A Critical Review of Green Retrofit Design

Abstract

Green retrofit design (GRD) has two major aims: to improve energy efficiency and reduce carbon emissions in existing buildings that are to be sustainably retrofitted. The gap between architects and engineers is evident at the pre-design stage as architects understand little about energy models while engineers use them to conserve energy. However, the goal for both architects and engineers is to develop sustainable building forms that are sensitive to the environment and conserve energy. This paper presents the current technology development for GRD and provides a decision support model to help architects get involved in reducing carbon emissions at the pre-design stage. The GRD process is demonstrated and discussed from the aspect of retrofitting a commercial building and different standards used to verify the results. The aim of this research is to provide a decision-making framework for architects to use at the pre-design stage so as to enhance GRD energy conservation, and thereby contribute to the goal of sustainability. Building information modeling (BIM) inter-operability is also discussed as part of the technology development trend.

Full text

A Critical Review of Green Retrofit Design
Shanshan BU1 and Geoffrey Q.P. SHEN2
1Ph.D. Candidate, Department of Building and Real Estate, The Hong Kong
Polytechnic University, Hong Kong, PH (852) 27664308, FAX (852) 27645131,
Email: shanshan.bu@connect.polyu.hk
2Professor, Department of Building and Real Estate, The Hong Kong Polytechnic
University, Hong Kong, PH (852) 27665817, FAX (852) 27645131, Email:
geoffrey.shen@polyu.edu.hk
ABSTRACT
Green retrofit design (GRD) has two major aims, which are to improve
energy efficiency and reduce carbon emissions in existing buildings that are to be
sustainably retrofitted. The gap between architects and engineers is evident at the
pre-design stage as architects understand little about energy models while engineers
use them to conserve energy. However, the goal for both architects and engineers is
to develop sustainable building forms that are sensitive to the environment and
conserve energy. This paper presents the current technology development for GRD
and provides a decision support model to help architects get involved in reducing
carbon emissions at the pre-design stage. The GRD process is demonstrated and
discussed from the aspect of retrofitting a commercial building and different
standards used to verify the results. The aim of this research is to provide a decision
making framework for architects to use at the pre-design stage so as to enhance GRD
energy conservation, and thereby contribute to the goal of sustainability. Building
information modeling (BIM) inter-operability is also discussed as part of the
technology development trend.
INTRODUCTION
Differernt countries have their own aims for reducing carbon emissions when
retrofitting existing buldings. The U.S. Energy Information Administration’s
Commercial Buildings Energy Consumption Survey report (CBECS 2003) indicates
that between 1983 and 2003 there was no real improvement in the aggregate
commercial building stock, and that buildings less than 100,000 square feet (9,290
square meters) accounted for 65% of the commercial building floor space. According
to China’s Twelfth Five Year Plan for Energy Conservation 2012, the potential
building energy conservation market is extremely large and the building energy
conservation range is expanding. During the Twelfth Five Year period, 570 million
square meters of buildings will be in need of energy retrofitting. Before the year
2020, project investment for energy conservation of these buildings will be at least
RMB 1.5 trillion (THUBERC 2010). This means that there will be a huge demand
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for energy retrofitting of existing builings in China. So too in Hong Kong, with the
‘ten major infrastructure projects’ proposed in the government’s 2007/2008 Policy
Address, planning and control strategies for emissions reduction is needed in the
design process.
In his study of energy efficient architecture and building systems, Ali (2008)
observed that “no humanly created environment can survive without the
contributions of the larger natural environment or ecological systems” and
“Sustainable design is a response to awareness and not a prescriptive formula for
survival”. The roadmap for green retrofit design (GRD) proposed by Rhoads (2010),
separates the retrofit design process into the following seven steps: Define corporate
retrofit goals； Designate roles & responsibilities；Prioritize building portfolio；
Agree financing arrangements； Select appropriate technology；Delivery ；Evaluate.
GRD PROCESS
Current and target energy consumption and CO2 emissions in China. From
2000 to 2010, energy consumption for China’s building sector doubled from 289
million tonnes coal equivalent (tce) to 677 million tce as the building area increased
from 27.7 billion square meters to 45.3 billion square meters. Under the current
energy structure, the national supply of primary energy in China is about 32 billion
tce and the consumption limit is 4.1 billion tce predicted to rise to 4.3 billion tce by
2015 (Jiang 2012).
By 2010, the demand for energy was so great that China’s total carbon emission
was 30.49 billion tons and the country was responsible for 28% of the world’s carbon
emissions. By 2020, CO2 emissions are predicted to reach 40 billion tons. However, in
response to pressure from the global community for every country to do its part in
reducing emissions, the target is that by 2050 the total CO2 emissions in China will be
reduced to 48%~72% of the amount in 2000.
Existing green building design (GBD) and green retrofit design (GRD) process.
(1) Green Building Design (GBD) Process. Green building design (GBD) is described
as a ‘front-loading’ process that treats the building design, the surrounding landscape
and the entire community as a whole system (Krygiel 2008). Sustainable design starts
with establishing a baseline building mass and volume using building information
modeling (BIM) to compare the pros and cons of alternative building shapes. The
building forms to be compared need to have the same basic values and the same
amount of occupancy space. In the United State (US), considerations at the design
stage involves making comparisons with the same number of users, operating schedule,
lighting, HVAC, and envelope system based on ASHRAE Standards (ASHRAE 2008;
2012a; 2012b). For the most sustainable solutions in the fastest way, schemes can be
simulated by exporting assumptions (HVAC system, glazing properties, exterior walls,
etc.) to a BIM energy-analysis software program (Krygiel 2008).
There is relatively little research related to GRD optimization compared to
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studies on green buildings and energy conservation. Research towards design
optimization in green building using multi-objective genetic algorithms is employed
to find optimal solutions for green building design (Wang et al. 2005; Zmeureanu et
al. 2005). Life cycle analysis methodology is employed for economical and
environmental criteria. GRD combines the design processes with retrofitting,
renovation and refurbishment when considering client’s a client’s needs, policy
driven motivations, and construction behaviour (Kissock 2003; Wang et al. 2005;
Zmeureanu et al. 2005).
(2) Generic GRD Process. Energy-efficient design is seen as the biggest
contribution to the GRD process in terms of improving long-term operating costs and
protecting the environment. GRD is labeled as ‘energy-conscious’ ‘passive’ or
‘bioclimatic’ depending on how the design meets the functional, environmental, and
comfort needs of occupants. Energy-saving tasks profile existing renovation
conditions, and conduct energy and economic analysis throughout the design process.
The steps in energy-efficient design Prowler (2000) described are in three scales of
effort as modest effort, intermediate effort and large effort, taking human effort from
person-days to person-months (Power 2007).
When designing for GRD, a building’s existing condition is considered for
energy modeling, variation benefits, and compliance with legislative requirements.
GRD should provide technology solutions to the energy issues of the existing
building, such as providing rain water reuse technology, air conditioning and heating
energy saving technology, shading technology, roof ground insulation technology,
and lighting system modifications (Roahds 2010). Investigation unit building result,
combined with the local climate conditions, establish the reasonable economy, would
be helpful for saving energy and climate protection energy-saving reform plan
comprehensive, and retrofit of special design. Design goal is guaranteed to meet
indoor thermal comfort need, under the premise that building energy consumption
should satisfy the existing heating local residential building energy-efficient design
standards in advance.
Commercial sector GRD process. The Energy Service Company’s (ESCO)
process for the development and execution of a commercial sector retrofit project is
a typical approach that comprises four phases (See Figure 1).
Discovery Verification ExecutionQualification
Figure 1.ESCO process for a retrofit project.
In Phase 1, the energy service company investigates credit worthiness, capital
constraints, energy cost savings potential, building lease structures, client goals, and
other basic elements that determine the viability of a retrofit project. These
considerations will result in a memorandum of understanding between the energy
company and the client at the enrolment stage.
In Phase 2, data are collected, including interviews, drawings and specs, past
projects, and utility bills, which will form a preliminary report at the assessment
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stage. The metrics provided on each measure include capital cost, energy savings,
energy savings, maintenance savings, simple payback, return on investment, net
present value (NPV), and internal rate of return (IRR) (Fluhrer 2010). At the end of
Phase 2, a project development agreement should be presented to the client.
In Phase 3 and 4, verification and execution respectively, engineering capital
costs and energy and maintenance savings are detailed as part of the cost proposal
and feasibility study at the Action Plan stage and Project Proposal stage.
The case for choosing demolition or re-build varies in different countries for
a number of reasons. In Asian countries such as Singapore and Hong Kong, some
buildings are demolished and rebuild after only 10 to 15 years. Uncertain economic
times and environmental awareness make the choice of retrofit and refurbish more
obvious to meet future sustainability. Models for the retrofit process involving
different levels of high technology and the involvement of different sectors is worthy
for discussion. According to ASHRAE’s report ‘An architect’s guide to integrating
energy modeling in the design process’, energy modeling is not only a technology
topic but also a design topic.
The definition of high technology varies according to whether the techniques
involved are industry-based, firm-based, product-based or life-cycle-based
(Steemhuis 2006). For example, in the US, industry-based high technology is defined
by SIC (Standard Industry Code) codes, one indicator of which is the intensity of
research and development (R&D). High technology from a firm-based aspect would
focus more on the company level rather than the entire industry.
Product-based high technology, such as retrofit, is measured by the amount of
R&D invested for creating products and the investment in maintenance and plants.
Life-cycle-based high technology continuously and quickly keeps up to date, with a
cradle-to-grave approach for assessing high tech industrial systems. For developing a
reliable model for the retrofit process, the design process must consider manufacture,
use, and maintenance For re-design, the building process should involve determining
the optimal engineering for GRD before engaging the architect (AIA 2012).
Another concept is known as “eco-renovation”, which refers to retrofitting
activities aimed at achieving carbon reductions of over 60% compared with
pre-renovation emissions (Fawcett 2011).
GRD process for other sectors. Doukas et al. (2009) developed building energy
management system (BEMS) to support decision makers for the existing office
building in Greece based on the loads, demands and user requirements in the energy
auditors and building administration management. Theodoridou et al. (2012)
proposed an integrated assessment tool in Greece using the Geographical
Information System (GIS) for the existing urban building stock with a special focus
on residential buildings. The methodology is designed to be flexible for different city
structures, which on a macro-economic scale considers the evaluation parameters of
renewable energy sources, building envelope and carbon emissions. Kolokotsa et al.
(2009), developed an energy efficiency management system based on strategies for
building sustainability that include considerations of building codes, passive energy
design, policy packages, and building certification schemes.
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Energy intensity for commercial buildings. Existing policies and incentives for
saving energy in buildings mainly calculate energy consumption by electricity usage.
As the Energy Efficiency & Renewable Energy (EERE) department in the US
mentioned in the building energy data book in 2012, commercial buildings consume
around 20% of the total energy consumed with office space and educational facilities
representing half of it. Energy efficiency opportunities for manufacturing are
relatively fewer than the facility-related energy requirements for heating, ventilating
and air conditioning (HVAC), lighting and office equipment that are the main
consumers of energy (EPA 2007). The common consensus of GRD research is that
energy-intensive industries, including the commercial sector, seek to control energy
costs by investing in energy efficiency (EERE 2012). Public programs affect
decision-making for building retrofit because policy incentives come from such
factors as pre-design analysis assumptions, government pressure, cooperation cycle,
budget execution, and construction behavior (see Figure 2).
Pre-design
analysis
assumption
Factors influence quality of GRD
Technical design in the
pre-design stage
Cooperation of different
sectors Behaviours in Construction
Numerical
algorithms
Owner &User
group with
aspects on using
Architects & Engineer
& Speciality (A & E
& S) on design
Inter-
cooperation
Considerations for
Energy consumption
in construction
Feedback
and revise
Figure 2.Factors influencing GRD quality.
BIM information flow in the early stages of GRD. (1) Development of Design
Modeling. In a traditional design process, parametric models are built at the initial
design stage and layers generated for subsequent stages. These layers of design for
models require more information than architect drawings can provide (Eastman,
2011). When developing a collaborated BIM model, the architectural model and
consultant/subcontractor models are first operationally connected through the BIM’s
export link and then analyzed to identify such things as construction sequencing and
material delivery conditions. The next level of the BIM design process involves
input from civil engineers who design the complex operations. At this stage the BIM
process would be slow because the focus would be on supplementing the architects’
design with more detailed information as shown in Figure 3 (Eastman 2011).
CAD
Platform Assembling
Modeling Parametric
Object Modeling
Parametric
solid modeling 
Figure 3.Design modeling development.
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For supporting activities such as sustainability, the model information
includes performance specification for HVAC and other facility operation equipment.
When it comes to GRD, some uncoordinated project information may be required
from the owner to be pieceed together by the engineer. Using BIM as a tool would
benefit the inter-cooperation between the owner-user group and the GRD
architecture, engineering and speciality (AE&S) group, and merge the gap between
architect and engineer at the pre-design stage.
(2) Elements and components in BIM information flow for GRD. Building
programming as part of the information flow involves several elements and
components. Take building SMART as an example (William 2010; 2012):
Pre-program requirements; Program functions (R1); Program space requirements
(R2); Program system requirements (R3); Program equipment requirements (R4).
Energy analysis for GRD is done on a 3D unfolded model. Ecotect Analysis
and Green Building Studio provide improved design insight through whole building
energy, water and carbon-emission analysis, and by helping architects and designers
to maximize building economic and environmental performance. The tools are
compatible with Autodesk design software as well as software from other industry
providers through the Green Building XML (gbXML) scheme and can now be
directly accessed from within the Revit platform for BIM with a new plug-in
available for download. Autodesk has also developed simulation Computational
Fluid Dynamics (CFD) and 3ds Max Design building analysis tools. Ecotect
Analysis and Green Building Studio are more popular for energy analysis of new
buildings, while Energy Plus and DeST are normally used for existing buildings.
AIA (American Institute of Architects) introduced Building SMART in June 2005
for integrating 3D object-based modeling and BIM for the AEC industry. The
Building SMART community share with the building information circle from the
open standards (IFC.IDC and IFD) for the architectural design and project practice.
The Information Delivery Manual (IDM 2010) is used at the concept design phase
for energy analysis.
CONCLUSIONS
To sum up, GRD’s main technical measures are: Design and enhanced
maintenance of energy saving insulation; Development of energy-saving techniques,
such as cold storage technology and cooling tower technology; Maintenance and
management of energy saving air conditioning systems; Renewable energy; Indoor
environment enhancement.
In order to realize the strategy of sustainable development, it is essential to
design and build for energy efficiency. As long as national conditions and the actual
site situation are taken into account, comprehensive use of various energy saving
measures and a reasonable economic plan, will produce remarkable energy saving
results for GRD buildings. Information flow for GRD in BIM would depend on the
current information available for the existing building and the design optimization
comparisons. Information exchange for different sectors in each step of the early
design stage influnces the GRD quality; future research may want to explore the
effects of such influences.
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ACKNOWLEDGMENTS
This research is funded by the National Natural Science Foundation of China
(NSFC). A debt of gratitude is due to the first author’s former supervisor, Dr. Ren
Zhaomin, who inspired this research but who sadly passed away in January 2013
after a battle with cancer. Gratitude is also due to Professor Chimay Anumba of the
Computer Integrated Construction Research Program (CIC) at Penn State University,
and to Dr. Andy Wong of the Department of Building and Real Estate at The Hong
Kong Polytechnic University for their guidance and support.
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