Course Development and Delivery on
Energy Audits
Ecole Polytechnique de Tunisie (EPT)
Tunisia
Visit
Report
Moncef Krarti, PhD, PE
University of Colorado at
Boulder
Summary
Dr. Moncef Krarti of the
·
Review of basic
tools to analyze and evaluate building energy systems including computer
simulation methods and engineering economics.
·
Overview of
state-of-the-art methods to estimate thermal comfort and indoor air quality in
buildings.
·
Detailed
presentation of energy-efficient buildings systems including envelop,
electrical, and secondary and primary HVAC systems commonly used in commercial
buildings.
·
Simplified methods
to estimate the energy savings incurred from selected and proven retrofit
measures of building energy systems.
·
Site visit of the
energy systems (including the mechanical room) of the EPT
building.
·
Hands-on training
sessions of whole building simulation tool (VisualDOE)
to model energy systems for the EPT building.
In addition, a group project has been performed by EPT
students to audit energy systems of various buildings of EPT (residential
apartments, administrative offices, and classrooms). Each group has prepared a
final report and a power-point presentation to summarize the findings of their
energy audit.
Course Outline
Activities
The content of the course is outline in Table
1. The details of the course contents are provided in Appendix A. The course is
delivered in session blocks of 4 hours distributed through two
weeks.
Table 1:
Outline for the course
|
Day |
Session 1 (2 hours) |
Session 2 (2 hours) |
|
Day-1 |
Introduction to Energy
Analysis and Energy Audit |
Overview of economic
analysis of energy efficiency measures |
|
Day-2
|
Introduction to
State-of-the-art Computer Simulation and Screening
Tools |
Energy Audit of Building
Envelope Systems and related in-Situ Testing
Techniques |
|
Day-3 |
Energy Audit of
Electrical Systems. |
Discussion of Benefits
of Improving Power Quality. |
|
Day-4
|
Energy audit of HVAC
secondary systems |
Energy audit of HVAC
primary systems |
|
Day-5 |
Hands-on training on a
building simulation tool (VisualDoe) |
Site Visit of the
|
A detailed
description of the contents of the course is provided in the section Course
Contents (see Appendix A). The teaching materials consist of the following
resources:
(i)
A teaching manual
developed specifically for this course. Each trainee was handed one copy of the
manual. The manual is prepared based on the book described
below.
(ii)
A textbook
entitled ““Energy Audit of Building Systems: An Engineering Approach”
written by the IC (M. Krarti) and published by CRC
Press,
(iii)
A series of
PowerPoint presentations used during the lectures. Electronic copies of some of
these presentations are available on the web site of the project and on Prof.
Krarti web page (http://civil.colorado.edu/~krarti).
(iv)
A training guide
for VisualDOE (see appendix B)
(v)
A list of tasks to
be performed by the trainees during and after the site-visit of the
Course
Delivery
The course Energy
Audit of Building Systems has been delivered to 26 students, all from EPT. A
slightly modified course has been also offered to about 7 students from another
school (ENIT, Ecole Nationale d’Ingenieurs de
Table 2: Listing of students and
their group project assignment
|
Group No. (list of
Students) |
Group Assignment
|
|
GROUP A : Badri Abdessalem, Ben Abdallah Moez, Drine
Okba, Ellili Slim Akram, Ganmi Wajih, Krichen Moez, Mnija Wassim,
Ould
Habib Abdefateh, Ounayssa Haytham |
Audit the
residential apartments of EPT. In addition to the site visit, the students
performed the utility data analysis as well as a computer simulation of
the apartments. |
|
GROUP B: Bazine Rochdi, Kallel Mériam, Layeb Safa, Dridi Houda, Kacem Radhia, Ayadi Nadia, Mrabet Sarra, Jomâa Moez , Missaoui Walid |
Audit of the
administrative building of EPT. The students carried out a site visit,
utility data analysis, and computer
simulation. |
|
GROUP C:
Daoud Anis, Chaari Mohamed, Saied Chedly, Ben
Salah Mohamed, Khmiri
Mohamed Ali, Jammoussi Hanen, Gassem Amine, Dhouib Mohamed Ayoub, Triki Mahdi |
Audit of the
classrooms of EPT. The students performed some measurements of indoor
temperature and relative humidity, inspected the mechanical equipment for
the HVAC system, and carried a computer simulation of the
classrooms. |
Figure 1: Students, members of Group A, who audited the
residential apartments of EPT.
Figure 2: Students, members of Group B, who audited the
administrative offices of EPT.
Figure 3: Students, members of Group C, who audited the
classrooms of EPT.
The course was delivered using both lectures
and hands-on training sessions. The lectures were delivered in a relatively
large auditorium equipped with all the needed audio-visual devices (overhead
projector, LCD projector, and a TV). During the lectures, some powerpoint presentations were used
to showcase the energy auditing procedure for selected case-studies. The
hands-on training sessions took place in a computer room equipped with Pentium
III computers.
Recommendations for Future Delivery
of the Course
In summary, Prof.
Krarti has successfully delivered the short course on
energy audit of building systems. Future delivery of the course should follow
the same teaching format and spirit with a special emphasis on hands-on
training.
Based on the first
offering of the course, Prof. Krarti has the following
recommendations for future delivery of the course at EPT:
- The current of
the format of the course should be followed with some minor adjustment
depending on the number of students and availability of computers. In
particular, it is recommended that sufficient number of computers should be
made available during the course period (it is recommended one computer per
two students).
- For the group
project, it would be better to assign a different building for each group to
audit. With different buildings, the students would get access to different
types of building energy systems.
Moreover, it is recommended that more coordination between the
responsible staff of the audited buildings and the instructors should be made
in future delivery of the course.
- For the course to
be effective, the number of students should not exceed 20 people. With a
higher number, it will be difficult to carry out smoothly the group project as
well as the training sessions for the computer simulation
tool.
- The focus of the
lectures should be hands-on engineering principles rather than a review of
engineering fundamentals. EPT students are generally good in theoretical
concepts but lack practical training.
APPENDIX
A
COURSE
CONTENTS
The topics to be
discussed during the short course are outlined below:
DAY 1:
Introduction to Energy Analysis
and Energy Audit:
§
General procedures
for energy management are presented including walk-through, detailed energy
audit, energy commissioning, and building energy rating.
§
Energy efficiency
measures and advanced energy management techniques commonly considered to improve the energy performance of
buildings.
§
Case study of an
energy audit conducted on a commercial building in
Overview of Energy Analysis of
Energy Efficiency Measures
§
Discussion of
common economic analysis methods used to determine the cost-effectiveness of
energy efficiency measures.
§
Presentation of
calculation procedures suitable for Life-Cycle Cost (LCC) analysis.
§
Introduction to
BLCC tool (a computer software available for free from
the US Department of Energy).
DAY 2:
Introduction of Computer
Simulation Tools
§
Discussion of
several computer simulation tools suitable for energy analysis of
buildings.
§
Detailed
presentation of state-of-the art simulation tools including VisualDOE, Energy10, and EnergyPlus.
§
Introduction to
energy analysis tools based on inverse models such as artificial neural
networks.
Energy Audit of Building
Envelope Systems:
§
Presentation of
graphical methods to determine the overall building load coefficient from
utility data.
§
Estimation of
energy savings using simplified methods for selected measures such as adding
thermal insulation and improving the air-tightness of building
envelope.
§
Discussion of in-situ tests used to
determine the infiltration rates and leakage areas for both residential and
commercial buildings.
DAY 3:
Energy Audit of Electrical
Systems and Power Quality Improvements
§
Discussion of easy
to implement energy efficiency measures for lighting, motors, and electrical
distribution systems including transformers and wires.
§
Presentation of
procedures of measuring and improving power quality for buildings due to low
power factor and/or high harmonics (typically caused by electronic equipment).
§
Discussion of
experimental tests suitable for evaluating energy use of electrical systems and
for identifying any power quality problems.
§
Calculation of
energy and cost savings due to improvements in electrical systems performance
and power quality.
DAY 4:
Energy Audit of Heating
Ventilating and Air Conditioning (HVAC) Secondary and Primary
Systems:
§
Discussion of the
benefits of various HVAC systems in reducing energy use.
§
Presentation of
selected energy efficiency measures to operate HVAC systems including better
controls, and improved maintenance procedures.
§
Estimation of
energy and cost savings due to better controls and operating HVAC systems
including air handling units as well as boilers and chillers.
§
Presentation of
in-situ testing procedures to determine the energy performance of various HVAC
systems.
DAY 5:
Discussion of Advanced
Technologies
§
Presentation of the
benefits of thermal energy storage (TES) systems in reducing demand costs. In
particular, optimal control strategies for TES systems will be discussed.
§
Discussion of heat
recovery systems and their cost-effectiveness for various
applications.
§
Overview of
cogeneration systems and their feasibility in commercial and institutional
buildings.
§
Presentation of
energy efficient cooling systems including passive cooling and desiccant cooling
systems.
Introduction of Energy Savings
Verification and Measuring Methods
§
Discussion of the
types and the benefits for energy performance contracting approaches.
§
Presentation of accepted protocols for
verifying and measuring energy savings due to the implementation of energy
efficiency measures in existing buildings.
Appendix
B
This
appendix includes the training material for VisualDOE,
a computer simulation tool, used during the short class.
TRAINING
SESSION NO. 1
(1) Use of Custom Block
Editor:
The Custom Block Editor allows the creation of blocks with user-defined
shape. It should be noted that a block is a set of rooms (or zones) of similar
characteristics (floor-to-floor height and space conditions). Before you can
perform the tasks listed below, review the various features of the Custom Block
Editor provided as part of this lab session 1.
a.
By using a new file and SI unit template
(note that the IP unit template is the default), create a block of four rooms
with only the rectangular shaped polygon as shown in Figure 1. If you wish you
the file with the custom block. However, there is no need to continue the input
procedure for this block.
b.
Following the same as step a., create a block
of one room using the irregular shaped polygon as shown in Figure 2.
Figure 1: A Block with four rooms created by the Custom Block Editor using the
rectangular polygon.
Figure 2: A Block with one room created by the Custom Block Editor using the
irregularly shaped polygon.
(2) Running Alternative Measures with VisualDOE
VisualDoe allows the user to run several alternatives in the same time. To illustrate this feature, use the existing file “Small Office.gph” and run all the alternatives. First, check how each alternative is modeled (in particular Natural Ventilation and Daylighting). Then, Discuss if the results make sense to you by plotting the monthly electrical energy use in the same graph.
Add a new alternative by modeling the HVAc
system as fan coil. Compare the energy use of the new alternative with that of
the base case.
TRAINING
SESSION NO. 2
(1) Effect of Windows on Energy
Use
In this part of the lab, we will try to see how to model a simple building box and determine the effect of adding various windows to this building. After starting VisualDoe, use the SI template to create a new file (i.e., project). Then add two openings “3X5.5 single clear” and “6x8 single clear” to the project library for openings using the Organizer screen. Then, proceed as follows:
1- Create a VisualDoe model of 30 m x 30 m x 4
m building (a box) with no window conditioned by a Constant Volume system using
the
2- Using the Alternative
screen, create the following alternatives
a.
One window (6x8 single clear) is added only
in the front and rear façades (use the screen Façade and select “Custom Façade”
option and then edit the façade using the Façade Editor screen (note that the
Façade Editor is similar to the Custom Block Editor).
b.
Bay-type windows (3x5.5 clear single) added
to all the four facades (use the screen Façade and select
“
3- Run the base case and the two alternatives for the box building and compare the electrical energy uses. Interpret the results and determine the impact of adding windows to the building energy use.
(2) Effect of Daylighting
on Electrical Building Energy
Use
Using the same box building file, add another alternative to model a daylighting option when the facades have the bay-type windows (see part 1 above). To model daylighting using VisualDoe, go to the Room screen. Then, for each perimeter room (Room_1 to Room_4), change the setting for “Daylight Control” option to “Dimming” and the luminance level to “250” (in Lux) and Control Fraction: to 0.8 for both sensors (sensor 1 and sensor 2).
Run the new alternative and discuss the results (compare with the base case and alternatives simulated in part 1).
Try to view the location of the daylight sensors using the Show 3D View feature (make sure to select Daylight Sensors and to check off Roofs).
(3) Adding Similar Floors to a
First, open the file you just created for the box building. Make sure you have only one base case with no Alternatives (delete Alternatives if there are any). Make sure, the model in “box.gph” runs with no problem. Then, create an alternative (you can call this alternative “2-levels”) and add another similar floor on top of the existing building using the Edit Screen and the options “Copy Block” and “Paste Block”. Run this alternative and compare with the base case.
(4) Adding New Materials and Construction
Types
Using any VisualDOE input file (start a new file if you do have one available in your input files) with an SI template, define new materials (for instance, Marble with a thickness 4 cm, a thermal conductivity of 2.2 W/m2.K, a heat capacity of 0.84 kJ/kg.K, and a density of 2000 kg/m3 and a Plaster with a thickness of 1.5 cm, a conductivity of 0.35 W/m2.K, a specific heat of 0.83 kJ/kg.K, and a density of 700 kg/m3).
To add new Materials to the existing VisualDOE library, use the Organizer Screen and select “Materials”. Then proceed by selecting the material type, add new material, rename, and edit. You should then a get a screen as shown in Figure 5 where you can input the various parameters.
Once you added all
the desired materials, you can build a construction type (for instance, marble +
plaster) using the Construction Editor as shown in Figure 6.
Figure 5: Screen for the Material Editor.
(5) Modeling Unconditioned Spaces using VisualDOE
DOE-2.1 assumes a constant temperature inside each space during load calculations in the LOADS module. The actual indoor temperature is estimated in the SYSTEMS module. Therefore, even if the building is unconditioned, a HVAC system has to be modeled. The rule is that each zone (i.e., room or space) has to be served by one and only one system. To properly model the indoor temperature variation, it is therefore important to understand the types of systems that DOE-2.1E (i.e., VisualDOE) can model. The DOE-2 BDL Summary Book provides a list of HAVC systems that can be modeled (see page 62 and subsequent pages 63-113 for more specific Commands that can be applied to each system). The user has to consult the Reference manual for detailed description of each HVAC system and its capability.
Figure 6: Screen for the Construction Editor.
To model a system with no heating capability (thus building that cannot be heated), several systems and options can be considered. Some options can be implemented using VisualDoe but some cannot and DOE-2.1E has to be used.
One approach to trick VisualDoe to model unconditioned building is to use a UNIT VENTILATOR system (no cooling capability). Model this system for the box building using an alternative that you can call “unconditioned-1”.
What other systems can be considered?
TRAINING
SESSION NO. 3
HVAC
Systems
Background:
To condition
buildings, several heating, ventilating, and air conditioning (HVAC) systems can
be used. For residential buildings, window air conditioners or split systems are
commonly used for cooling especially in hot climates. For commercial buildings,
variable air volume and/or heat pumps are more energy-efficient than constant
volume systems. VisualDOE/DOE-2.1E
can be useful to design and evaluate the best HVAC system suitable for a given
building.
1-
Specific Lab
Tasks:
The box model
(created in the first session) will be used for evaluating selected measures
using VisualDOE.
VisualDOE
Analysis:
1- Define the base case for the box model with typical office building cooling set-points. The HVAC system is a Constant Volume system. Run this base case and check the energy-use and indoor temperatures in January and July in all the rooms (from the Diagnostics reports).
2- Define an alternative for each of the following HVAC systems. Compare the energy end-uses and indoor temperatures in all the rooms in January and July:
(i) Base case but with Fan Coil system. Make sure to keep the same lighting/equipment/occupancy densities as the base case.
(ii) Same as (i) but all the rooms are air-conditioned with a Variable Air Volume (VAV) System.
2-
Analysis Requirements:
For each run, summarize the annual energy end-uses (For VisualDOE, you can use View Results reports; For DOE-2.1E, you can use the BEPU reports) and monthly average indoor temperatures (using the Diagnostics report in VisualDOE) in the unit. Discuss the validity of your findings and summarize your results and discussion in a brief report to be handed at the end of the lab session.
Summary of Results:
|
| ||||||||||||||||||||||||||||
|
Discussion of
Results
Justify and comment on the results summarized above for
each of the measure. Briefly indicate if the results do (or do not) make sense
to you and why. Use the back of this sheet if you need more
space.
If
you have troubles getting the results, indicate the specific reasons and problem
areas.
Appendix
C
This
appendix includes the list of tasks that the trainees had to perform for the
site-visit of the EPT buildings as part of the their
group project requirements.
Walk-Through Assignment
EPT Buildings
Data
to be collected:
During the walk-through, try to obtain the
following information in order to model the three sections of the EPT building
(residential apartments, administrative building, and the classrooms) using
VisualDOE:
· General information about the hotel including number of floors and the conditioned area of each floor. Try to sketch a layout of each floor.
· Basic construction details of walls. In particular, determine if there is thermal insulation in the wall.
· Type of glazing (single pane or double pane) for the windows and typical dimensions of the windows.
· Lighting and equipment survey for a typical floor.
· Type of the HVAC system. In particular, determine the size of the chillers and possibly through testing an estimate of their efficiency.
·
General
protocol for operating and controlling the HVAC systems.
· Utility billing data for at least one year (it is recommended to obtain data for three years).
Most of the
information listed above should be obtained during the tour. However, if you are missing any details, try to
obtain it just of the tour by asking Prof. Krarti.
Modeling Using VisualDOE
Using the information collected above, model
the EPT building as it currently is operated. In
particular, your base-case model should predict close monthly electricity use
when compared to the utility bills (electricity bills). Once, you developed a calibrated model of the
hotel, determine the energy and cost savings from appropriate energy efficiency
measures. Examples of energy efficiency measures that could be suitable for EPT
include:
· Convert the existing system to VAV system.
·
Use a more
energy-efficient chiller (kW/ton of 0.60 for rotary compressors).
·
Install
daylighting sensors in all the guest
rooms.
·
Replace
all the incandescent lamps by CFL lamps (typical CFL lamp consumes 18 W and has
an efficacy of 45 lumens per watt).
You should perform the computer modeling and
present your findings as part of the final group project due on