Gordon Library Energy Efficiency...will offset the libraries electricity usage. Installing...

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Gordon Library Energy Efficiency

A Great Problem Seminar Project Proposal: Submitted to

Worcester Polytechnic Institute

By:

Jian Mao

[email protected]

Ryan Mocadlo

[email protected]

Ryan Shooshan

[email protected]

Lauren Waring

[email protected]

December 16, 2009

Faculty Advisor:

Brian Savilonis

mailto:[email protected]




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Abstract

We preformed cost calculations on different methods to make Gordon Library at WPI more energy efficient. We focused mainly on the insulation of windows and walls, the analysis of different methods to decrease the amount of energy used by computers and televisions, and the feasibility of installing a photovoltaic system on the roof. The windows and walls both proved to have viable payback options while the photovoltaic system proved to have long run cost benefits. The Technology in the Library, if switched from logged-out mode to standby mode can save the Library money in the short run if awareness is raised.

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Acknowledgements:

We really appreciate the following individuals’ invaluable aid. They answered our questions, keep us focused and gave us suggestions on our project.

Bryan A. Ferguson

Bruce M. Fiene

William G. Grudzinski

Tracey Leger-Hornby

Yvette M. Rutledge

Brian Savilonis

Erik Silva

David Spanagel

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Table of Contents

Title Page…………………………………………………………………………………………1 Abstract……….………………………………………………………………………………….2 Acknowledgements…………………………………………………………………………3 Table of Contents…………………………………………………………………………....4 Background……………………………………………………………………………………..5 Goals……………………………………………………………………………………………….6 Executive Summary…………………………………………………………………………7 Literature Review: Photovoltaics…………………………………………………………………………..9 Windows………………………………………………………………………………..10 Walls………………………………………………………………………………………13 Technology……………………………………………………………………………..14 Methodology: Photovoltaics………………………………………………………………………….16 Windows………………………………………………………………………………..16 Walls………………………………………………………………………………………16 Technology…………………………………………………………………………….17 Analysis/ Results: Photovoltaics………………………………………………………………………….18 Windows………………………………………………………………………………...20 Walls……………………………………………………………………………………….24 Technology……………………………………………………………………………..26 Conclusion: Photovoltaics………………………………………………………………………….33 Windows………………………………………………………………………………..33 Walls………………………………………………………………………………………33 Technology……………………………………………………………………………..34 Bibliography…………………………………………………………………………………….35

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Background: Gordon Library located on WPI’s campus was built in 1967. Since the library is 42 years old and the only renovation done was for more offices, the original structure has remained unchanged. The original windows and the walls are poor insulators and a consistent draft of wind can be felt from the panes and the walls which are made of cement. Therefore this creates a good amount of heat and energy loss. The library provides numerous computers for use by WPI students. Having such a large amount of computers can cause a major draw of energy from the library. Cutting down on the energy draw from the computers will offset the libraries electricity usage. Installing Photovoltaics (PV) also known as solar energy may help to offset the overall electricity draw as well as save the library money. With the help of insulation, photovoltaics, window treatments, and cost analysis’s, the library can potentially reduce heat, electricity and energy loss.

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Goals:

Increase efficiency of Gordon Library by adding insulation to walls and windows

Find amount of energy and money saved by using different modes of computers and televisions

Determine whether or not photovoltaics will be viable for the Library

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Executive Summary: Gordon library, which was built in 1967 was not created for maximum energy efficiency. The 42 year old building bears great energy loss every year which costs the Library and Worcester Polytechnic Institute thousands of dollars each year. Narrowing down on the energy inefficiency within Gordon Library, the main incentive of this group’s project brought the group to major conclusions and recommendations representing the energy situation within the library. Through careful research, observations, and calculations the project objective was met with data, analyses, and payback prices. The four main aspects of the Library that were acknowledged were: the installment of photovoltaic’s onto the roof, the installment of thermal window shades, the installment of added wall insulation, and the analysis of the technology in the Library. For the photovoltaic system, the area of the roof of the library is permitting to a 62.4 kilowatt photovoltaic system. The estimated total cost of the system is approximately $305,000. Although this is a large initial cost, the Library would be saving about $17,000 yearly from the investment. Without added inflation the photovoltaic system will have a payback time of about 19 years. Yearly heat loss through the windows is costing the Library approximately $14,000. With added insulation the heat loss in the library will greatly reduce. With duette semi opaque window shades the money lost due to heat loss will be about $11,000 less than the windows without the shades. For triple honeycomb windows the money lost due to heat loss will be about $12,000 less than the windows without shades. Unlike the photovoltaic system the window shades have a much shorter payback price three to four years for the duette semi opaque window shades and three and one half to four and one half for the triple honeycomb shades. Yearly heat loss through the walls is measured very similarly to the window heat loss. The Library is losing approximately $34,000 each year to the loss of heat through the cement walls. The addition of insulation to the walls is the best way to reduce the heat loss. With the addition of Tuff R insulation the heat loss was reduced to approximately $5,000 a year. Since the insulation has a large initial cost approximately $52,000 the payback period for the walls came out to be about three years. For the technology portion, a general analysis was done to observe how much money is used in the different modes of the computers and televisions in the Library. The different modes that were investigated were when the computers and television are in normal use (for computers logged out screen), in maximum use (only for computers), in standby, and turned off. The analysis that was done showed that the most money is lost through the maximum usage of the computer while when the computer is logged out, or in standby mode the power usage is greatly reduced. This is also true for the televisions, when the televisions are turned off or in standby mode the energy consumption and dollars consumed is much less than if the television were in normal use.

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The Library can cut their energy consumption immediately by adding photovoltaics, installing insulation, and reducing technological energy consumption. But is immediate action the best move for the Library? With large insulation costs immediate action may not be in the best interest of the Library. For photovoltaics, the calculated results led us to believe that the long term benefits of the installation of photovoltaics would be best. The system has a payback period of about 19 years and since photovoltaic systems last for about 25 to 30 years the long run benefits and money saved after the payback period would make the photovoltaics viable. The Payback period for the thermal windows shades of three and four years is a viable short and long run investment. Not only will the investments pay for the initial costs in less than five years, but the investment will continue to save WPI money in heating and cooling costs long after the project is complete. However, Insulating the walls would be a very obtrusive project, if the project is done over the summer, it could be a viable option for reducing energy loss from the library. Reducing the timing of standby mode of the computers in the library would also help to reduce energy consumption. In addition, light work such as word processing and checking E-mails will also help to save energy in the short and long run. If these projects are completed the Libraries energy consumption will be reduced ultimately saving the Library money.

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Literature Review:

Photovoltaic

Adding a photovoltaic system to the library helps greatly shift how WPI provides power

for the library. What the photovoltaic system will do is shift how the energy is produced cutting

down on the need to buy energy from the grid. Many colleges have already begun to take

advantage of adding photovoltaic systems to their buildings. Harvard has installed 192 panels on

the roof of one of the buildings on campus, which produced around 36kW of solar energy. What

the photovoltaic system has done, other than cut down on energy bills, is reduce the schools

carbon dioxide emissions. Harvard has stated that their system has reduced their carbon dioxide

production by about 75,000 pounds per year, which is equivalent to the annual emissions of 220

cars(Walsh, 1). The total for Harvard’s photovoltaic system came to around 365,000 dollars.

They did not have to pay all the money though because of a grant from the Massachusetts

Technology Collaborative, which is a state agency for the development of renewable energy.

From the grant they got 143,500 dollars and the rest of installation cost was paid by

Harvard(Walsh, 2). With the grant from Massachusetts Technology Collaborative about 40% of

the total installation cost for Harvard. What the grant did for Harvard is reduce the payback

period of their photovoltaic system. The Massachusetts Technology Collaborative is a fairly new

group. The governor of Massachusetts, Governor Patrick, has given $68 million to the

Massachusetts Technology Collaborative to support the installation of 250 MW of solar systems

in Massachusetts(Giudice,1). The way the Massachusetts Technology Collaborative decided how

much funding a certain program gets is by the size of the photovoltaic system. If the system is

from 1 to 25kW then the owner gets $2.00 per watt. If the system is over 25kW but under 100kW

then the owner gets $2.00 per watt for the first 25kW and $1.70 for the remaining photovoltaic

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system. For systems over 100kW but under 200kW then the owner gets the price of $2.00 for the

first 25kW, $1.70 for the second 75kW and $1.00 for the remaining kilowatts(Commonwealth,

19).

For our project we needed a way to calculate the maximum energy output for a certain

photovoltaic system. The site that we used was one created by the department of energy and it

was called PV Watts. What PV Watts does is allow the user to put in different specs of a

photovoltaic system. The user is able to put in the tilt of the system, the size of the system, the

location and the current cost of electricity. After all of that information is put it calculates how

much energy one can expect from that specific system and also the amount of money one can

save(PVWatts, 1). The information calculated can then be used to calculate the payback period

and then decided whether or not the system could be a viable source of energy.

Windows

The windows in WPI have not been changed or renovated in the life span of the structure.

The Library has approximately 104 single paned windows. Singled paned windows can transfer

over 84 percent of infrared energy from a sealed room to the outside. (NFRC- The facts about

windows and heat loss) Window treatment can significantly reduce heat loss and add to the

efficiency of the whole structure. A main method for window treatment which is attractive,

effective and cost efficient is the implementation of thermal window shades. Windows shades

have been proven by International building performance simulation association (Ibpsa), as well

as proposed by Building Systems for Interior Designers to reduce energy consumption of a

structure.( Binggeli, 183; Laouadi,1697) Ibpsa concluded that older structures can improve their

energy efficiency with a little initial cost by installing shades. Ispsa’s numerous studies showed

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that in temperate zones the hourly heat loss was reduced from 114.88 watts/hour to 99.28

watts/hour (13.58% reduction), and that in cold zones the heat loss was reduced from 123.53

watts/hour to 108.95 watts per hour (11.80% reduction). ( Laouadi)

Window shades can prevent up to eighty percent heat loss in the winter as well as up to

eighty-six percent heat gain in the summer. (Binggeli, 190) Heat removal can be measured by a

U-value which represents how well a product prevents heat escape. The U-value, which is the

inverse of the R- value for other structural applications, is primarily used for window

calculations. As the U-value decreases the better an insulator the product is. The value usually

falls between .20 and 1.20 for windows varying on the type of window. (Binggeli, 188; NFRC -

The NFRC Label; SeriousWindows) Calculating the U-value depends on the amount of heat

transfer (Q), the area of the window (A), the indoor temperature (Tt), and the outside temperature

(Ta). Where U= Q/ A(Tt - Ta ). For the Library the A value will stay consistent depending upon

the location of the window while the Temperature (T) values will fluctuate depending upon the

season. The Q value can be determined by the heating power of the heater in watts (E), the

transfer of heat through walls (NLC), the indoor temperature (Tt) and the outside temperature

(Ta). Where Q = E- NLC(Tt - Ta ). The difference of the U of the windows for the existing

structure and the U value of the structure with curtains will show the inefficiency of the

preexisting structure, and how much heat is actually lost. (Fang, 550-52) While the U-value can

be derived from the heat loss, the area of the windows, and the inside and outside temperatures;

heat loss can be derived from a known U value. A ¼ inch thick singled paned window has a U-

value of approximately 1.01, and a ½ inch thick singled paned window has a U-value of

approximately .97. (Glass U-Value Performance) Along with a known U value, degree days can

be used for an average region temperature. (Home Heating Energy) There are both heating and

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cooling degree days; heating degree days are counted by the summation of degrees less than 65

degrees Fahrenheit and cooling degree days are counted when the temperature is over 65 degrees

Fahrenheit. Over the past two years (2007-2008) the average heating degree days for the both

years is 7909 degree days while the average cooling degree days is 750 degree days. (Heating &

Cooling Degree Days) Since the Library is run off of natural gas to heat the building, and

electricity to cool the building two different final conversions would be needed to estimate the

cost of heat loss for heating and cooling degree days. For a cost analysis of heating degree days

a conversion using cubic feet and British Thermal Units (BTU) (100 ft.3 = 100,000 BTU) would

be multiplied to another conversion evolving the cost in cubic feet of fuel ($15.5/1000 ft.3).

(Energy Information Administration) While for cooling degree days a conversion using Kilowatt

hours (Kwh) and BTUs (2.39 x 10-4

Kwh = 1BTU) would be multiplied by cost of electricity per

Kwh ($0.1817= Kwh). (Energy Information Administration) With this information the Total

cost of heat loss can be accounted for in the Library.

Due to the great numbers of windows in the library, the use of manual curtains would

prove difficult to operate day in and day out. Motorized window shading systems are offered,

and have multiple options and styles. Remotes, timers, wall switches, and operating systems are

all systems that can be installed for window shade systems. (Boston Shade Company)

Automatic window shades are also beneficial because the weather in the North East typically

fluctuates from season to season which creates variances in temperatures. In Worcester the

average temperature in January is twenty-four degrees while in July the average is seventy

degrees Fahrenheit. (Massachusetts Weather) The fluctuations from month to month varies the

heating and cooling of buildings from week to week. Window shades can provide better

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insulation for the windows which would reduce heat loss thus making a less stressful workload

for the heating and cooling systems in the library.

The honeycomb window shade, unlike other cloth window shades is designed for

insulation and energy efficiency. The window shade has multiple honeycomb shaped

compartments that are designed to trap air and act as an insulator. (Boston Shade Company)

There are multiple variations of honeycomb shaped shades, the shades offer different R values

and designs to decrease heat loss efficiency. The duette 3/8 semi- opaque classic has an R-value

of 3.5 while the duette triple honeycomb has an R-value of 4.8. With an added R-value to the

window heat loss, and therefore cost will decrease.

Walls

The U.S. Department of Energy suggests that if places such as attics, ducts spaces,

exterior walls, and foundations are properly insulated, this can boost a building’s energy

efficiency.( Energy) There are also non energy benefits that result from adding insulation to a

building. With added insulation, there is less of a draft that comes in from the outside and the

walls are less susceptible to moisture damage. (Non-Energy) Insulation improves fire safety; the

cellulose in insulation materials makes walls up to 75 percent more fire resistant. (Product)

Insulation is not only a way to increase a buildings energy efficiency level but a way to make

areas more comfortable by keeping them warm. (Non-Energy)

There are multiple types of insulation that you can use for different applications. A few

types are, loose fill insulation, spray/liquid foam, and blanket (batt and roll). Loose-fill insulation

is made up of small fiber or foam particles. It has the ability to conform to spaces without

affecting the structure. The fibers can consist of cellulose, fiberglass, or rock/slag wool, which

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are produced using up to 75% recycled materials. The R value is about 3 per inch; an R value is

used as a measure to determine how much a material will resist heat transfer. A higher R value

results in a greater insulating effect and lower heat transfer. One downfall to this type of

insulation is that settling often occurs which reduces the R value. However if it is installed at the

proper density then no significant settling should occur. It is more likely to occur in cases of

“fluffing” when a lower density than needed is added which may be caused by a poor contracting

job; fiberglass is more “fluffable”. Liquid foam is also available, which, can be sprayed, injected,

or poured into available space. This can fill more volume, and has twice the r value. Available

types are cementitios, phenolic, polyisocyanurate, and polyurethane; other types of foam can be

used but they tend to be less common, and some are harmful to the consumer. Foam is usually

more expensive than traditional insulation. Traditional blanket insulation, comes in batts or rolls,

and most commonly is made from fiberglass. It is suited to fit the area between wall studs and

can be trimmed to fit. Standard blankets have an r value between 2.9 and 3.8 per inch this can

range from 3.7 to 4.3. (Energy) Another insulation option is foam board, or insulation paneling.

This may be more convenient in cases where the building is pre-existing, and a case you are

working with concrete walls such as basements. (Products) One type of foam board that could

be used is Tuff-R. It has a high R value of 12.

Technology Besides heating and cooling in the library, computers consume the majority of the

electricity. It is a large waste of electricity when electronics are not used.

Generally, a typical desktop computer uses approximately 65 to 250 watts per

hour.(Saving Electricity) A Computer operating for a whole day with 100 Watts/hour uses

876kWh a year. If the computer uses 250 Watts, the power consumption will rise to 2190 kWh

per year. (Martin)

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There are a few factors that affect the consumption of electricity of computers, these

factors include computer operating modes, types of computers and processors, the use of

computers, and the use of the Internet. When a computer sleeps or is in standby1 the monitor

energy consumption is less than 6 Watts, which is approximately 5% of electricity consumption

of an active computer. (Energy Savers) When the computers are in the logged off mode they are

still active even though there is not a program running. A laptop can consume a range of 15 – 60

Watts per hour, so a way to save energy is by raising awareness of the use of laptops. Both slow

and new processors, use the same amount of energy when doing tasks such as e-mails and word

processing. (Minimize Your Computer’s Energy Use) When computers are turned-off computers

continue to consume electricity. This mainly occurs at night when the computers are shut off.

1 To some degree, sleep mode is the same as the standby mode .

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Methodology:

Photovoltaic

Determine what size photovoltaic system can be installed on the roof of the library by

looking at blue prints. Calculate the yearly kilowatt hours that can be produced by such a system

and how much money can be saved yearly. Find the price of the system by looking at average

installation price of $6.70(Cost,1). Determine the amount of money that can be received from the

MTC grant. Finally calculate the payback period of the system with inflation prices of electricity.

Windows Determine window shade types, prices, and U or R-Values for the window shades.

Estimate an installation for the window shades. Find an automation system and price for the

windows that would be able to run on a self timing system. Investigate the blue prints of the

library to determine the windows dimensions and the number of windows in the Library.

Calculate the heat loss of the library without window shades. Calculate the heat loss of the

library with the added U-value from the window shades. Calculate a payback period for the

initial cost of the window shades

Walls

In order to look into insulating the walls of the library it is important to learn about the

different types of insulation available and what could be best used in the environment given;

along with the amount of heating and cooling degree days in Massachusetts. With this

information the heat lost can be calculated. Which from there the amount of money lost can be

calculated. Then this number along with the total materials cost can be used to find a rough

payback period.

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Technology

First, we collect general information about computers and televisions in the library. In

order to do this, we first asked the chief engineer, Mr. William G Grudzinski. He was able to

show us a blue print how electricity is distributed on campus. Next we contacted with Bruce M.

Fiene, the video systems specialist in ATC (Academic Technology Center). He provided us

detailed information about the amount and models of computers and televisions in the library.

We used this information to then determine the consumption of energy used in different modes

of the computers and televisions.

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Calculations:

Photovoltaic

We began the calculations for the photovoltaic system by calculating the area of the

library roof. How we calculated the area was by looking at the blue prints of the roof. By looking

at these blue prints we were able to calculate the area to be approximately 15600ft2. Using

15600ft2 as the area we were able to find that it would be possible to install a 62.4kW system.

How we came up with a 62.4kW system was by using average size and production of other

photovoltaic systems. We found that we would need about 20% of the total area in order to

achieve maximum sun light, which left 12480ft2 of available space. Using the average

production of a photovoltaic system as 5W we found that 62400W could be produced or

62.4kW(Ramon, 6). What we did next was plug the size of the photovoltaic system and a few

other variables into an online calculator. What PVWatts did was take all of these variables into

account and then calculates the yearly kWh produced and the amount of energy saved per year.

PVWatts calculated the yearly kWh to be approximately 90100kWh/yr and a savings of about

$17,000/yr. The next step in the calculations was to find out what the total cost of the system

would be. Using the average price of a photovoltaic system, which came to $6.70 per watt, we

found that the total cost of the system would come to $418,000(Cost,1). $418,000 is the price of

the system without the grant from the Massachusetts Technology Collaborative, which was

calculated using the table from the methodology. From the table we can see that our system can

only receive the first two rebates because our size is only 62.4kW. How our system's grant is

calculated is by taking the first 25kW of the system and multiplying that by $2.00 per watt. Once

that amount is known it is then added to 37.4kW multiplied by $1.70 per watt, which is the

amount of money given for energy production between 25kW and 100kW. When calculated we

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found the total of the grant to be $114,000 giving a new total of $305,000 for the system. The last

step in the calculations was to find how long the payback period of the system would be. For this

calculation we made a graph that showed payback periods with different inflations in the price of

electricity shown below:

What we can see from the graph is that if the price of electricity rises then the amount of money

saved from the energy produced by the system increases. So if the price of electricity was to stay

constant then the payback period would come to approximately 18 years but if the price of

electricity increased by 15% per year then the payback period would be cut to approximately 9

years.

$0.00

$50,000.00

$100,000.00

$150,000.00

$200,000.00

$250,000.00

$300,000.00

$350,000.00

$400,000.00

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

Tota

l Mo

ne

y Sa

ved

Payback Time Adjusted for Inflation

0%

5%

10%

15%

Cost of System

Year

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Windows

To calculate heat loss of the library windows and an estimated window pane thickness of

a ¼ an inch was used to determine the U-value of the singled paned windows. Since the

variables for heat loss calculation (Q) were unavailable in the equations U= Q/ A(Tt - Ta ), and

then in Q = E- NLC(Tt - Ta ) the idea of calculating heat loss with an estimated U-value became

the solution. After determining the U-value of the windows, and the heating and cooling degree

days of the Worcester, the calculation of square inches of the windows was calculated by looking

at the blue prints of the Library. With this information along with the two conversions for the

heating degree days equations: cubic feet per British Thermal Units (BTU) (100 ft.3 = 100,000

BTU) and cost in cubic feet of fuel ($15.5/1000 ft.3), the cost of heat loss for temperatures less

than 65 days can be determined for the Library. Since the libraries cooling system is run by

electricity and not natural gas like the heating system the cooling degree days are calculated by

kilowatt hours instead of natural gas where 2.39 x 10-4

Kwh= 1BTU and $0.1817= 1Kwh. The

following two equations determine the heat loss for both heating degree days and cooling degree

days respectively:

A. Heating- 7909 degree days

𝑄 = Degree Days hours

day U − value (area of windows)

cubic ft .

BTU $ Natural Gas

cubic ft

𝑄 =

7909 24 hours

day 1.01

BTU

h degree F (sq .ft .) (530,280.75 sq. in)

sq .ft .

144sq in

1 cubic ft .

1000 BTU $15.5 Natural Gas

1,000 cubic ft

=$10,942.75 ≈ $11,000

B. Cooling- 750 degree days


day U − value (area of windows)

Kwh

BTU $ Electricty

Kwh

𝑄 =

750 24 hours

day 1.01

BTU


sq .ft .

144sq .in .

0.000239 Kwh

BTU $0.1817 Electricty

Kwh

= $2,907.30 ≈$3,000

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Total heat loss:

A+B= $14, 000

The heating and cooling degree day equation costs are then both added together to reach the total

cost of heat loss per year (as seen above). Using both the duette 3/8 semi- opaque classic which

has an R-value of 3.5 and the duette triple honeycomb which has an R-value of 4.8 the heat loss

of the windows with shades can be determined by adding the R-value of the window (1/1.01) and

the R-value of the shade together. After the summation, the U-value can be determined by taking

1/ R(window) + R(shade). The new U-value is then plugged into equation A and B. to get the

heat loss cost with the shade.


1. Duette semi opaque window shade R=3.5

𝑅 𝑤𝑖𝑛𝑑𝑜𝑤 = 1

1.01 + 3.5 = 4.490 𝑈 𝑤𝑖𝑛𝑑𝑜𝑤 =

1

4.490= .2227

𝑄 =

7909 24 hours

day . 2227

BTU


sq .ft .

144sq in

1 cubic ft .


1,000 cubic ft

=$2,412.17 ≈ $2,500

2. Duette Triple Honeycomb window shade R= 4.8


1.01 + 4.8 = 5.7901 𝑈 𝑤𝑖𝑛𝑑𝑜𝑤 =

1

5.7901= .1727

𝑄 =

7909 24 hours

day . 1727

BTU


sq .ft .

144sq in

1 cubic ft .


1,000 cubic ft

=$1867.86≈ $2,000


1. Duette semi opaque window shade R=3.5


1.01 + 3.5 = 4.490 𝑈 𝑤𝑖𝑛𝑑𝑜𝑤 =

1

4.490= .2227

22

𝑄 =

750 24 hours

day . 2227

BTU


sq .ft .

144sq .in .

0.000239 Kwh


Kwh

= $64.10 ≈ $100

2. Duette Triple Honeycomb window shade R= 4.8


1.01 + 4.8 = 5.7901 𝑈 𝑤𝑖𝑛𝑑𝑜𝑤 =

1

5.7901= .1727

𝑄 =

7909 24 hours

day . 1727

BTU


sq .ft .

144sq in

0.000239 Kwh

BTU $0.1817 Electr icty

Kwh

=$49.71≈ $50.00

The heating and cooling degree day equations costs are then both added together to reach the

total cost of heat loss per year of each shade.

-Total heat loss duette semi opaque window shade :

Q= A1+B1≈ 2,600

-Total heat loss duette Triple Honeycomb window shade:

Q= A2+B2≈ 2,100

Below is a graph of the of heat loss of the windows with and without the shades

$0

$2,000

$4,000

$6,000

$8,000

$10,000

$12,000

$14,000

$16,000

Duette Semi Opaque Shades U= .2857

Duette Tripple Honeycomb Shades

U= .2083

Library Windows U=1.01

Heat Loss ($)

Heat Loss ($)

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The website that sells the duette window shades had a calculator to estimate the total cost of the

duette semi opaque window shades and the duette triple honeycomb windows shades. Since

there are three different types of windows in the library the calculation was run three times for

the duette semi opaque windows shades and three times for the duette triple honeycomb

windows shades. The calculator required the demensions of each of the windows which are 39 1

2

in. x 100 in. for the small windows, 23 in. x 117 in. for the medium windows, and 45 9

16 in. x 117

in for the larger windows. After each calculation was complete the total number of windows in

the library: 6 small, 6 medium, and 92 large were multiplied by the cost respectively. The total

cost of the duette semi opaque window shades are approximately $32,500 ($32,175.20) without

installation costs, and the duette triple honeycomb window shades are approximately $41,500

($41, 197.28) without installation costs. To account for the installation cost of the windows an

estimated cost was used. The estimated cost totaled to $3,200 =

4 workers 20 dollars

hour

8 hours

day 5days. This totaled the duette semi opaque window shades to

approximately $35,500, and the duette triple honeycomb window shades to about $44,500. An

estimated cost of an automation system for the windows was difficult to determine because the

online company that sells the duette shades did not directly offer an automation system with the

windows, and the Boston Shade Company said that the price of the automation system would

have to be determined later. Therefore the price of an automation system would have to be

regarded later, most likely at the time of installation.

To calculate the payback price, the equation is set up so that the heat loss with the curtains would

be subtracted from the initial heat. This number would then be divided by the cost of the curtains. Where:

24

Payback = Cost of Curtians

Initial heat loss −Heat loss with Curtains

Duette semi opaque window shade payback:

$35,500

$14,000−$2,600 = 3.11≈ 3 to 4 years

Deutte triple honeycomb window shade payback:

$41,500

$14,000−$2,100 = 3. .48 ≈ 3.5 to 4.5 years

Walls

When calculating the heat loss the concrete was assumed to have a width of 18” which yielded

an R value of 1.98. Looking at past years the average heating and cooling days can be used. To

find the amount of wall space that can be insulated by taking the total space and subtracting the

window are allowing for about 17,607 square feet. Heating degree days are going to be measured

in British Thermal Units (BTU) and at a cost of natural gas at $15.5/1000ft3 (100 ft.

3 = 100,000

BTU). Cooling degree days are measured in Kwh where 2.39 x 10-4

Kwh= 1BTU and $0.1817=

1Kwh.



day 1/R (area)

cubic ft .

BTU $ Natural Gas

cubic ft

𝑄 =

7909 24 hours

day (

1

1.92)

BTU

h degree F (sq .ft .) (17607ft2)

1 cubic ft .


1,000 cubic ft=$26,980.

42 lost


25


day

1

R (area)

Kwh

BTU $ Electricty

Kwh

𝑄 = 750 24 hours

day

1

1.92

BTU

h degree F sq .ft . (17607ft2)

0.000239 Kwh


Kwh =

$7,168.19

Total heat loss :

A+B= $34,148.61

WITH INSULATION

New R 1.98(existing concrete) + 12 (Tuff-R insulation) + 0.56 (Drywall)= 14.54



day 1/R (area)

cubic ft .

BTU $ Natural Gas

cubic ft

𝑄 = 7909 24 hours

day (

1

14.54)

BTU

h degree F (sq .ft .) (17607ft2)

1 cubic ft .


1,000 cubic ft=

$3,562.75 lost



day

1

R (area)

Kwh

BTU $ Electricty

Kwh

𝑄 = 750 24 hours

day

1

14.54

BTU

h degree F sq .ft . (17607ft2)

0.000239 Kwh


Kwh

= $946.56 lost

Total heat loss (with insulation):

A+B= $4,509.31

26

For a rough estimate the approximated installation cost is about $47,000 and for materials

roughly $25,248.05($1.44 per square foot). The total cost then being $72,248.05

Payback

Payback = Total Cost

Initial loss −loss with insulation

Payback = $72,248.05

$34,148.61−$4,509.31 = 2.438 years

Technology

There are 153 computers and 7 televisions in total in the library, including 50 registered laptops and

computers in the offices and various computers labs (Media Lab, Anderson Labs A and B, Ground floor

Lab etc.).

Plasma Display (Televisions):

There are two kinds of plasma displays in the seven tech suites located in the library. The two types of

displays are NEC #P50XP10 and Panasonic #TH-50PH11UK. Calculations are shown for the energy

consumption of each type of television below:

50” NEC #P50XP10

There are four of the NEC #P50XP10 models located in the tech suites. The standard power consumption

is 370 Watts, while the consumption for the standby mode is less than 1 Watts.

(Suppose the library opens for 45 weeks per year in which every week the library is open for 106 hours

and closed for 42 hours .)

27

Total power consumption = power consumption rate(Watts)* Time (hour)* Amount

= 370 Watts * 1 hour * 4

= 1480 Watt-hours

For a year: consumption = 1480 Watt-hour*106*45= 7059600Watt-hours=7059.60kWh

Standby mode consumption=standby consumption rate(Watts)* Time (hour)* Amount

=1 Watts*1hour*4

=4 Watt-hours

For a year: consumption = 4 Watt-hours*42 *45= 7560Watt-hours=7.56kWh

50” Panasonic #TH-50PH11UK

There are also three televisions of the Panasonic#TH-50PH11UK brand. In standard mode, the Power

Consumption of each display is 455 Watts, while the consumption under standby mode is 0.1 Watts.

Assuming that all of the three displays are used in one hour.

Total power consumption= power consumption rate (Watts)* Time (hour)* Amount

= 455 Watts* 1hour*3

= 1365 Watt-hours


But in standby mode the consumption of electricity becomes much less.

Total power consumption= power consumption rate (Watts)* Time (hour)* Amount

28

= 0.1 Watts* 1 hour* 3

= 0.3 Watt-hours.

For a year: consumption = 0.3 Watt-hours*42 *45= 567Watt-hours=0.57kWh

Computers:

Dell OptiPlex GX620 and Dell 1905 FP

Except the computers in the tech suites and the laptops in the helpdest, the computers in the

library are mainly Dell Optiplex GX620 driver with Dell 1905 FP plasma monitor. There are

approximately 96 there. As for the driver, the normal power consumption is 70.51 Watts, while the

maximum power consumption is 125.25 Watts. 2 The power consumption for standby mode is 1.2

Watts. Even if the driver is turned off, it still consumes electricity at 2.3 Watts. When it comes to

monitors, the normal power consumption is 28 Watts, while the standby consumption is 2 Watts

and the turned-off mode consumes 0.7 Watts.

(1) Suppose the 96 computers are used in one hour.

①For normal condition:

This condition usually happens when students log off the computers but leave computers on.

The total electricity per hour per hour=electricity consumed by drivers + by monitors

=amount* (power rate sum *hours)

=96*(70.51+28) (Watts) *1 hour

=9656.96 Watt-hours

2 Maximum is reached when the system is running programs to maximize the power consumption while the normal/ typical

condition is that the system is performing routine task.

29

For a year: consumption = 9656.96 Watt-hours*42 *106= 42992785.92Watt-hours= 42992.79kWh

②For maximal condition:

This condition usually occurs when students is using the computers.

The total electricity per hour per hour=electricity consumed by drivers + by monitors

=amount* (power rate for driver + power rate for monitor)*hour

=96*(125.25+28)(Watts)*1 hour

=14712 Watt-hours


(2) Suppose the 96 computers are in standby mode in one hour, which is in a low power saving

mode.

The total electricity per hour =electricity consumed by drivers + by monitors


=96*(1.2+2) (Watts) *1 hour

=307.12 Watt-hours

For a year: consumption = 307.12 Watt-hours*42 *45= 580456.8Watt-hours=580.46kWh

(3) Suppose the 96 computers are in the turned-off mode in one hour, which is similar with the

case when the library is closed.

The total electricity per hour = electricity consumed by drivers + by monitors


=96*(2.3+0.7) (Watts) *1 hour

30

=288 Watt-hours


Dell OptiPlex 755 and Dell 1907 FPv (Tech Suites)

Computers in the tech suites are Dell OptiPlex 755 driver with Dell 1907 FPv monitor. Each tech suite has

a computer, so there are a total of 7 computers of this kind in the library. As for the driver, the normal

power consumption is 49.79 Watts, while the maximum power consumption is 72.61 Watts. 3 The power

consumption for standby mode is 2.59 Watts. Even if the driver is off, it still consumes electricity at 0.67

Watts. For the monitors, the normal power consumption is 67 Watts which is much higher than the Dell

1905FV mentioned before. The standby consumption is 2 Watts while the turned-off mode consumes 1

Watts.

(4) Suppose the 7 computers are used in one hour.

③For normal condition:

This condition usually happens when students log off the computers but leave computers on,

that is when the tech suites are not reserved.

The total electricity per hour=electricity consumed by drivers + by monitors


=7*(49.79+67) (Watts) *1 hour

=817.53 Watt-hours


3 Maximum is reached when the system is running programs to maximize the power consumption while the normal/ typical

condition is that the system is performing routine task.

31

④For maximal condition:

This condition usually occurs when students is using the computers in tech suites.


=amount* (power rate for driver + power rate for monitor)*hour

=7*(72.61+67)(Watts)*1 hour

=977.27 Watt-hours


(5) Suppose the 96 computers are in standby mode in one hour, which is in a low power saving

mode.



=7*(2.59+2) (Watts) *1 hour

=32.13 Watt-hours


(6) Suppose the 96 computers are in the turned-off mode in one hour, which is similar with the

case when the tech suites is closed.



=7*(0.67+1) (Watts) *1 hour

=11.69 Watt-hours


32

We can summarize above data in a table as follows,

Consumption Types

Amount Normal (Logged-off)

Maximum (Operating)

Standby (Sleep)

Turn-off

50’’NEC #P50XP10 4 7059 kWh N/A 8 kWh N/A

50’’Panasonic #TH-50PH11UK (3)

3 6511 kWh N/A 1 kWh N/A

Dell OptiPlex GX620 & Dell 1905FP (96)

96 42993 kWh 70176 kWh 580 kWh 544 kWh

Dell OptiPlex 755 & Dell 1907 FPv (7)

7 3900 kWh 4662 kWh 61 kWh 22 kWh

The average price for electricity is 18.17 cents/ kWh 4, so we can calculate the cost.

Cost Types

Amount

Normal (Logged-off)

Maximum (Operating)

Standby (Sleep)

Turn-off

50’’NEC #P50XP10 4 1283$ N/A 1.37$ N/A

50’’Panasonic #TH-50PH11UK

3

1183$ N/A 0.1$ N/A

Dell OptiPlex GX620 & Dell 1905FP

96

7812$ 12751$ 105$ 100$

Dell OptiPlex 755 & Dell 1907 FPv

7

710$ 847$ 11$ 4$

Comparing the cost of each mode, we found that Normal mode consumes much more energy than

standby mode. Suppose we change the logged-off mode into standby mode, in both of which the

computers are not used, we will much money.

4 http://www.eia.doe.gov/cneaf/electricity/epm/table5_6_b.html

http://www.eia.doe.gov/cneaf/electricity/epm/table5_6_b.html

33

Conclusion

Photovoltaic

We would recommend the installation of a photovoltaic system for the library. Our

greatest recommendation would be to wait a couple of years to install such a system though. The

reason being is that with modern day advances in photovoltaics they might be more efficient and

cheaper in the years to come. Why we believe a solar system should be installed is that it would

shift our energy consumption from a dirty, expensive fuel to a clean and free source of energy.

The shift to a clean fuel will help save money and cut down on CO2 emissions in the long term.

Windows

Installing window shades would benefit the library, and greatly reduce overall library

heatloss. With a payback period of less than five years for both the duette semi opaque window

shades and the deutte triple honeycomb window shades, the shades would easily pay for

themselves and then save the library money after the payback period is complete. The

automation system in the library would be helpful to eliminate excess work of drawing the

shades, but unfortunately the window companies were unable to estimate a quote in the allotted

project time. Luckily without an automation system the shades can still be functional and save

Gordon Library money in the long run resulting in less energy consumption.

Walls

Installing insulation at the library would be a viable option because although there is a

high initial cost there is a reasonable payback period. The installation would be a disruption to

the environment of the library however there is the possibility to do it in sections and over the

multiple breaks in the year. By doing it in sections it could; break up the initial cost into pieces.

34

Also the new look would give the library a more welcoming environment, not only benefiting the

energy efficiency of the building but in turn also giving it a new look.

Technology

Most of computers in the Gordon Library are in operating mode or logged-off mode

during the day and are turned-off at night. Computers are hardly in the sleep or standby mode

during the night. Compared to computers, televisions in the library are more energy efficient.

They are always in the standby mode which saves more electricity.

We suggest reducing the timer of standby mode of the computers in the library from ten

minutes to five minutes. This will save energy. In addition, we encourage students to change

computers into sleep mode manually when they log off. Light work such as word processing and

checking E-mails also helps save energy in the short and long run.

35

Bibliography:

Photovoltaic

· “PVWatts Solar Calculator.” The Energy Grid. N.p., n.d. Web. 3 Nov. 2009.

<http://www.pvwatts.org/>.

We were able to use this site to help find different types of solar calculators that were able to

calculate a wide range of aspects of photovoltaic systems. Not only did it have the calculators but

also tools that help one decided if a photovoltaic system is a reasonable source of energy for a

building.

· “Commonwealth Solar Photovoltaic Rebate Program Manual.” Massachusetts Technology

Collaborative. Commonwealth Solar Rebate Program, 8 Oct. 2009. Web. 28 Nov. 2009.

<http://www.masstech.org/renewableenergy/commonwealth_solar/version6/CS_Solicitation_V6_FINAL.

pdf>.

We used this site in order to calculate the grant that would be given to us by the MTC. There was

a great table that outlined how the organization determined how much money would be given for

a certain size system.

· Giudice, Phil, and Carter Well. “Massachusetts is running on solar energy.” Renewable

Energy Trust. N.p., 4 Nov. 2009. Web. 26 Nov. 2009. <http://www.masstech.org/solar/>.

The MTC site gave a great overview of what the organization is able to do. We were able to use

the information provided in our literature review.

· “Average Retail Price of Electricity to Ultimate Customers by End-Use Sector, by State.”

U.S. Energy Information Administration. Department of Energy, 13 Nov. 2009. Web. 15 Nov.

2009. <http://www.eia.doe.gov/cneaf/electricity/epm/table5_6_b.html>.

The Department of Energy provided in this site the price of electricity for Massachusetts. We

used the price of electricity in many of our calculations involving savings in electricity.

· “Cost Of Installed Solar Photovoltaic Systems Drops Significantly Over The Last Decade.”

Science Daily. N.p., 3 Mar. 2009. Web. 15 Nov. 2009.

What we got from Science Daily was the average price of a photovoltaic system. We used the

average price in our calculations of the cost of our photovoltaic system.

· Ramon, San. “A GUIDE TO PHOTOVOLTAIC (PV) SYSTEM DESIGN AND

INSTALLATION.” California Energy Commission. N.p., n.d. Web. 15 Nov. 2009.

<http://www.energy.ca.gov/reports/2001-09-04_500-01-020.PDF>.

The photovoltaic report gave us a lot of data to base our calculations on. What we found from

this report was how many watts per square foot a photovoltaic system is able to produce.

http://www.pvwatts.org/

http://www.masstech.org/renewableenergy/commonwealth_solar/version6/CS_Solicitation_V6_FINAL.pdf

http://www.masstech.org/renewableenergy/commonwealth_solar/version6/CS_Solicitation_V6_FINAL.pdf

http://www.masstech.org/solar/

http://www.eia.doe.gov/cneaf/electricity/epm/table5_6_b.html

36

Windows

Binggeli, Corky. Building systems for interior designers. Hoboken: John Wiley & Sons, 2010.

Print.

The book gives an overview of window treatments and insulation options that are available. The

text also has an in depth analysis on heating and cooling systems as well as

lighting systems.

Boston Shade Company (Boston,MA). Web. 08 Nov. 2009. www.BostonShadeCompany.com

Boston Shade company offers window shade timing system as well as multiple types of

window shades which helped to determine the types of shades.

Energy Information Administration - EIA - Official Energy Statistics from the U.S. Government.

Web. 04 Dec. 2009. <http://www.eia.doe.gov/>.

This web site gives a cost analysis of how much money per ft.3 of natural gas in every state in the

United States. The site also gives the dollar amount per Kilowatt hour of electricity in

Massachusetts. Both of these conversions will help towards the calculations.

Fang, Xiande. "A study of the U-factor of a window with a cloth curtain." Applied Thermal

Engineering 21.5 (2001): 549-58. Science Direct. 2000. Web. 14 Nov. 2009.

<www.elsevier.com/locate/apthermeng>.

This article gave a real study of the affects of curtains, and how they can improve and reduce

heat loss.

"Glass U-Value Performance - SECP Tables - California Glass Bending Corporation." Bent

Glass Home Page - California Glass Bending Corporation. 2007. Web. 03 Dec. 2009.

<http://www.calglassbending.com/secptabl.htm>.

This website gives actual U-values for various glass thicknessess. This helps to give an actual U-

value for the thickness of the Library windows.

Heating & Cooling Degree Days - Free Worldwide Data Calculation. Web. 04 Dec. 2009.

<http://www.degreedays.net>.

This site offers the degree days for specific areas of the United States. The site offers both

heating and cooling degree days which were calculated in Worcester at the Worcester

Airport which is less than five miles away from WPI.

"Home Heating Energy." Test Page for Apache Installation. Web. 13 Dec. 2009.

<http://hyperphysics.phy-astr.gsu.edu/Hbase/thermo/heatloss.html>.

This website offers dergree day calculations. This will allow for a better understanding on how to

calculate heat loss from degree days in the Library

Langdon, William K. Movable insulation : a guide to reducing heating and cooling losses

through the windows in your home. Emmaus: Rodale, 1980. Print.

37

This book offers information on home/ house remodeling. The book also goes into detail about

engineering technology. The author elaborates upon heating, ventilation, cooling,

electricity and windows.

Laouadi, A., M. M. Armstong, A. D. Galasiu, M. C. Swinton, and F. Szadkowski. "FIELD

SUMMER PERFORMANCE OF INTERIOR REFLECTIVE SCREEN." International

Building Performance Simulation Association. International Building Performance

Simulation Association, 30 July 2009. Web. 8 Nov. 2009.

<http://www.ibpsa.org/m_papers.asp>.

This paper offers information regarding window shade efficiency pertaining to building

insulation. Different shade options are proposed throughout the paper and a thorough

analysis is provided. This will help to determine what type of window shade that should

be used for the library.

Leger- Hornby, Tracy. "Library Project." Personal interview. 15 Oct. 2009.

This interview helped the group to get a better understanding of the Library. Tracy introduced

the group to problem of poor insulation around the library, and how looking into that

couls improve the overall efficiency of the library.

"Massachusetts Weather - Average Temperatures and Rainfall." Country Studies. 2008. Web. 14

Nov. 2009. <http://countrystudies.us/united-states/weather/massachusetts/>.

This website gives the average Massachusetts temperatures for every month.

"NFRC - The NFRC Label." NFRC - Welcome. 2005. Web. 14 Nov. 2009.

<http://www.nfrc.org/label.aspx>.

This helped with window and heat loss data for the calculations of the experiment.

SeriousWindows - Energy Efficient Windows & Glass. 2009. Web. 14 Nov. 2009.

<http://www.seriouswindows.com/index.html>.

This website gives a range for which the U-value falls between, as well as gives information

regarding the window treatment.

"The Facts About Windows and Heat Loss." NFRC. National Fenestartion Rating Council, 2005.

Web. 18 Nov. 2009. <http://www.nfrc.org/documents/U-Factor.pdf>.

This website gives information about heat transfer and heat loss through windows

38

Walls "Energy Savers: Insulation and Air Sealing." EERE: Energy Savers Home Page. U.S.

Department of Energy, 24 Feb. 2009. Web. 12 Nov. 2009.

<http://www.energysavers.gov/your_home/insulation_airsealing/index.cfm/mytopic=11220>.

"Non-Energy Benefits of Upgraded Wall Insulation." The Home Energy Saver. Web. 12 Nov.

2009. <http://hes.lbl.gov/hes/hit/nebs/neb_wall.html>.

"Products: Insulated Panels: ESP Wall Panel." Home: IPS offers insusolated panel system

solutions to meet your needs for insulated metal building panels. Web. 05 Nov. 2009.

<http://www.insulated-panels.com/products/esp_wall_panel.html#thermal>.

"Product Knowledge: Window & Door Glossary." Well Done Building Products. Web. 02 Dec.

2009. <http://www.wdbp.com/knowledge/wdglossary/>.

Technology How much electricity do computers use? Oct 2009. 8 Nov 2009 <http://michaelbluejay.com/electricity/computers.html>.

It provides us a way to estimate the cost of the electricity of computer use, by which we can calculate

electricity used on computers.

Library, George C. Gordon. Facts and Figures. 13 April 2009. 4 November 2009 <http://www.wpi.edu/Academics/Library/About/facts.html>.

This webpage is an official website of Gordon Library, from which we can get some general information

about the library, including the numbers of computers and TVs. Only when we have the statistics of the

stuffs can we estimate the cost of the electricity.

Martin. 7 Computer Energy Saving Tips. 8 Nov 2009 <http://www.ghacks.net/2009/05/29/7-computer-energy-saving-tips/>.

Here are several tips on saving the electricity of PCs. We may get some suggestions from it.

Minimize Your Computer's Energy Use. 2006. 8 Nov 2009 <http://cc.uoregon.edu/cnews/winter2006/energy_use.htm>.

Here are some tips on minimizing computers' energy use, which can contribute to our proposal.

NAIMA. "Comparing Fiber Glass and Cellulose Insulation." Aug 2009. North American Insulation Manufactures Association. 4 Nov 2009 <http://www.naima.org/pages/resources/library/pdf/BI475.PDF>.

This document compares the fiber glass and cellulose, two popular insulations, in several aspects

including thermal resistant r-value, settling and loss of r-value, water vapor sorption, natural convection,

39

safety, and so on. This article not only provides us the information about these insulation products but

also teaches us a way to analysis various kinds of insulation.

—. "Facts About Fiber Glass Loose-Fill Insulation." March 2006. NAIMA. 4 Nov 2009 <http://www.naima.org/pages/resources/library/pdf/BI456.PDF>.

Loose-fill insulation is a kind of insulation that can be installed based on the existing wall, which can be

taken into consideration as a way to deal with the insulation problem in the library.

—. Residential and Commercial Insulation Applications. 4 Nov 2009 <http://www.naima.org/pages/products/bi.html>.

It gives some suggestions about properties and installation of fiber glass and rock and slag wool building

insulation, which makes us know about ways to construct insulation to library's wall.

Saver, Energy. Blanket (Batt and Roll) Insulation. 24 Feb 2009. 4 Nov 2009 <http://www.energysavers.gov/your_home/insulation_airsealing/index.cfm/mytopic=11520?print>.

Blanket insulation is the other practical insulation product for the existing wall. We can use the

information to compare with loose-fill insulation to figure out the best way.

—. Loose-Fill Insulation. 24 March 2009. 4 November 2009 <http://www.energysavers.gov/your_home/insulation_airsealing/index.cfm/mytopic=11650>.

Loose-fill insulation is probable practical insulation product for the existing wall. We can use the

information to compare with blanket insulation to figure out the best way.

—. Sprayed-Foam and Foamed-In-Place Insulation. 24 February 2009. 4 Nov 2009 <http://www.energysavers.gov/your_home/insulation_airsealing/index.cfm/mytopic=11700?print>.

Sprayed-Foam and Foamed-In-Place insulation is another method we may look into.

—. Types of Insulation. 24 March 2009. 4 November 2009 <http://www.energysavers.gov/your_home/insulation_airsealing/index.cfm/mytopic=11510?print>.

This website provides us an introduction about types of Insulation, from which we can find out what we

need to look into.

—. Where to Insulate in a Home. 24 February 2009. 4 November 2009 <http://www.energysavers.gov/your_home/insulation_airsealing/index.cfm/mytopic=11380>.

This article give some instructions about installing the home, which can apply to the library.

40

Savers, Energy. Storm Doors. 24 Feb 2009. 4 Nov 2009 <http://www.energysavers.gov/your_home/windows_doors_skylights/index.cfm/mytopic=13630?print>.

Storm doors can be applied to those existing yet old doors, contributing to strengthening the insulation

of the library.

—. When to Turn Off Personal Computers. 30 Oct 2009. 4 Nov 2009 <http://www.energysavers.gov/your_home/appliances/index.cfm/mytopic=10070?print>.

This offers general information about the use of electricity of computer in various modes including

sleeping, off, hibernation, from which we may figure out how to use computers in library in a most

efficient way.

—. Window Treatments and Coverings. 24 Feb 2009. 4 Nov 2009 <http://www.energysavers.gov/your_home/windows_doors_skylights/index.cfm/mytopic=13500?print>.

This provides some suggestions to add insulation for the window, which we also need look into.

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