to keep in
year. Many occupants also like mind when designing for
being able to open a window to EFFICIENCY
operable windows:
adjust their indoor environment. Operable windows often have a higher • Indoor and outdoor air temperatures
(worse) U-value than fixed windows and can will be similar when windows are open,
decrease building airtightness. Designers which can cause thermal comfort issues
The most effective way to achieve natural should look for windows with lower overall at higher temperatures, particularly as the
ventilation is through the use of operable U-values, consider the effectiveness of the climate warms.
windows or vents in the building envelope. window seal, and look for a multi-point
There are several aspects that need to be locking mechanism to ensure airtightness. • Air quality can become a concern when using
considered to ensure that they are as operable windows for cooling, since the air
effective as possible. LOCATION isn’t filtered before entering the room.
The location of the residential unit, elevation
and height, will impact the size of opening • Building occupants may be less likely to
required, especially if only single-sided open their windows if they are located in
ventilation. Wind pressure will have a greater a noisy area, reducing the effectiveness
impact as height increases and external gains of the strategy.
can vary across a single elevation due to
shading from neighbouring buildings.
Cooling via Natural Ventilation 25BC ENERGY STEP CODE DESIGN GUIDE SUPPLEMENT S3 OVERHEATING AND AIR QUALITY KEY DESIGN STRATEGIES SECTION S3-04.
CASE STUDIES
acility in BC’s Lower Mainland was modelled to explore the impact of
The Impact of Operable Windows
ating. As its original design resulted in 2,788 Overheating hours (far
BC Housing and Nanaimo Affordable Housing Society
ade and modelled to see if they made a difference.
A concrete and wood frame affordable senior housing facility was modelled to
southwest facing
explore thewindows. This
impact of operable resulted
windows in a noticeable
on the building’s reduction in
potential for overheating.
s. As its original design resulted in 2,788 overheating hours (far above the
200-hour target), two passive cooling strategies were modelled to see if they
made a difference.
dows were included into the analysis. Windows were assumed to be
First, horizontal and vertical shades were added to several southeast and
o open them), when room temperatures exceeded 23C, and when the
southwest facing windows. This resulted in a noticeable reduction in thermal
eratures. This resulted
discomfort, down toin a significant
1,864 reduction
overheating hours.To inoverheating,
further reduce overheating, down
operable windows were then included. Windows were assumed to be open
between 6am-10pm (when occupants are awake to open them), when room
temperatures exceeded 23°C, and when the outside air temperature was lower
than indoor air temperatures. This resulted in a significant reduction in
overheating, down to only 162 overheating hours.
Above Low Hammond Rowe Architects (LHRA)
Cooling via Natural Ventilation 26You can also read
