PVSN Energy
Decision Tool
Overview and instructions
A general overview of the tool is
given below, followed by general usage instructions. More detailed information
on the tool can be found in Section 5 of the thesis document
General overview
This tool is designed to provide
information on the environmental, health, and financial costs and benefits of
implementing green energy options for your building. It is currently implemented in an Excel
spreadsheet.
How it works
You answer a few questions related
to your current energy use (such as type and amount of energy, and related
replacement and maintenance costs) and then select alternative green energy
options to evaluate. The tool uses
default values based upon typical energy costs to generate a comparison of the
proposed options with your current situation.
Why implement green energy options?
Through implementing green energy
alternatives, you can improve the environment and possibly save money. Energy
efficiency and alternative energy options reduce emissions of greenhouse gases,
such as carbon dioxide, and of other pollution emissions, such as sulphur
dioxide. Reducing greenhouse gases helps
to reduce the risk of climate change; climate change may result in rising sea
levels (affecting loss of homes and farmland), more dramatic weather extremes
(e.g., drought in some areas, floods in others, more intense storms, more heat
waves, resulting in loss of life and
property, and an increase in infectious diseases), form imbalances in ecosystems , and affect
the types of crops grown in different parts of the world (leading to hunger in
some countries). Reducing other pollution
emissions has positive health effects for yourself, your community, and the
local environment. Health issues affected by pollution emissions include
premature mortality, hospital & ER visits, asthma attacks, and lost work
days. Local pollutants also impact the
environment, for example local traffic and inefficient wood burning stoves
contribute to particulate matter concentrations (resulting in an increase in
respiratory complaints), and size of homes impacts the demand for heating.
Finally, many of the options will save you money in the long run, and protect
you from fluctuations in energy prices.
Green Energy Options impact (Output)
The output of the tool is a
comparison of your proposed changes to your current situation in terms of
emissions, health, and personal financial impact. Emissions are calculated in
tons of CO2, SO2, and NOX. Health impact
is calculated in number of incidents of premature mortality, hospital & ER
Visits, Asthma Attacks, Respiratory Symptoms and work loss days.
The tool makes it easy to make the
comparison by associating a monetary value with the health and emissions
impacts. In economic terminology, the health and emissions-related costs to the
community are commonly referred to as societal costs. The tool generates an overall
cost for your current situation and the proposed options by combining an
estimate of your personal financial cost and the societal cost. For your
particular situation, some energy options will directly save you money, as well
as benefit society, resulting in an overall net benefit. Some options may not
directly save you money, but will have a positive societal financial benefit;
the net overall result will depend on the relative magnitude of your cost and
the societal benefit. [See examples of such
outcomes in section 5.6 of the thesis document
using the tool
This section provides a quick overview on using the
tool. A detailed explanation of the tool
can be found in Section 5 of the thesis document
. The detailed explanation includes
underlying formulas and assumptions that are made in the development of the
tool.
The “interface” tab is where all user data is entered, as
well as where the results are displayed.
The other tabs are work tabs in which supporting data is stored and
where the underlying calculations are done.
User entry cells are
color coded in the Excel spreadsheet.
They are yellow
for your existing situation and green for alternative energy options. Data entered as drop down
boxes is in white for both existing and alternative options (for an example see
the “Heating Fuel Type” choice below).
Example input fields for existing situation

Example input fields for Green energy options

Some User entered fields have “help” associated with them
via Excel comments. They have a red
triangle in the upper right hand corner of the cell description; for example,
in the figure above, the red triangle in the Photovoltaics, Panel Selection and # of panels fields indicate
there is additional information provided for these fields. Hover your cursor over the cell in Excel to
see the comment/”help” information.
Click to see what Information you need to provide
Click to hide what Information you need to provide
You will be asked to provide the following information for you current
situation:
Parameter
|
Description
|
Annual
Electrical Load
|
Enter the amount of electricity used on
an annual basis, in kilowatt hours (KWH).
This
information can be estimated from electric utility bills. You may need to
extrapolate monthly information to determine the annual amount.
The
average annual household electricity usage in Massachusetts in the year 2007,
as per the EIA (Energy Information Administration) is 7650 KWH (635
KWH/month).
http://tonto.eia.doe.gov/ask/electricity_faqs.asp#electricity_use_home
|
Heating Fuel Type
|
Select the
primary type heating fuel you currently use to heat your home from a menu of
None, Oil, Propane, Natural Gas, and Electric.
As per the EIA,
the main type of heating fuel used in the New England Census
Region in 2005 by percentage was:
Natural Gas:
44%
Electricity 6%
Fuel Oil: 46%
Other: 4%
|
Annual Heating Fuel use
|
Enter the
amount of the selected heating fuel you use in a year.
Look to
utility bills for an estimate.
Averages used for New England in 2005 as per EIA
(Energy Information Adminstration) are:
Electricity: 2434 KWH (Kilo-Watt Hours)
Natural Gas:
740 therms
Fuel Oil: 739 gallons
Kerosone (gallons):
Not Available
LPG (gallons): Not Available
NOTE for ELECTRIC heat: If you choose Electric for
fuel type this value is not used.. Instead, heating
is assumed to be 44% of your total electrical utilization . You can change
the percentage of electricity used for heat on the “Utility Use” tab.
|
Efficiency current heat unit:
|
Enter the
efficiency of your heating unit.
If you know your heating unit's efficiency, enter it
here. If you do not know it, enter one
of the following:
Oil:
0.8
Natural Gas:
0.8
Propane:
0.8
Electric:
0.9
Guidelines to use:
Equipment installed prior to 1992: .7
Medium efficiency equipment: .8
High efficiency equipment: .9
A heating unit's efficiency is measured by annual
fuel utilization efficiency (AFUE)
In general, oil, natural gas, and propane equipment
prior to 1992 was fairly inefficient (in the 68-72% range). EPA requirements for new equipment have a
minimum AFUE of 78%, with high efficiency
heaters having AFUEs as high as 97%.
NOTE: Home-builders tend to install lower-end
equipment (in the 80% efficiency range).
|
Annual Maint Cost
|
Enter the
amount you expect to pay per year to maintain your current heating system.
Annual maintenance cost is commonly in the form of a
service contract. Service contracts
vary in price and in what they cover.
For example, a basic service contract may include an annual tune-up to
increase system longevity and performance; emergency service; and parts and
labor for some types of repairs.
The default amount of $225 used in the tool is based on
browsing rates posted on area provider
websites (NOTE: many providers do not post rates on their websites).
|
Remaining life (yrs)
|
Enter the
number of years remaining until you expect to replace your current heater.
The expected useful life of heating equipment is 15 -25 years Subtract the current age of your furnace
from 20 to determine the remaining life.
NOTE: You
may be able to determine the installation date of your furnace from the
nameplate data.
|
Replacement cost
|
Enter the
amount you would expect to pay for a new heating system.
Enter the amount you would expect to pay if you had
the heating system installed today.
That is, enter the amount in today’s dollars even though you may
actually be installing the system at some point in the future. The tool does
comparisons in today’s dollars.
The cost of new heating systems varies. See the link below; it provides some
general cost information which can be used as guidelines.
http://www.costhelper.com/cost/home-garden/furnace.html
|
Water Heating Method
|
Select water heating method from a menu of None,
Same as Heating Fuel, and Electric.
|
House Square Footage
|
Enter the
square footage of the living space of your building.
For single family detached homes in New England, the
average heated space is 2154 square feet (enter the corresponding value for
your building).
As a reference point, the average total space
(including attached garages, basements, finished attics, and enclosed
porches) is 2472 square feet, according to the EIA’s 2005 Residential Energy
Consumption Survey. However, enter
only heated space here.
|
Type of Building
|
Select from
menu of Residential and Commercial.
|
Number of Occupants
|
Enter the
number of occupants in your building.
The average household size for New England is 2.33,
according to the EIA's (Energy Information Administration) 2005 Residential
Energy Consumption Survey.
|
Discount Rate
|
Enter the rate
at which you want to discount future costs.
If unsure, leave the default 0.05.
A higher discount rate will put more emphasis on immediate returns,
while a lower discount rate implies a more long term perspective.
|
Click to see what Green Energy Options are Available to you
Click to hide what Green Energy Options are Available to you
Select from the following Green energy options:
Compact Fluorescent Lighting
|
|
# to Replace
|
For a given wattage level,
enter the number of incandescent light bulbs you intend to replace with
compact fluorescent light bulbs.
|
Frequency of bulb use
|
Select the option that best
characterizes how long during the day the light bulbs are in use.
Frequent = more than 6 hrs
Moderate = between 1 and 6
hours
Infrequent = a half hour or less
|
|
|
Refrigerator Replacement
|
Replace your standard
fridge with Energy Star fridge of similar size
|
Fridge Size
|
Choose from:
·
small (15.4 cubic
feet)
·
medium (18.41 cubic
feet)
·
large (25.41 cubic
feet)
|
windows
|
|
Current Windows
|
Select the type of windows
currently installed on your building
·
Single Pane
·
Double Pane
·
Double Pane Low-e
|
Type of new windows
|
Select the type of windows
you'd like to install on your building
·
Single Pane
·
Double Pane
·
Double Pane Low-e
|
Number of windows to
replace
|
Specify the number of
windows to be replaced.
|
insulation:
Roof/Ceiling
|
|
Area (ft^2)
|
Enter the square footage of
the ceiling or roof area you intend to insulate
|
Current Insulation Type
|
Select the insulation level
that best describes the current insulation in the roof/attic of your current
structure. The tool will display
associated R-values.
Select from:
·
No Insulation
·
Poorly Insulated
·
Moderately Insulated
·
Well Insulated
|
Update Insulation to:
|
Select the level to which
you will update the insulation in the roof/attic of your current
structure. The tool will display
associated R-values.
·
Moderately Insulated
·
Well Insulated
|
INSULATION:
Wall
|
|
Area (ft^2)
|
Enter the square footage of
the wall area you intend to insulate.
|
Current Insulation Type
|
Select the insulation level
that best describes the current insulation in the walls of your current
structure. The tool will display
associated R-values.
Select from:
·
No Insulation
·
Poorly Insulated
·
Moderately Insulated
·
Well Insulated
|
Update Insulation to:
|
Select the insulation level
that best describes the current insulation in the walls of your current
structure. The tool will display
associated R-values.
·
Moderately Insulated
·
Well Insulated
|
Solar Technologies: Photovoltaics
|
Roof or ground mounted solar panels, which
convert sunlight to electricity.
|
Panel Selection
|
Select a panel type to add
to your building. Panels differ by
wattage, efficiency, and price.
|
# of Panels
|
Enter the number of panels you'd like to add to your
house. The tool displays descriptive
information regarding your selection.
|
|
|
Solar Technologies: Solar Hot Water
|
Roof or ground mounted solar panels, which
convert sunlight to electricity.
|
Solar Hot Water
|
Solar hot water systems use
heat from the sun to provide hot water to a building. Selecting "yes" will cause this
tool to automatically select a system size, based on number of occupants.
|
Solar Technologies: Daylighting
|
Daylighting combines the use of skylights
and electric lighting controls to maximize natural light and minimize
electric lighting.
|
Sq Ft of daylit rooms
|
Enter the total square
footage of rooms you want to consider for daylighting.
|
Number of skylights
|
Select the number of
skylights to install. If "0"
is the only option, more square footage is required for daylighting to be
effective.
|
Heating Technology
|
User entry fields in this
section are dependent on the selection the user makes for heating technology
|
Heating Technology
|
From the drop down list,
choose the heating technology you wish to evaluate. Choices are:
·
Geothermal
·
Biomass
·
Biofuel
|
GEOTHERMAL
|
Geothermal heating makes
use of consistent subterranean temperatures to heat a building. These systems require the excavation of a
well.
|
Geothermal:
System Size
|
Choose a system size:
·
3 ton
·
4 ton
These are the most common
sizes for residential and small business systems.
NOTE: 1 ton = 12,000 BTU/hr
|
Well Cost
|
Geothermal heating requires
a well. If you already have a well,
enter 0. Else, enter the expected cost
to dig a well.
|
|
|
BIOMASS
|
Biomass heating uses the
combustion of wood to heat a home. In
this case, we consider a wood boiler that uses cordwood as fuel.
|
Biomass:
System Size
|
Choose from:
·
Small boiler
·
medium boiler
·
large boiler
|
BIODIESEL
|
Biodiesel is a vegetable
based biofuel. It can be burned by an
oil burner without the purchase of new equipment. If you do not currently use oil, new
equipment must be installed. The fuel
blends are:
B5: 5% biodiesel, 95% #2
oil
B20: 20% biodiesel, 80% #2
oil
B100: 100% biodiesel
These blends differ in
price and emissions.
|
Biodiesel: Fuel Typed
|
Choose the type of of
biodiesel fuel from the following list:
B5:
B20:
B100:
|
|
|
Tool Output
The tool output is a
comparison of the benefits of your proposed options to your current
situation. The tool compares financial,
emissions and health impacts.
Sample output is shown below for a household replacing 10
moderately used 75 W light bulbs with compact fluorescent bulbs. In addition to an annual cost savings of
$58.75 per year, the tools shows annual society benefits of $11.30 for
emissions and $28.48 for health impact.
