FACULTY OF ENGINEERING AND SUSTAINABLE DEVELOPMENT
Department of Building, Energy and Environmental Engineering
Energy mapping of public buildings
A case study at Älvkarlebyhus
Kieran Crowley
2016
Student thesis, Master degree (one year), 15 HE Energy Systems
Master Programme in Energy Engineering, Energy Online Course
Supervisor: Roland Forsberg,
Examiner: Taghi Karimipanah
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Preface
I would like to thank my company supervisor H
åkan Karlsson for providing information and support during my time at Älvkarlebyhus. I would also like to thank the staff of Älvkarlebyhus for making me feel welcome and relaxed at the office. I would also like to thank to my
supervisor from the college Roland Forsberg with his guidance and support I would have not been able to complete this thesis and I also like to extend a thanks to all the staff at HIG involved in the energy online masters as it’s been a very pleasant experience studying on line.
Final I would like to thank my family and friends who supported and encouraged me throughout
my studies.
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Abstract
The aim of this report is to identify all energy systems in the Skutskärs Vårdcentral and Folktandvården building, Centralgatan 12 building and the Library building to be studied in this report and carry out an investigation on whether the energy systems efficiency may be increased by improving on the elements or factors that affect the energy systems.
A model of the buildings energy systems were created in Microsoft excels using the steady state method and modifying it to calculate an average heating session. Average monthly temperatures calculated over a thirty year period were used to calculate heat loss due to transmittance, infiltration and ventilation. Internal heat gains and losses were included in this model. Where calculation for heat gains or losses was to complex or the required data was not available rule of thumb was used.
Once results were gained it was seen that the greatest area of loss of heat was from the building structure by transmittance of heat through the materials. An investigation was carried out to reduce the heat loss due to transmittance. Both solution involved adding insulation to the wall and top ceiling in both solution the insulation level was varied to show how much energy could be saved by varying the thickness of insulation. It was found in both solution that the energy saving ranged from 9% to 13%. Go to section 4.6 for details in improvements. Unfortunately quotes for material and labour for each method could not be obtained and without quotes a recommendation to which to invest in cannot be given. The Älvkarlebyhus management should use the areas of the external wall and ceiling area provided in appendix A to obtain quotes from respected companies in Sweden. The areas in appendix A should be double checked before looking for quotes to ensure accuracy in obtaining quotes. This was tried by the author but failed for the following reasons:
Companies would not respond to e-mails
Also when searching for Swedish companies online there web site was in Swedish and no
English option to read the material on the site was available. Meaning the author could not gain the required information needed to calculate cost.
The third solution involved lowering the internal temperature of the building. When the internal temperature was lowered to 17°C and 15°C reduction in energy usage by 10.95% and 16.82%
was seen respectively.
No other area where improvements could be carried out for the following reasons:
The heat pump combined with the district heating and the use of heat recovery devices
makes the energy system providing heat for hot water and the heating system highly efficient. There are no improvement worth the financial cost and the interruption to the occupants of the buildings.
On Visual inspection the equipment was maintained to a high standard avoiding the need
to create a maintenance schedule.
Insulation on pipes and ducts coming and going from plant rooms to the building were to
a high standard. No repairs or improves are needed.
The lighting system is an area where energy can be reduced to justify the cost of
installing more energy efficient lights and better controls. An experienced person should
investigate this as it requires specify knowledge and experience to select the suitable
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lighting system to reduce cost. Implementing lights with the wrong controls system can cause poor lighting levels in the building and health problems such as headaches for the occupants. It may also increase the energy consumption of the building if the wrong lighting fixtures and controls were selected.
A cheap and easily technique to implement would to advice the occupants of the building to turn off equipment and lights when are not needed. Hanging signs by exits of room as a reminder.
This seems obvious but as the author carried out a visual inspection of the buildings concerned in this report it was noted that lights were left on in areas no one was to be seen. The same was seen for equipment such as computers.
The insulation levels for the walls and ceiling should be increased to improve heat loss due to transmittance. Improving insulation would also decrease the heat loss due to infiltration. There is no reliable way of calculating the percentage of reduction as using the results from a pressure test is the only reliable way of calculating heat loss from infiltration once the improvements have been carried out. Also to compare before and after the improvements a pressure test would have to be done before any improvements are carried out to make an accurate comparison.
The buildings in this report relies heavily on electricity for providing lighting, heating and ventilation. For this reasons it is recommended that a feasibility study be carried whether PV solar panels or wind turbines could produce electricity for the buildings studied in this report.
The advantages and disadvantages of PV panels and wind turbines are covered in the conclusion section of this report.
Älvkarlebyhus can be proud that the building in this thesis releases no CO
2or other harmful greenhouse gases as the greenhouses gases released from the production of the district heating system and electricity suppliers are taken into account by the suppliers of these energy sources.
Making them an environmentally friendly building.
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Table of Contents
1. Introduction ... 5
2. Theory ... 7
2.1 Energy mapping ... 7
2.2 Steady state conditions ... 7
2.3 Internal gains ... 8
2.4 Infiltration gains ... 8
2.5 Solar gains ... 9
2.6 Thermal transmittance losses ... 10
2.7 Ventilation ... 11
2.8 Heat recovery ... 13
2.9 Passive design ... 13
2.10 Creating or using a model ... 14
2.11 Controls of the system ... 14
2.12 Reference data ... 16
3. Method ... 17
4. Process and results ... 29
4.1 Skutskärs Vårdcentral, Folktandvården building ... 29
4.2 Library ... 34
4.3 Centralgatan 12 building ... 36
4.4 Energy balance for all three building. ... 38
4.5 Visual inspection ... 39
4.6 Improvements ... 41
Solution 1 ... 41
Solution 2 ... 42
Solution 3 ... 43
Solution 4 ... 43
5. Discussion ... 45
6. Conclusions ... 49
7. References ... 51
8. Appendices ... 53
8.1 Appendix A: Areas to be used for quotes. ... 53
8.2 Appendix B: Flow chart ... 54
8.3 Appendix C: Inputs and calculations for Skutskärs Vårdcentral, Folktandvården building. ... 55
8.4 Appendix D: Inputs and calculations for Library building. ... 74
8.5 Appendix E: Inputs and calculations Centralgatan 12 building. ... 90
8.6 Appendix F: Heating input by heating system. ... 108
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1. Introduction
Due to global warming becoming more of an international issue. Energy usage in modern society is a concern for all governments and citizens. This is why governments are now setting new building standards to reduce the energy usage and to cut down on greenhouse gases emissions of it’s nation by using more energy from renewable source’s, better control systems to ensure the systems are not operating when not needed, upgrading current building and energy systems structures and more efficient equipment. Governments also agree to international or EU policy and directives to reduce energy consumption and greenhouse gasses emissions by a certain percentage. Building standards are set to make these targets possible such agreements are made legally bidding and penalties may occur by any country that failed to meet its agreed target. An example of such a policy is the Energy efficiency policy in Europe where EU member country that agreed to the policy has to achieve the following targets by the year 2020:
Increase energy systems efficiency by 20%.
Reduce greenhouse gasses by 20%
Increase energy from a renewable source by 20%
The figures above may differ from country to country depending on the renewable resources available to utilize and the current economy situation of the country.
The push from governments for more energy efficient building and an energy system with the lowest impact on the environment has companies concerned about their corporate image. One way of improving corporate image is to invest in low energy systems with low level of greenhouse gas emissions for any buildings belonging to the company. This is achieved a number ways and there’s no one solution for all building as key factors that affect the energy systems for buildings will change from building to building. Energy mapping helps to identify the building energy systems and creates an energy balance of the gains and loss of the factors that affect the energy systems. This can help to identify key areas where the energy usage could be improved on and to reduce CO
2emissions according to a English study “The energy use
within buildings for heating and lighting, etc, accounts for more than 40% of the CO2 released to the atmosphere in the UK”1. It can also help to keep track of the energy system performance over a period of time. A sudden fall in performance may indicate part of the systems is experiencing a fault or has stopped operating completely and slow decline may indicate poor maintenance issues.
The aim of this report is to use energy mapping to reduce the energy consumption for the Skutskärs Vårdcentral, Folktandvården building and Centralgatan 12 building and the Library building managed by Älvkarlebyhus with the hope of better thermal comfort and to see a decrease in energy usage in each building. It is important to gather all information required for the thesis form reliable sources as incorrect information can have serious impact on the results and conclusion of the report. The information required for this project came from engineering documents to assist in ensuring the proper steps were taking when calculations and when making key decisions that have a major effect on the outcome of the project. The supervisor also gave some documents that were required to perform calculations others were gained by the author’s time in college. Älvkarlebyhus supplied information about the building and its energy system as they were required too.
1 Ref GPG 303 The designer’s guide to energy-efficient buildings, page 6
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2. Theory
To explain the theory involved in this paper each topic will be given a sub heading of its own and a description given of what it is and how it affects the work done in this paper.
2.1 Energy mapping
Having a good methodology process in place is critical for the success of any project. This is where energy mapping comes into play. It sets out a plan of action for the person carrying out the work and if followed the greater the chance for success. The first step in this process is identifying all energy suppliers for example Electricity and the district heating suppliers. The second step is to identify which system will use the energy been supplied. The third step is to create a flow chart to give a visual aid to represent of the overall energy system of the building.
With the help of the flow chart the factors that affect each sub energy systems can be identified for example the following factors affect the heating system:
1. Design room temperature.
2. U-values of the building envelope.
3. The internal gains from people, equipment, lighting system and solar gains.
4. Air tightness of the building.
5. Ventilation requirements.
6. Outside temperature.
2.2 Steady state conditions
The steady state method calculates the energy loss and input in an energy system for one moment in time. This method is used when sizing equipment for the buildings energy systems for example the size of the pipes for the hot water distribution system and heat emitters for the heating system. The method can be modified to calculate the energy balance of a building over a period of time by one main technique described below:
1. If a weather data file is available the time steps in which the temperature was measured on a daily basis can be used as steady state condition to calculate the energy balance at that point. It’s important for each steady state condition to be multiplied by the length of time between time steps in order to account for the time missing between measurements to produce more accurate results. Care must be taken when using this process as the results may not represent typical heating session. If a weather data file is used during a time were the weather condition behaved to an extreme manner the results will be over or under estimated. This can be avoided by averaging weather conditions over a period of time. 30 years is the preferred length of time among engineers. But if the data for that length of time is not available or too expensive to purchases a shorter period is acceptable.
The above method will be used but with two changes the first change, no data files where
available so average temperature for a month will be used. The average temperature for each
month was calculated over a period of 30 years which makes it a reliable and accurate. The
second change, Since average temperature for the month is used only one steady state condition
will be calculated then converted into kW*h by dividing the results by 1000 to convert into kW
and then by the operational hours of the equipment to gain kW*h. Once this is achieved the
energy balance can be create and the investigation on how to improve the system can begin.
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2.3 Internal gains
Internal gains are the heat gains in a building that come the following:
People give off heat when carry out an activity. The amount of heat released depends on
the level of activity the person is doing for a seated person it is said that they release 115W (ASHRAE Handbook 2005)
2of heat compared to when someone is working out in a gym they give out 585W (ASHRAE Handbook 2005)
2of heat. The comparison above shows how important it’s to select the right activity when including heat gains from people as the wrong choice could have a serious impact on the results in fact the above example shows if the wrong activity is picked the calculation will be off by a factor of 5.1. Another important factor to get right is the amount of people within the space concerned. As the heat gain from people will be multiplied by all people within the space will be included in the calculation.
Equipment within the building can contribute to internal heat gains mainly in office and
industry building. For domestic homes they usually not considered as they usually have a small or no impact on the heating load. Heat gains from equipment can be found in engineering documents and on the equipment manuals. Equipment such as computers and data storage device or any device for keeping food cold should be included.
Lighting system in a building converts all electricity into heat. Heat gains from lights can
be found in engineering documents given in the form of watts per square meter. There is a lot of potential in reducing the energy demand of a building from the lighting system by installing more efficient lights and better controls.
2.4 Infiltration gains
All building materials allow a certain amount of outside air to pass through it into the building.
Air also enters the building through gaps or cracks in the external structure of the building.
Where doors and window are fixed to the external wall air may pass through more easily around gaps in frames of the doors and windows as they may have not be sealed correctly. The amount of air passing through the frame and seals depends on the ability of the crafts man fitting the doors and window. The infiltration through these gaps or cracks will differ from building to building. This is mostly wind driven process but other factors may contribute to this such as air pressure and difference in external and internal temperatures. Depending on wind direction and wind velocity different parts of the building will experience different infiltration gains. This is difficult to calculate or create a model to account for this. The only accurate way to gain accurate results for infiltration rates is to do a pressure test. A pressure test on a building involves closing all vents, opening in the external wall, external doors and external windows. Once this is done one of the external doors is removed and an air tight device containing a fan is attached to where the door was. The fan is than turn on blowing air into the building until the pressure in the building reaches 50Pa. Once the pressure reaches 50Pa the fan shuts down and the time it takes for the building to reach atmospheric pressure is used to calculate the infiltration rate of the building. See figure 1 overleaf for an image of the equipment used.
2 Nonresidential cooling and heating load calculations ASHRAE Handbook: Fundamentals (ch. 30) (Atlanta GA:
American Society of Heating, Refrigerating and Air-conditioning Engineers) (2005)
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Figure 1 Air pressure test equipment. Source: Google images 3
2.5 Solar gains
Solar gains come into the building in two forms.
Indirect this is where the solar gains that are reflected by an object and then entered the
building through a window.
Direct is where the solar gains enter the building from it source.
Solar gain are hugely impact by the size of the window according to one English study “Wall
glazing should not normally exceed 10% of the total external wall area for the optimise the solar gains ”4Solar gains can help to reduce the energy demand on the heating system but care must be taking to prevent solar gain during summer months from overheating the building. A Compromise between maximizing for solar gain during heating season and minimizing solar gains during the cooling seasons must be made. Not all solar energy enters the building through the window some is reflected or absorb by the window as seen figure 2 below:
Figure 2 Solar gains through the window. Source: Google images.5
3 Google images, Air pressure test equipment.
4 GPG 304 The designer’s guide to energy-efficient buildings , page 20.
5 Google images, Solar gains through the window.
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The amount solar energy reflected, transmitted and absorb by the glass will depend on the properties of the glass which can be altered during the production stage of the glass to gain the desired amount of solar energy been reflected, transmitted and absorb by the glass. This will impact the designer choice of windows selected for any building project.
2.6 Thermal transmittance losses
Heat flows from the inside of the building through the buildings structures to the external environment when the internal temperature is greater than the external temperature. As seen in figure 3 below:
Figure 3 Heat loss due to heat transmittance through the building envelope. Source: Google images.6
Each element of the building structure will have a number of layers each with its own propose.
The number of layers and type will depend on a number of issues such as:
Which structure is being considered?
The design criteria of the structures has to meet.
The local weather climate.
Client’s opinion on how the external and internal surfaces should look like.
Whether the client wants a low or zero energy buildings or a building meeting current
building standards.
Thermal resistance of the materials used in the construction of the structure.
The width of the structure that the heat passes through.
The thermal resistance in each layer will add to the overall thermal resistance of the structure.
The amount of heat loss due to thermal transmittance losses will depend on the factor listed above. The temperatures difference between the internal and external is one of the main factors that affect thermal transmittance losses the larger the difference the greater the thermal transmittance loss.
6 Google images, heat loss in a building.
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U-values are important factor when design a building as they will affect the size of heating and cooling equipment. Also as U-values increase the infiltration rate is usually lowered as a result.
Designers must be careful as there is a point to where the cost of improvement to the thermal resistance of a structure will outweigh the saving of energy. The point where you save the most energy at the least cost is referred to as the cost optimal. U-values are calculate using the method of how much resistance electrical resistors provide when in series or parallel in an electrical circuit. This method of calculating is explained in more detail in section 3 step 4.
2.7 Ventilation
This is the process of suppling fresh air into a building in order to remove containments, odours and moisture. Ventilation rates for building can be found in engineering documents and will differ depending on the type of building being considered. Poor ventilation rates may cause the people occupying the building to experience poor thermal comfort and illness. Leading to complaints to management about work conditions being poor. This can cause serious problems for the designer and energy firms as it decrease profits on the project also could give the frim a bad reputation if the problem not resolved in a proper and professional manner. There are two types of ventilation:
1. Passive ventilation is where the ventilation is supplied by natural means without any mechanically equipment. One example of such a system is opening in the walls such as vents to allow air to enter the building and exist through an opening opposite the vent that the air enters form. This process is wind driven or caused by the convection movement of air due to difference in temperature between the internal temperatures and external temperature of a building. An example of such a design can be seen in figure 4 overleaf which uses the above factors to provide ventilation for a building. There are number of solution to choice for passive ventilation but it is not important to go into greater details as the basic technique is only needed in this project. The limitation of natural ventilation is “In areas where openings are only on one wall, wind pressure ventilation will be
limited to a room depth of around 6 m. With openings on opposite walls, cross- ventilation occurs and can be effective in areas up to 12 m wide. Similarly, stack effect ventilation can be effective for horizontal distances up to 12 m between the wall opening and roof opening. Most effective natural ventilation will be achieved by using a combination of low-level openings (eg windows) and some at high level (eg roof vents)”77
GPG 303 The designer’s guide to energy-efficient buildings , page 76
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Figure 4 Example of passive ventilation. Source: Google images8
2. Mechanical ventilation is the use of mechanical equipment to supply or extract air needed to maintain air quality to a predetermine level. It can be achieved by supply air into a room causing a positive pressure or extract air from the room causing a negative pressure in the room. The difference between positive and negative pressure in a room is the negative pressure allows air form the adjoining rooms and external environment to enter much more freely. In a positive pressure room the air is likely to enter an area with lower pressure. Depending on the need of the room one of the above would be pick to best suit the ventilation requirements of the room. An example of supply and extract system can be seen in the figure 5 below:
+
Figure 5 Example of mechanical ventilation. Source: Google images.9
8 Google images, passive ventilation.
9 Google images, mechanical ventilation.
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Poor ventilation can have the following side effect on the building:
The removal of commitments not been effectively removed could cause sick building
syndrome. Where there a high number of people occupying the building getting sick but there no one cause for it and can’t be easily fixed. Building related illness may occur as well but in this case there in one main factor causing the illness and a lot easier to fix.
Bad odour in the building
A build-up of moisture causing the growth of harmful bacteria and dangerous organisms
in the building.
2.8 Heat recovery
For building to be efficient it’s essential to recapture waste heat and utilize it again to lower the energy demand on the energy systems. A heat recovery device is used to capture the waste heat.
The thermal wheel used here to explain how such a device operates. A thermal wheel is located in the AHU of the building. The extract duct is located above the supply duct and as the thermal wheel rotates it transfers heat from the extract duct to the supply duct. Exhaust air from rooms with high contaminates may not be usable to pass through the thermal wheel as there’s a risk of cross contamination. Exhaust air form toilets would be a good example of this. See figure 6 for a diagram of how a thermal wheel operates. Each heat recover deceive operates in a similarly manner but the method of recovery of the heat will differ.
Figure 6 Thermal wheel. Source: Google images.10
2.9 Passive design
Once the energy mapping and energy balance have been created it’s important to impalement passive techniques were possible. Passive designs aim’s to take advantage of the natural rescores available at the location of the building to reduce the energy requirements and the impacted of the building energy systems has on the environment. It also uses orientation of the building to lower the demand on the energy systems.
The following are examples of how the cool, heating load and the electricity needed for the lighting system can be reduced:
Prevent solar gains enter the build by using plants that grow in the summer high enough
to prevent gains through windows and then cut them for winter to allow gains through the window.
Using light wells to increase the amount of natural light entering the building.
10 Google images, Thermal wheel.
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Allowing solar gains in during the heating period to decease the heat load on the heating
system.
Actuators are hydraulic mechanical devices that open windows to allow the correct
amount of air to enter the room for ventilation proposes.
Passive design is difficult to implement on building that have been built. As the orientation, building elements and window size is already decided. But what can be done is change the internal layout of the building to maximize on the passive design technique.
2.10 Creating or using a model
When creating a model and carrying out simulations on the model it’s important to know the difference of the two. A model is the mathematical representation of a physical energy system and a simulation is using the parameters such as outside temperature, u-values and indoor air temperature to name a few and entering the information into the model to gain results such as energy demand for the year, size of heat emitter’s .Modelling can also be used to compare different technologies to help the designer’s to choice the best energy system. There are a number of modelling tools available to engineers today for example IDA ICE, modest and reMIND. Care must be taking when using any modelling software packages as the limitations must be known to the user to avoid problems with clients and projects. Simple models are often more desired as complex model have higher risk of error and the cost tends be increase as the complexity of the model increases. The amount of information needed to be inputted into the model also increases with complexity.
2.11 Controls of the system
Controls are used to maintain some conditions of a process or internal environment of a building within acceptable levels which a designer would state. There are three basic control concepts:
1. There’s a set point which must be maintained for building one such condition would be temperature. This is known as the controlled variable.
2. The second would be the variables that need to change in order to maintain the set point.
Changing the flow of hot water to a heat emitter is a good example of this. This is known as the manipulated variable.
3. The factors that cause the controlled variable to vary from the set point are referred to as disturbances. A chance in outdoor temperature is an example of this.
The most common type of controls used in industry is the PID controls. They are easy and cheap to implement. Controls can be modelled and simulations to identify the best combination before put to use. This increase the probability of the controls system performing to their best of their ability. The PID controls is as follows:
Proportional (P): The error is detected by the sensor and the proportional control will
reply by trying to correct for the size of the error at that moment in time.
Integral (I): The errors are added over a period of time and the integral control acts
accordingly.
Derivative (D): The rate of change in the error is calculated and the derivative control
acts accordingly.
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The P and I control can act aggressively and cause an overshoot of the set point. This may mean that it will take the system longer to reach the set point or not at all. When this occurs the system osculates and unlikely to reach the set point.
There are two types of control systems that are used:
1. Feedback control: This is where a sensor measures the output from a process than sends a signal to an error detector which measures the difference between the output measurement and the set point. The error is then send to the feedback controller which varies the manipulate variables to return the output back to the set point. Feedback control is always negative to ensure the controlled variable returns to the set point. If a positive feedback was used the difference in the set point and controlled variable would increase. See figure 7 overleaf:
Figure 7 Feedback control. Source: Google images.11
2. Feedforward control: the disturbances in the system are measured before they affect the controlled variable. The manipulate variable are than changed to keep the controlled variable at the set point see figure 8 below:
Figure 8 Feedforward control. Source: Google Images12
The difference between the two are in the feedback control it’s correct an error that’s been made where as in the feedforward it prevents an error from occurring.
11 Google images, feedback control.
12 Google images, feedforward control.
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2.12 Reference data
This is where data for a given period of time such as outside temperature for the duration of a heating session is used in a model in order to calculate energy usage of a building. Typically weather seasons based on the location of the building are reliable and accurate to gain results.
However since averages temperatures over a thirty year period are available and more accurate to
calculate energy usage a reference temperature year will not be used. But the amount of
Saturday, Sunday and bank holiday in 2016-2015 heating period will be used as reference data.
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3. Method
In order to gain results for this thesis a excel tool was created to produce results and visual aids in explaining the outcomes of the simulations. Most of the information gathered for the data input section will be needed in several calculations throughout the process. This makes excel a more efficient way of gaining results. The steps taken to create the excel tool are listed below along with the required information need to complete this paper.
1. Collect information on the energy system.
2. A list of data inputs Sheet had to be created. This would contain Information such as indoor temperature, outdoor temperature for the different months etc as seen in figure 9 below. The image does not show all inputs but shows the basic layout of the input spreadsheet. Also the months of September and may will be divided by 2 in all calculations.
Figure 9 Screen shot of data inputs
3. The next step was to create the building envelope by using cad drawing to find the areas of the walls, floor, ceiling, roofs, windows and doors.
4. If the u-values been given just enter the values in the required cells in the excel tool. If no u-values or information given to calculate u values then standard u values for Swedish buildings will be used as seen in table 1 below.
Table 1 Table of u-values13.
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European insulation manufactures association.
Room temperature (°C) 21
second level Month Number of days Number of hours per month Operation time (hrsper month) Average temperature Wall 0.18
Sep 30 720 113 10.7 Door 3
Oct 31 744 188 5.3 window 2
Nov 30 720 181 0.9 Ceiling 0.13
Dec 31 744 198 -2.1 Floor 0.15
Jan 31 744 180 -5.1
Feb 28 672 181 -4.9
Mar 31 744 198 -2.2
Apr 30 720 180 3.3
May 31 744 86 8.7
Solar gains Windows
oreniation Sep Oct Nov Dec Jan Feb Mar Apr May
N 900 470 200 80 130 340 730 1350 2350
NE 2200 1010 270 90 160 400 1720 3320 4460
NW 2200 1010 270 90 160 400 1720 3320 4460
E 3520 2110 840 350 550 1550 3050 4220 5130
W 3520 2110 840 350 550 1550 3050 4220 5130
SE 4820 3570 1910 1060 1440 2900 4520 5420 5840
S 6130 5620 3480 2030 2710 4880 6320 6390 5710
SW 4820 3570 1910 1060 1440 2900 4520 5420 5840
Correction factor 0.58 0.51 0.42 0.43 0.45 0.49 0.58 0.58 0.63
Outdoor temperature (°C) U-Value (W/M2/K-1)
Wall 0.18
Door 3
window 2
Ceiling 0.13
Floor 0.15
U-Value (W/M2/K-1)
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Windows u-values were given by the supervisor and the rest at EURIMA web-site.
But if the information to calculate the following formulas should be used to calculate u- values:
To calculate u-values for layers in series use formula 1 to 4
14below:
F1
𝑈 = 1
𝑅
𝑠𝑖+ 𝑥1 𝑘1 + 𝑥2
𝑘2 + 𝑥3 𝑘3 + 𝑅
𝑠𝑒𝑈 = 𝑈 𝑣𝑎𝑙𝑢𝑒 (𝑊/𝑚
2𝐾)
𝑅
𝑠𝑖= 𝐼𝑛𝑡𝑒𝑟𝑛𝑎𝑙 𝑠𝑢𝑟𝑓𝑎𝑐𝑒 𝑅𝑒𝑠𝑖𝑠𝑡𝑎𝑛𝑐𝑒𝑠 𝑜𝑓 𝑎𝑖𝑟 (𝑚
2𝐾/𝑊) 𝑥 = 𝑡ℎ𝑖𝑐𝑘𝑛𝑒𝑠𝑠 𝑜𝑓 𝑚𝑎𝑡𝑒𝑟𝑖𝑎𝑙 (𝑚)
𝑘 = 𝑡ℎ𝑒𝑟𝑚𝑎𝑙 𝑐𝑜𝑛𝑑𝑢𝑐𝑡𝑖𝑣𝑖𝑡𝑦 𝑜𝑓 𝑚𝑎𝑡𝑒𝑟𝑖𝑎𝑙 (𝑊/𝑚𝐾) 𝑅
𝑠𝑒= 𝐸𝑥𝑡𝑒𝑟𝑛𝑎𝑙 𝑠𝑢𝑟𝑓𝑎𝑐𝑒 𝑅𝑒𝑠𝑖𝑠𝑡𝑎𝑛𝑐𝑒𝑠 𝑜𝑓 𝑎𝑖𝑟 (𝑚
2𝐾/𝑊) For structure with two or more layers in parallel use the following formula below:
F2
𝑅
𝑇= 𝑅
𝑈+ 𝑅
𝐿2
𝑅
𝑇= 𝑅𝑒𝑠𝑖𝑠𝑡𝑎𝑛𝑐𝑒 𝑡𝑜𝑡𝑎𝑙 (𝑚
2𝐾/𝑊) 𝑅
𝑈= 𝑅𝑒𝑠𝑖𝑠𝑡𝑎𝑛𝑐𝑒 𝑢𝑝𝑝𝑒𝑟 (𝑚
2𝐾/𝑊)
𝑅
𝐿= 𝑅𝑒𝑠𝑖𝑠𝑡𝑎𝑛𝑐𝑒 𝑙𝑜𝑤𝑒𝑟 (𝑚
2𝐾/𝑊)
Before the total resistance can calculated the upper and lower resistance must be calculated by the following formulas (F3 and F4):
F3
𝑅
𝑙= 𝑅
𝑠𝑜+ 𝑅
𝑛+ 𝑅
𝑛+ 1 𝑃
𝑛𝑃
𝑛+ 𝑃
𝑛𝑃
𝑛+ 𝑅
𝑛+ 𝑅
𝑠𝑖𝑅
𝑢= 1
𝑃
𝑛𝑅
𝑠𝑜+ 𝑅
𝑛+ 𝑅
𝑛+ 𝑅
𝑛+ 𝑅
𝑠𝑖+ 𝑃
𝑛𝑅
𝑠𝑜+ 𝑅
𝑛+ 𝑅
𝑛+ 𝑅
𝑛+ 𝑅
𝑠𝑖F4
𝑅
𝐿= 𝑅𝑒𝑠𝑖𝑠𝑡𝑎𝑛𝑐𝑒 𝑙𝑜𝑤𝑒𝑟 (𝑚
2𝐾/𝑊)
𝑅
𝑠𝑖= 𝐼𝑛𝑡𝑒𝑟𝑛𝑎𝑙 𝑠𝑢𝑟𝑓𝑎𝑐𝑒 𝑅𝑒𝑠𝑖𝑠𝑡𝑎𝑛𝑐𝑒𝑠 𝑜𝑓 𝑎𝑖𝑟 (𝑚
2𝐾/𝑊) 𝑅
𝑛= 𝑅𝑒𝑠𝑖𝑠𝑡𝑎𝑛𝑐𝑒 𝑜𝑓 𝑚𝑒𝑡𝑒𝑟𝑖𝑎𝑙 (𝑚
2𝐾/𝑊)
𝑃
𝑛= 𝐴𝑟𝑒𝑎𝑠 𝑜𝑓 𝑚𝑒𝑡𝑒𝑟𝑖𝑎𝑙 𝑖𝑛 𝑝𝑎𝑟𝑒𝑙𝑙𝑒𝑙 (𝑚
2)
14 A guide to HVAC Building Services Calculations BSRIA Guide 30-2007,chp 3, page 21
19
𝑅
𝑠𝑒= 𝐸𝑥𝑡𝑒𝑟𝑛𝑎𝑙 𝑠𝑢𝑟𝑓𝑎𝑐𝑒 𝑟𝑒𝑠𝑖𝑠𝑡𝑎𝑛𝑐𝑒𝑠 𝑜𝑓 𝑎𝑖𝑟 (𝑚
2𝐾/𝑊)
Once the u-values are obtained the next step is to calculate the heat loss through the building structures by using formula 5
15below and the table 2 for average temperatures for Gävle below was used since no data for average temperatures could be found for Skutskär where the building are located and Gävle being the nearest location with the data required. U-value (W/K/m
2)
F5
Q = A ∗ U ∗ ∆T Q = Heat loss (W)
A = Area ( 𝑚
2) U = U-value (W/K/m
2)
∆T = Difference in temperature (°C)
Table 2 Monthly average temperatures (°C)16
When the above and below calculations are completed the results will have to be converted into kWh by dividing by 1000 than multiply by the operation hours of the equipment and in case of the number of heat gains from people multiply by the opening hours of the building.
Using the areas measured in step 2 for windows and information given by the supervisor for solar gains and both correction factors as seen in tables 3 to 5 over leaf calculate the solar gains using formula 6
17below:
F6
𝑄
𝑆𝑂𝐿= 𝐴 ∗ 𝑆 ∗ 𝐶
𝑆∗ 𝐶
𝐴𝑄
𝑠𝑜𝑙= 𝑆𝑜𝑙𝑎𝑟 ℎ𝑒𝑎𝑡 𝑔𝑎𝑖𝑛 (𝑊ℎ𝑚
2𝑑𝑎𝑦) A= Window area (𝑚
2)
S= Solar gain W/𝑚
2day C
s= Correction factor for shading C
A= Correction factor for absorption
15 CIBSE guide B: The Chartered Institution of Building Services Engineers Guide B, Heating, ventilating, air conditioning and refrigeration chp1, pg 15, equ 1.3.
16 Klimatdata för Sverige, Statens institute för Byggnadslorskning.
17 Dwelling Energy Assessment Procedure manual, chp6, page 31.
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Gävle 5 -5.1 -4.9 -2.2 3.3 8.7 13.8 16.6 15.3 10.7 5.3 0.9 -2.1
Average temperature (˚C) for a year
Location Monthly Average temperature (˚C)
20
Table 3 𝑺𝒐𝒍𝒂𝒓 𝒉𝒆𝒂𝒕 𝒈𝒂𝒊𝒏 (𝑾𝒉/𝒎𝟐/𝒅𝒂𝒚)18
Table 4 Calculation factors for windows according to cloudy days18
Table 5 Calculation factors for windows according to sun radiation18
Once the above result is calculated it is than multiplied by the number of day in that month.
18 Information given by the supervisor.
Latitude 60˚N
Month -180 -150 -120 -90 -60 -30 0 30 60 90 120 150
0 130 130 160 550 1440 2360 2710 2360 1440 550 160 130
10 70 70 70 90 140 180 200 180 140 90 70 70
0 370 370 640 1550 2900 4280 4880 4280 2900 1550 640 370
10 340 340 400 1030 2240 3530 4020 4530 2240 1030 400 340
0 730 900 1720 3050 4520 5740 6320 5740 4520 3050 1720 900
10 710 730 1290 2460 3920 5290 5970 5290 3920 2460 1290 730
0 1350 1990 3320 4750 5850 6370 6410 6370 5850 4760 3320 1990
10 1170 1640 2810 4220 5420 6160 6390 6160 5420 4220 2810 1640
0 2350 3050 4460 5630 6150 5980 5730 5980 6150 5630 4460 3050
10 1840 2570 3910 5130 5840 5920 5710 5920 5840 5130 3910 2570
0 3210 3870 5320 6190 6350 5820 5460 5820 6350 6190 5230 3870
10 2420 3180 4570 5650 6070 5790 5430 5790 6070 5650 4570 3180
0 2830 3510 4910 5960 6280 5820 5580 5890 6280 5960 4910 3510
10 2270 3020 4410 5540 6050 5870 5560 5870 6050 5540 4410 3020
0 1700 2380 3720 5020 5850 6070 5970 6070 5850 5020 3720 2380
10 1400 2020 3240 4550 5520 5950 5940 5950 5520 4550 3240 2020
0 900 1230 2200 3520 4820 5760 6130 5760 4820 3520 2200 1230
10 880 1070 1930 3200 4530 5580 6080 5580 4530 3200 1930 1070
0 510 530 1010 2110 3570 4960 5620 4960 3570 2110 1010 530
10 470 480 650 1500 2850 4290 4870 4290 2850 1500 650 480
0 200 200 270 840 1910 3040 3480 3040 1910 840 270 200
10 160 160 160 300 990 1590 1810 1590 990 300 160 160
0 80 80 90 350 1060 1770 2030 1770 1060 350 90 60
10 40 40 50 60 90 120 130 120 90 60 50 40
N E S N
Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
Month Calculation factor
Jan 0.45
Feb 0.49
Mar 0.58
Apr 0.58
May 0.63
Jun 0.61
Jul 0.61
Aug 0.59
Sep 0.58
Oct 0.51
Nov 0.42
Dec 0.43
Window type U-value Calculation factor
1-glass, normally 5.4 0.9
2-glass, normally 2.9-3.0 0.8
3-glass, normally 1.9-2.0 0.72
Special glass 1.0-1.5 0.69
2-glass, energy glass 1.0-1.5 0.7
21
1. The internal gains from people, equipment and the lighting system have to be accounted for. This was achieved by creating a spread sheet using tables below and over leaf that give energy given off by people, equipment and the lighting systems were used at this point in the calculation process. The day was broken down into one hours period’s. Than two columns were create one for each of the gains below. One for the amount energy been released and the other for the number of people or equipment. In the case of the lighting system this differed slightly one column was for the energy released per meter squared and the other for the area of the building. A survey of the building had to be carried out to identify the equipment in each building using the table 6 below.
Table 6 Sheet to be used for inspection of building to record equipment in the building.
The data collect is then entered into the excel tool and using the IF function in excel if the time period was greater than zero than the following calculation were to be completed.
Total
Total
Total
Total
Fluorescent triphoshor Select lighting type
Other equipment:
Desktop
Lighting type Compact
fluorescent Metal halide
Small Desktop
Desktop size Count the equipment using the space below
Copier size Count the equipment using the space below
Desktop
Office Small office
Large office Small desktop
Desktop 16-18 inch
Printer size Count the equipment using the space below
Count the equipment using the space below 13-15 inch
Date of inspection
Monitors size
Equipment in building Name of building
Address of building Inspector of building
22
For equipment and people use formula 719
below:
F7
𝑄 = 𝑞𝑒 ∗ 𝑛 𝑄 = 𝐻𝑒𝑎𝑡 𝑔𝑎𝑖𝑛 (𝑊)
𝑞𝑒 = 𝐻𝑒𝑎𝑡 𝑟𝑒𝑙𝑒𝑎𝑠𝑒𝑑 𝑏𝑦 𝑒𝑞𝑢𝑖𝑝𝑚𝑒𝑛𝑡 𝑜𝑟 𝑝𝑒𝑜𝑝𝑙𝑒 (𝑊) 𝑛 = 𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑝𝑒𝑜𝑙𝑝𝑒 𝑜𝑟 𝑒𝑞𝑢𝑖𝑝𝑚𝑒𝑛𝑡
Values for heat released by equipment and people carrying out different activities can be found in the tables 7 to 12 below and overleaf.
Table 7 Values for heat given off for different PC sizes . Source: 20Wilkins C K and Hosni M (2000)
Table 8 Values for heat given off for different monitors sizes . Source: 20Wilkins C K and Hosni M (2000)
Table 9 Values for heat given off for different copiers sizes. Source: 20Wilkins C K and Hosni M (2000)
Table 10 Values for heat given off for different printers sizes . Source: 20Wilkins C K and Hosni M (2000)
19 Course notes from CIT: Building Thermal Dynamic Analysis, Fergus Delaney.
20 Wilkins C K and Hosni M H 2000: Wilkins C K and Hosni M H Heat gain from office equipment ASHRAE J. 42 (6) 33 (June 2000).
Nature of value FOR PCS
Total rate of heat emission (W)
Average 55
Conservative 65
Highly conservative 75
Monitor size
Total reate of heat emission (W)
Small (13-15 inch) 55
Medium (16-18 inch) 70
Large (19-20 inch) 80
Copier size Heat Emissions (W)
Desktop copier 20
Office Copier 300
Printer Size Heat Emissions (W)
Small Desktop 10
Desktop 35
Small office 70
Large office 125
23
Table 11 Values of heat released by people doing different activities. Source 21 ASHRAE Handbook 2000
For lighting use the formula (F8)22
:
(F8) 𝑄 = 𝑞𝑙 ∗ 𝐴 𝑄 = 𝐻𝑒𝑎𝑡 𝑔𝑎𝑖𝑛 (𝑊)
𝑞𝑙 = 𝐻𝑒𝑎𝑡 𝑟𝑒𝑙𝑒𝑎𝑠𝑒𝑑 𝑏𝑦 𝑙𝑖𝑔ℎ𝑡𝑠 (𝑊/𝑚
2) 𝐴 = 𝐴𝑟𝑒𝑎 (𝑚
2)
Heat gains from different lighting equipment can be found in table 12 below.
Table 12 Values given for different lamp types and lux levels. Source: Code for Lighting 200423
21 Nonresidential cooling and heating load calculations ASHRAE Handbook: Fundamentals (ch. 30) (Atlanta GA:
American Society of Heating, Refrigerating and Air-conditioning Engineers) (2005)
22 Course notes from CIT: Building Thermal Dynamic Analysis, Fergus Delaney.
23 Code for Lighting (London: Society of Light and Lighting)-2004
Degree of acticity
Total rate of heat emission for adult male (W)
Steated at theated 115
Steated,very light work 130
Moderate office work 140
Standing , light work :walking 160
Sedentary work: Restaurant 145
Light bench work: Factory 235
Moderate dancing 265
Walking: light machine work:Factory 295
Bowling 440
Heavy work: Factory 440
Heavy machine work: Factory: lifting 470
Athletics 585
24
2. The energy loss due to infiltration is calculated using the following steps and formulas F9 to F11
24below.
Step 1: Calculate surface area of the internal structures and volume of the building using
these formulas.
F9
𝑆 = (2 ∗ (𝑊 + 𝐿) ∗ 𝐻) + (𝐿 ∗ 𝑊) 𝑆 = 𝑆𝑢𝑟𝑓𝑎𝑐𝑒 𝑎𝑟𝑒𝑎 (𝑚
2)
𝑊 = 𝑊𝑖𝑑ℎ𝑡 (𝑚) 𝐿 = 𝐿𝑒𝑛𝑔ℎ𝑡 (𝑚) 𝐻 = 𝐻𝑖𝑒𝑔ℎ𝑡 (𝑚)
𝑉 = 𝐿 ∗ 𝑊 ∗ 𝐻 𝑉 = 𝑉𝑜𝑙𝑢𝑚𝑒 (𝑚
3)
𝐿, 𝑊 𝑎𝑛𝑑 𝐻 𝑎𝑟𝑒 𝑡ℎ𝑒 𝑠𝑎𝑚𝑒 𝑎𝑠 𝑎𝑏𝑜𝑣𝑒
Step 2 is using the information form the step 1 to calculate the air infiltration rate for the
building using the formula (F10) below:
F10
𝐼 = 1 20 ∗ 𝑆
𝑉 ∗ 𝑄
50𝐼 = 𝐼𝑛𝑓𝑖𝑙𝑡𝑟𝑎𝑡𝑖𝑜𝑛 𝑟𝑎𝑡𝑒 (𝐴𝐶𝐻 𝑆
−1)
𝑆 = 𝑆𝑢𝑟𝑓𝑎𝑐𝑒 𝑎𝑟𝑒𝑎 (𝑚
2) 𝑉 = 𝑉𝑜𝑙𝑢𝑚𝑒 (𝑚
3) 𝑄
50𝑆 = 𝐴𝑖𝑟 𝑙𝑒𝑎𝑘𝑎𝑔𝑒 𝑖𝑛𝑑𝑒𝑥 ( 𝑚
3ℎ )
Step 3 Use the results from the previous steps to calculate the heat loss from infiltration
by using the formula below:
F(11) 𝑄
𝑖𝑛= 1
3 ∗ 𝐼 ∗ 𝑉 ∗ ∆𝑇
𝑄
𝑖𝑛= 𝐻𝑒𝑎𝑡 𝑙𝑜𝑠𝑠 𝑑𝑢𝑒 𝑡𝑜 𝑖𝑛𝑓𝑖𝑙𝑡𝑟𝑎𝑡𝑖𝑜𝑛 (𝑊) 𝐼 = 𝐼𝑛𝑓𝑖𝑙𝑡𝑟𝑎𝑡𝑖𝑜𝑛 𝑟𝑎𝑡𝑒 (𝐴𝐶𝐻
−1)
∆𝑇 = 𝐷𝑖𝑓𝑓𝑒𝑟𝑛𝑐𝑒 𝑖𝑛 𝑡𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒 (°C) 𝑉 = 𝑉𝑜𝑙𝑢𝑚𝑒 (𝑚
3)
3. Heat loss from ventilation. The air flow in the AHU must be measured using an multi- function anemometers. The below image shows an matrix of measurements in a AHU.
Four holes are drilled into the side of the duct equally spaced apart and at each hole four measurements are taking to from a matrix of measurements as seen in the figure 10 overleaf.
24 CIBSE TM 23 2000 : The Chartered Institution of Building Services Engineers TM 23 testing building for air leakage 2000,ISBN 1903287103
25
Figure 10: Matrix of measurements in the AHU. Source: google images.25
The purpose of this is to gain accurate results as the air flow through the duct differs across the area of the duct. The results are than averaged and the results are then used in formula 12
26below to calculate the heat loss due to ventilation can be calculated.
F12
𝐻𝑣 = (1 − 𝛽
100 ) ∗ 𝐶𝑝 ∗ 𝜌 ∗ 𝑄𝑣 ∗ (𝑇𝑖 − 𝑇𝑜) Hv = Heat loss from ventilation (W)
Cp= Specific heat capacity (J/kg K) ρ= Mass density (kg/m
3) Qv = volumetric flow rate (m
3/s)
Ti= Temperature inside (°C) To= Temperature outside (°C) β= Hear recovery efficiency (%)
4. Gather bills for cold water for one heating session. Form the bills calculate the total amount of cold water used in the building of interest than using this figure estimate the hot water usage for non-heating proposes by using the following formula 13
27:
F13 𝑄
𝐻𝑊= 1
3 ∗ 𝑞 ∗ 1.16 ∗ ∆𝑇
𝑄
𝐻𝑊= 𝐴𝑚𝑜𝑢𝑛𝑡 𝑜𝑓 ℎ𝑜𝑡 𝑤𝑎𝑡𝑒𝑟 (𝑘𝑊ℎ)
𝑞 = 𝑀𝑎𝑠𝑠 𝑓𝑙𝑜𝑤 𝑟𝑎𝑡𝑒 𝑜𝑓 𝑐𝑜𝑙𝑑 𝑤𝑎𝑡𝑒𝑟 𝑢𝑠𝑒𝑑( 𝑚
3ℎ𝑒𝑎𝑡𝑖𝑛𝑔 𝑠𝑒𝑠𝑠𝑖𝑜𝑛 )
∆𝑡 = 𝐷𝑖𝑓𝑓𝑒𝑟𝑒𝑛𝑐𝑒 𝑖𝑛 𝑡𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒 (°C)
5. Adjust excel tool to exclude Saturdays, Sunday and bank holidays by using the heating session of 2015-2016 as a reference.
6. Once the excel tool is created the data must be enter into the model once all relevant data is enter the model will produce the results. All calculations are the same for each building.
25 Google images, Matrix of measurements in the AHU
26 www.engineeringtoolbox.com. heat loss.
27 Formula giving by supervisor.
26
7. Create an energy balance using the results from the previous steps.
8. Using the energy balance investigate areas where improvements can be carried out to improve on energy usage of all three building.
9. Carry out a visual inspection to determine whether improvements can be made in the following areas:
Insulation on pipes and ducts.
Fix holes, gaps and cracks on the envelope of the building.
If maintenance can be improved on the equipment.
The following is a list of engineering documents and software package used to complete this paper:
1. Microsoft word and excel
2. Documents given by the supervisor Roland Forsberg.
3. The Chartered Institution of Building Services Engineers Guide A- Environmental design (CISBE Guide A- Environmental design)
4. The Chartered Institution of Building Services Engineers Guide F- Energy efficiency in buildings (CIBSE Guide F- efficiency in buildings)
The following instruments were used:
1. Multi-function anemometers: To measure air velocity in side duct.
2. Digital capture hood: to measure air velocity from supply or extract diffuser.
3. Architectural scale rulers to measure lengths and heights of wall, windows and door on cad drawings.
The following word key words or phrases were used to search for information using google:
Energy mapping.
Infiltration heat losses.
Ventilation heat losses.
Air exchange rates for buildings.
Wind speed and direction for Gävle.
Insulation suppliers in Sweden.
Energy benchmarks for building in Sweden.
