Master of Science – Sustainability in the Urban Environment Economics of the Environment and Natural Resources Professor Kevin Foster
2011 Homeowner's Handbook for Energy Conservation
David Turner
I
Bishoy Takla
Contents Introduction .................................................................................................................................................. 2 Windows ....................................................................................................................................................... 4 Non-solar heat flow ...................................................................................................................................... 5 Recommendation for selecting window U-value........................................................................................ 10 Solar Gain .................................................................................................................................................... 10 Recommendation for selecting SHGC ......................................................................................................... 13 Ventilation and Airtightness ....................................................................................................................... 13 Preventing condensation ............................................................................................................................ 15 Daylighting .................................................................................................................................................. 16 The NFRC Label ........................................................................................................................................... 16 Cost analysis ................................................................................................................................................ 17 Passive Systems: ......................................................................................................................................... 23 Landscaping for Energy Efficiency:.............................................................................................................. 23 Winter: ........................................................................................................................................................ 24 Summer: ...................................................................................................................................................... 31 All Seasons: ................................................................................................................................................. 35 Cost Analysis: .............................................................................................................................................. 36 Market Incentives: ...................................................................................................................................... 41 References: ................................................................................................................................................. 43
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Introduction Would you drink out of a leaky glass or water your plants with a leaky pale? No, you wouldnâ€&#x;t because it is counterproductive to your task of effectively drinking and watering. So why are we living in homes that allow heat to escape in the winter and cool air to escape in the summer if our task is to efficiently regulate the temperature inside our homes? Because we canâ€&#x;t physically see the heat from our boilers or the cool air from our air conditioners actually flow out of the various crevices that need to be plugged the way that you can see water flowing out of a
Figure 1: Analogy comparing water loss from a bucket to heat loss in a building
bucket with holes in it (Figure 1).
In this handbook, we are going to focus on improving the thermal envelope and supplement with passive systems as a retrofit to existing homes. By improving the thermal envelope, we will reduce the dependence on electricity and mechanical heating systems. Passive systems will aid the thermal envelope solutions by reducing that dependence as well (Figure 2).
Figure 2: Three tier system to reduce home energy consumption
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The purpose of this handbook is to introduce a few methods to reduce oneâ€&#x;s dependence on conventional heating, cooling, and lighting by effectively enclosing the thermal envelope and passively making the most out of the microclimate for the average homeowner within the New York City metropolitan area (Figure 3). We will explain how these methods will reduce oneâ€&#x;s consumption and lower their utility bills. Specifically we will look at reduction of natural gas consumption and costs for heating in the winter, reduction of electricity consumption and costs for cooling in the summer, and reduction of electricity consumption and costs for lighting year round. Some questions we hope to answer include: How can these methods reduce consumption for the average New Yorker? How much money and energy can be saved in the long run? What is the return-on-investment? Is it worthwhile for me to implement these energy saving solutions?
Figure 3: Diagram showing heat loss and gain throughout a building
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Windows As mentioned in the introduction, the main goal of this paper is to improve the efficiency of your home, and respectively decrease your monthly bills. You might wonder why we started out by talking about improving your windows. Basically your windows are the weakest thermal link within your home (Figure 4). Single pane windows have no thermal resistance at all, and all its resistance is due to the surface air film (Lechner, 2009), therefore selecting the right type of window for your home is a harder job than it may seem. Many factors impact the right choice; energy related and non-energy related. We are going to discuss in this section how to choose the right type of windows for your home, what is the future technology for windows, and how long is the payback period for your choice.
5% through ceilings
16% through windows
17% through frame walls
1% through basement floor
3% through door 38% through cracks in walls, windows, 20% through and doors basement walls
Figure 4: losses of heating energy through house element
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Energy flow occurs through windows in three different forms (Figure 5): 1- Non-solar heat loss or gain, in form of conduction, convection and radiation, which is a factor of the temperature differences between inside and outside. 2- Solar heat gain in the form of radiation, which is desirable during the heating session and undesirable during the cooling session. 3- Heat loss through ventilation (intended air changes) or infiltration (unintended air changes through cracks and joints), which we will need to minimize as much as possible. Non-solar heat flow The main reason for heat flow (loss or gain) is the temperature difference between indoor and outdoor. The thermal energy always seeks an equilibrium situation. In winter time, your windows lose heat to the outside freezing air in order to achieve this equilibrium state. The opposite happens in the summer months when the air-conditioned indoor air gains heat from the outside hot air. In order for us to minimize this natural flow of air, we need to minimize the windows thermal conductance, which is called the U-value. U-value is a measure of the amount of non-solar heat flow through a window (or other material), expressed in Btu/hr-sf째F. U-values tell us how well a window will allow heat to pass through it. A lower Uvalue means less heat flow. The lower the U-value, the greater a product's resistance to heat flow and the better its insulating value. U-factors allow customers to compare the insulating properties of different windows. The area of the window also affects how much heat flow can pass through Figure 5: The energy flow occurs through windows in three different forms
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it. The bigger the window is the more heat flow will pass through it. The mathematical formula that expresses these factors is: Q = U-value x Area x Delta T Where U is the U-Value of the window (including the frame) in Btu/hr-sf°F, A is the window area in SF, and Delta T is the temperature difference between the inside and outside temperature in degree Fahrenheit. This formula is very useful to calculate the heat flow through a window at a specific moment in time. However, we are more interested in calculating the total heat flow during the whole session or even the whole year. Thus, we need to use the Heating Degree Day (HDD), which is the number of degrees that a day's average temperature is below 65 °F. For example, NYC temperature on January 21st had a high temperature of 32 °F and a low temperature of 18 °F with a mean temperature of 25 °F. The HDD calculation for this day is 65-25= 40. HDD is a measurement designed to reflect the need for energy to heat your home. In the same way, summer Cooling Degree Days (CCD) are the number of degrees that a day‟s average temperature is above 65 °F, which are the degrees that need to be removed from the home in order to achieve thermal comfort (65°F). HDD and CDD are widely available for each specific location. You can use www.nyserda.org to see the HDD for your city. Table 1 shows the HDD and CDD for NYC. As you can see, the HDD is greater than the CDD because NYC is a heating climate.
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Table 1: HHD and CDD for NYC.
Now how can we improve the windowsâ€&#x; U-value? Windows are the weakest thermal point in your home (Figure 6). For example, to reach the same thermal resistance as a conventional insulated stud wall (R-14), it would take about 13 sheets of glass and 12 air spaces in between them (Figure 7). The U-value for a single pane window is mainly due to the thin film of air on the interior and a layer of air on the exterior, which is about 0.61 and 0.17 (hsf°F/Btu) respectively. By adding an extra layer of glazing to your window you are adding the U-value of the glass itself as well as the U-value of the air in between. Moreover, the space between the panes can be filled with gas instead of air. Some gases have more thermal resistance than air.
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Argon, Krypton, and Sulfur Hexafluoride are the most common gases used for this purpose. It only adds a few extra dollars into the total price but adds a great value to the windowâ€&#x;s U-value.
Figure 6: infrared picture for a home illustrates the amount of heat that flows through windows (represented in red).
Furthermore, adding a microscopically thin layer of metallic oxide coating can dramatically increase the window resistance. The low – emittance (low-E) coating reflects the radiative heat back into your home during the heating season and reflects unneeded solar heat to the outside during the summer. The coating usually is applied to the interior face of a multi-pane window to protect it from weather and cleaning conditions. Likewise, the frame and the spacer, which separate the multipane (Figure 7), have a great impact on the overall U-Value of the window. Research shows that a double pane with a metal spacer has
Figure 7: window spacer
almost the same U-factor as a single pane of glass (DOE, 1997). Spacers made of aluminum and steel are not recommended because of their low thermal performance. The fiberglass and foam Page 8 of 47
spacer are recommended because of their higher thermal performance. Window frames made of wood, fiberglass, and vinyl are better insulators than metal or aluminum frames. However, some new metal and aluminum frames are designed with internal insulation to break the metal thermal bridges, which increase resistance and improve performance (Figure 8). Table 2, which is from the ASHRAE hand book, shows representative U-factors for glazing, spacers, and frames and their impact on the overall UValue.
Figure 8: Window frame with internal insulation to improve the window U-Value
Table 2: U-Factors for glazing, spacer and frame and its impact on the overall U-Value
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Recommendation for selecting window U-value To assign the correct U-value to your new windows, make sure that the manufacturer specifies this value for the whole window (glazing, frame and spacer) not just the glazing value. The frame and spacer might increase the U-value of the window and decrease its efficiency. Avoid metal frames unless they have internal insulation to break the thermal bridges. For maximum insulating value, wood, vinyl, and fiberglass are the suggested frame materials. Single pane is not permitted by most local building codes. Double pane windows are the minimum requirement. Low-E coating with gas filled windows are recommended for their higher insulating value with insignificant increase in cost. Triple pane for south facing windows is advisable. In short, the U-value should be no more than 0.4 at any window in order to ensure mean higher insulation values and lower utility bills. Solar Gain In winter, windows can provide your home with free heating energy but can also cause overheating during the summer. Our goal is to maximize the winter solar gain (free heat) and minimize the summer solar gain (overheating). The first part is easily achievable by having bigger window sizes. However, this will also minimize the summer heat, which is the dilemma. In fact, solar transmission through windows accounts for 30% of the cooling requirements in some regions (DOE, 2008). The solar heat gain of a window depends on its solar heat gain coefficient (SHGC). SHGC is a measure of the rate of solar heat flowing through a window. The orientation of the window has a great role in the total solar gain. Figure 9, shows the different heat flow through a 1/8� clear single pane window in different orientations. For example, when looking at figure 9, the south facing windows have potentially the highest, most beneficial solar heat gain during the winter season and has a lower gain during the summer time, Page 10 of 47
thus south facing windows are the most important for solar heat gain. High SHGC windows can be used to maximize the winter gain, and shades can be used to minimize the summer gain.
Figure 9: solar heat gain through 1/8� clear single pane window during the summer and winter sessions
In contrast, the east and west windows are penalized twice (Figure 10). They lose solar heat gain in winter and gain more solar heat in summer. This is because the sun seldom shines straight through east and west facing windows in the winter, but shines powerfully on these facades in the morning and afternoon during the summer. West facing windows are mostly challenging in summer time because they gain more heat during the afternoon (sunset), which is the hottest time of the day. Besides, east and west windows are hardly shaded because the sun angle is very low (Figure 11). Thus, east and west windows must be minimized and carefully designed. A lower SHGC window can be used to improve heat-efficiency. On the other hand, north facing windows are mostly useful for day lighting. Unlike the others, northern windows provide a comfortable indirect light source which reduces the need for electric lights. Page 11 of 47
Figure 10: The summer sun angle is higher than the winter sun angle. The east and west sun angles are very low all year round.
Figure 11: Bigger incidence angle during the summer reflect most of the solar heat gain
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Recommendation for selecting SHGC Window SHGC should preferably be designated according to the orientation. South facing windows should have a higher SHGC to maximize the winter gain. This gain will not usually result in overheating in the summer because of the sunâ€&#x;s greater incidence angle during the summer (Figure
Figure 13: Winter and summer sun angles
12). East and west windows should have low SHGC because they transmit solar heat gain during the summer. Northern windows donâ€&#x;t face direct sunlight, therefore there is no need to spend extra money to improve north facing windows. The northern windows should be operable to provide cross Figure 12 : Cross ventilation
ventilation with south facing windows (Figure 13 and Table 3). Table 3: Recommendation for U-Value and SHGC
U-Value Less than 0.32
South East and West North
SHGC Higher than 0.40 Lower than 0.3
Recommendations Higher SHGC to maximize solar gain in winter Double glazing and minimum sizes Operable to provide cross ventilation
Ventilation and Airtightness The use of windows to ventilate your home is a very old architectural concept yet very effective. Nearly all historic buildings were ventilated naturally, although many of these have been used partially with mechanical systems. Recent awareness of the environmental impacts and costs of energy has encouraged natural ventilation. Table 4 shows different window types
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and their effective open area for ventilation. Casement windows are effective for ventilation because they direct the greatest fresh airflow into the living space when fully open. Table 4: representative window ventilation areas
Infiltration is the unintended air change around the window through joints and cracks. This leakage accounts for about 10% of the energy used in the home (DOE). The tightness of the window depends on the window quality as well as its proper installation. A window with a compressing seal such as a casement window is more airtight than a regular sliding seal. Air tightness rates are given in cubic feet of air passing through a square foot of window area per minute (cfm). The minimum requirement is 0.37 cfm/sf (Oregon Residential Energy Code, 2008- DOE). Operable windows can be used during fall and spring to reduce the need of air conditioning as well as provide ventilation; they are
Figure 14: apply caulk to all edges where window frame meet the wall
often specified to meet egress code requirements. Assign lower airtightness values at windy sites or other harsh climates in order to achieve an ideal airtightness level, and make sure that it is well insulated. Check all the seals and edges Page 14 of 47
where the window frame meets the wall and carefully seal and caulk all joints and cracks (Figure 14). Preventing condensation Improving your windows will not only reduce your utility bills but will also save you a lot on your maintenance expenses. The energy efficient window can prevent condensation to occur on the interior of your home, which helps prevent dangerous issues such as mold. Air holds various amounts of water vapor, which is correlated to the air temperature. Cold air holds less water vapor than hot air. The amount of moister in the air is expressed in the ratio between the amount of moisture in the air to the total amount of moisture that the air can hold. This is called relative humidity (RH). The RH increases when the air is being cooled because cold air can hold less moisture than hot air, making the existing moister level a higher percentage of what the air can hold (Lechner, 2009). When RH reaches 100%, the air canâ€&#x;t hold any more moisture causing condensation. When moist air faces a cold surface, like your old windows, the air will be cooled, which decreases its ability to hold moisture causing water to condense on the surface of your window, similar to what happens to a cold glass of water in hot temperature. Condensed water can damage window frames, sills, and interior finishing. In severe cases it might damage the insulation and wood framing. On the other hand, air that comes in contact with your new energyefficient window is less likely to condense and cause those damages because window surface will not be cold, due to its higher insulation value.
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Daylighting Windows can help you reduce the demand for artificial lighting, but at the same time, they cause significant solar heat gain during summer months. Simple solutions to reducing solar heat gain, such as tinted glazing or shades, can reduce daylighting as well. New glazing with special low-E coating can provide better solar heat gain reduction with a slight loss of visible light. This characteristic is measured in visible transmittance (VT). VT measures how much light flows through your window. VT is an optical property that designates the quantity of visible light transmitted. It is expressed as a number between 0 and 1. Higher VT value means more transmitted visible light through the window. The NFRC Label The National Fenestration rating Council (NFRC) is a nonprofit, private organization who provides prospective window shoppers with a standard rating system between various windows. Figure 15 shows an NFRC label. The most important numbers are the U-value and SHGC.
Figure 15: NFRC window label
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Cost analysis Now that we have covered the various methods and benefits of different characteristics of windows for energy efficiency, letâ€&#x;s come up with a specific design for the average homeowner in the New York metropolitan area and figure out the return-on-investment. In order to optimize energy efficiency, we will replace the current south facing windows with a triple glazing, low-E coating windows with lower U-value and higher SHGC. East and west facing window will be replaced with double glazing, low-E coating and gas filled windows with a lower U-factor and a very low SHGC. The northern windows will be replaced with operable double glazing windows. For this case study I will assume that all of the old windows are single pane with U-values of 0.5 and SHGC of 0.75. In a heating climate such as the New York Metropolitan area, windows could be a major source of heat loss. However, after applying the previous proposed solutions to your home we can prevent the majority of the heat loss. The table below (Table 5) illustrates the significant savings in heating and cooling costs. In order to calculate the non-solar heat flow, I used the formula: Q = U x A x HDD where U is the difference between the old and new windowsâ€&#x; U-value. I assumed the old Uvalue for all old windows to be 0.5, thus the difference was 0.25 for the southern windows, 0.18 for the eastern and western windows and 0.1 for the northern windows. A is the area of the window and HDD is the heating degree day for New York City Table 1. In order to get the value in Btu/hour, I multiplied the result by 24 (hour/day). The total non-solar heat flow for all windows was 371 $/year.
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Table 5: Non-solar heat flow saving
Winter South
East 0.25 20 4227 21135 507240 4 2028960 594.654 130.824
Difference in U-Value Area HDD Btu/day Btu/hr Number of window Btu/ hr K Watt Total Saving
West 0.18 20 4227 15217 365213 2 730426 214.08 47.097
North 0.18 20 4227 15217 365213 2 730426 214.08 47.097
0.1 20 4227 8454 202896 3 608688 178.4 39.247
Total Winter saving 264.00 $/year Summer South Difference in U-Value Area CDD Btu/day Btu/hr Number of window Btu/ hr K Watt Total Saving
East 0.25 20 1712 8560 205440 4 821760 240.844 52.9857
West 0.18 20 1712 6163.2 147917 2 295834 86.704 19.075
North 0.18 20 1712 6163.2 147917 2 295834 86.704 19.075
0.1 20 1712 3424 82176 3 246528 72.253 15.896
Total Summer saving 107 $/year Total non-solar heat flow saving 371 $/year
Now, it is time to calculate the solar heat gain in the winter. We can use the flowing equation to do that:
Q= SHGC x A x SHGF
Where SHGC is the difference between the old and new windows Solar Heat gain Coefficient, A is the window area, and SHGF is the solar heat gain factor, which varies for each month and for
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each location. Table 6 shows SHGF for NYC. From the table below, the total savings from capturing solar heat gain in the winter is $230/year. Table 6: Calculating solar heat gain
Building Characteristic Glass Different Faรงade old SHGC Area SHGC (sf) 0.75 North 30 0.36 East 10 0.56 West 10 0.56 South 40 0.22 Monthly Solar Radiation Values, New York City (kBtu/sf) Faรงade Jan Feb Mar Apr May North 4 6 9 10 15 East 10 15 22 27 32 West 13 15 23 25 30 South 30 29 33 29 27 Monthly Solar (kBtu) Heat Gains Faรงade Jan Feb Mar Apr May North 48 65 99 110 161 East 59 85 122 149 179 West 71 82 126 140 170 South 262 257 287 257 237 total heat gain Jan Feb Mar Apr May 440 489 635 656 748
Total Winter gain
Kbtu/hr
Kwatt
$/year
3,575
1048
230
Jun 15 31 30 24
Jul 16 35 32 27
Aug 12 31 27 30
Sep 9 25 23 33
Oct 7 19 20 34
Nov 5 11 12 25
Dec 4 9 10 23
Jun 164 176 170 215
Jul 175 195 179 234
Aug 134 174 153 265
Sep 96 142 131 290
Oct 79 105 112 301
Nov 55 64 66 220
Dec 48 50 53 204
Jun 725
Jul Aug Sep Oct Nov Dec 783 725 659 597 405 355
From the previous calculation, the total saving from non-solar heat flow and solar heat gain is $601/year. Table 7 shows the estimated initial cost to replace your old windows with more energy efficient windows. Since most of the manufactures estimate their prices on a case by case basis, the proposed cost estimating was verbally verified from an experienced consultant Page 19 of 47
in the efficient window field. The total estimated cost is $10,980. Besides, there will a maximum amount of $200 tax credit for energy efficient windows. Table 7: Proposed cost estimation
South Triple glazing window
Window type
East and West Double glazing, low-E coating and gas filled window 2 Marvin 4‟ W x 5‟ H Low-E Argon Casement Vinyl Window - 3/4″ IG − LoĒ2 272R − Argon − GBG
North Double glazing window
Quantity Specification
4 Marvin's 5‟ W x 4‟ H triple-glazed window Wood Ultimate Casement Collection
U-value SHGC VT Condensation resistance Supply
0.25 0.39 0.47 65
0.32 0.19 0.44 58
0.40 0.53 0.56 43
$50 per SF $1000.00 each $200.00 each $1200.00
$38 per SF $760.00 $175.00 each $935.00
$23 per SF $460.00 $150.00 each $610.00
$4800.00
$1870.00
$2440.00
Installation Supply $ installation Total Total cost $ 10,980
3 Marvin 4‟ W x 5‟ H double pane Casement Vinyl Window 3/4″ IG − Air
Graph 1 illustrates the payback time and the consumption per year. The calculated payback time for all windows improvement is about 18 years. 1 4740
2 9480
3 14220
4 18960
5 23700
6 28440
7 33180
11 52140
12 56880
13 61620
14 66360
15 71100
16 75840
17 80580
21 99540
22 104280
23 109020
24 113760
25 118500
26 123240
27 127980
8 37920
9 42660
10 47400
18 85320
19 90060
20 94800
28 132720
29 137460
30 142200
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31 146940
32 151680
33 156420
34 161160
35 165900
1 14918.2
2 19056.41
3 23194.61
4 27332.82
5 31471.02
6 35609.22
7 39747.43
8 43885.63
9 48024
10 52162.04
11 56300.24
12 60438.45
13 64576.65
14 68714.86
15 72853.06
16 76991.26
17 81129.47
18 85267.67
19 89405.87
20 93544.08
21 97682.28
22 101820.5
23 105958.7
24 110096.9
25 114235.1
26 118373.3
27 122511.5
28 126649.7
29 130787.9
30 134926.1
31 139064.3
32 143202.5
33 147340.7
34 151478.9
5
10
35 155617.1
180000 160000 140000
Consumption
120000 100000 80000 60000 40000 20000 0 0
15
20 Years
25
30 35 40 Consumption withouth window ‌
Graph 1: Payback time for window improvement
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The initial investment might be an obstacle in todayâ€&#x;s economy. $10,000 for window improvements might be a heavy burden especially for a low- and medium- house income. There are alternative pathways to finance your improvement. Many manufacturers offer lease and lease-purchase agreements. Leasing an energy efficient product can significantly reduce the upfront cost. There are also many energy performance contracts, where a contractor can install and maintain your new windows in addition to providing you with the upfront cost. An energy performance contractor (EPC) guarantees you a specific amount of savings every year and in return they are paid from the energy saving cost during the contract period, which usually lasts for about 10-15 years. For more information about EPC visit www.energyservicescoalition.org. In conclusion, depending on orientation, area, and characteristic, windows can account for 10-30% or more of a code-compliant home's heating energy load. Besides, if windows are designed and used appropriately they can also play a role in lighting and ventilation. For all these explanations, windows have a great consequence on the energy efficiency and environmental impact of your house.
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Passive Systems: Now that we have seen a variety of methods to enclose the thermal envelope, we are now going to propose “tier 2” of the energy efficiency pyramid, passive systems for heating, cooling, and lighting. The purpose of these systems are to aid the “plug filling” thermal envelope methods by optimizing the microclimate depending on the season, sun angle, prevailing winds, precipitation, and any other microclimate advantages. The passive system that will be described in this section is “Landscaping for energy efficiency.” In this section we will explicitly describe reasons for placement of plants and other landscape items on or around the home as they relate to heating, cooling, and lighting and the quality of the microclimate that each provides. Much like the thermal envelope solutions, we will discuss in terms of energy savings and return-oninvestment.
Landscaping for Energy Efficiency: The New York City metropolitan area is well within the temperate climate zone (Figure 16) experiencing four distinct seasons. Selection and placement of landscape plants are critical to this exercise in taking advantage and avoiding what these seasons have to offer. Ultimately in the summer months we want to optimize the prevailing winds to allow for natural ventilation and cooling and shade the sun to avoid passive solar heat in order to reduce air conditioning usage, lowering your electric bill. Alternatively, in the winter months, one wants to block cold winds and optimize sunlight for solar hear gain in order to lower your heating bill. Theoretically, in all seasons we want to optimize light, which may be difficult in the summer months without solar heat gain. Evapotranspiration is another microclimate element we want to optimize to aid in cooling during the summer months. Page 23 of 47
Figure 16: Climate zones of the United States, courtesy DOE
Winter: Winter in New York City and the northern United States in general can be rather harsh. Temperatures can go as low as -20 to -10 degrees Fahrenheit (Lechner, 09). When adding the wind chill factor, temperatures can feel as low as -50 degrees Fahrenheit (Wheeling Jesuit University, 2004). These winds tend to come from the Northwest during the winter months, typically about half of the year (NYS Climate Office, 2011). Optimal placement of evergreen trees and shrubs a short distance from the north to north west façade of your home can potentially eliminate the wind chill factor as it relates to home heating. As seen in figure 17, a small amount of wind reduction can have a huge effect on infiltration heat loss. In fact, cold air infiltration in the Northeast is responsible for 1/3 winter heat loss in the average home and up to ½ on windy days (Lechner, 09).
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Figure 17: Reduction in heat loss from reduction in wind, courtesy DOE
When placing evergreen trees and shrubs, it is important to follow some simple guidelines in order to appropriately direct the wind away from your home. The evergreen mass should be a dense thicket of trees and shrubs in order to achieve the appropriate heights, widths, and porosity of the planting. The windbreak should be placed away from your home approximately two to five times the mature height of the evergreen trees (DOE, 1995). This will give your home optimal wind protection by pushing it up and over your home (Figure 18). This distance will also allow the wind that does make it through the windbreak to dissipate by the time it reaches the façade. Placing too far away may allow the wind that is intended to get pushed over the home to dip back down into the façade you‟re trying to avoid (Figure 19). Try to make the windbreak as continuous as possible with low-lying branches that reach the ground. Gaps in windbreaks may result in an opposite effect increasing wind velocity. This is a method that we will want to optimize in the summer, but definitely not in the winter (Figure 20). The addition of a temporary trellis with evergreen vines may temporarily fill those gaps until the larger trees grow enough to appropriately infill the gaps. The windbreak width should also be at least ten times the height to optimize the wind shadow for the northern façade of your home. Page 25 of 47
Figure 18: Windbreaks push wind over the home, courtesy DOE
Figure 19: Distance as a function of height of windbreak, courtesy Harris
Figure 20: Gaps in a windbreak actually increase wind velocity, courtesy Lechner
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When selecting species of evergreens to plant, you typically want to choose fast growing, pest resistant trees and shrubs. You want fast-growing species to optimize the windbreak capabilities and pest resistant to avoid attracting pests to your home. Table 9 shows a list of evergreen tree, shrub, and vine species that may be used for the purposes of a windbreak. Table 8 : Evergreen plant suitable as windbreaks
Latin Name Picea abies Pinus resinosa
Common Name Norway Spruce Red Pine
Growth Rate Med to Fast Med to Fast
Pest Resistance High Med
Mature Height 40 to 60‟ 50 to 100‟
Juniperus virginiana
Eastern Red Cedar Green Giant Arborvitae Radicans Cryptomeria
Slow to Med
High
60‟
Fast
High
50 to 60‟
Fast
High
30 to 40‟
Black Hills Spruce American Holly
Med
High
30 to 60‟
Slow
High
30‟
Taxus cuspidata
Japanese Yew
Slow
High
8 to 10‟
Hendera helix
English Ivy
Fast
Very High
N/A
Lonicera sempervirens
Coral Honeysuckle
Fast
High
N/A
Thuja standishii X plicata „Green Giant‟ Cryptomeria japonica var. sinensis „Radiacans‟ Picea glauca var. densata Ilex opaca
Now that we‟ve discussed blocking the prevailing northwesterly winds with an appropriate windbreak planting, it is equally important to optimize the winter sun angle along the south façade of your home. Hopefully your neighbor‟s house, fence, or trees are not impeding upon this angle. The “solar access boundary” is a conical surface showing the sunlight access to a building or specific site on December 21 from 9 AM to 3 PM (Figure 21). If any buildings, trees, fences, etc. protrude through this boundary, the building you are trying to optimize for Page 27 of 47
winter sunlight will have a shadow cast upon it. Table 10 and Figure 22 reveal how tall an object can be related to the sun angle. For example, when looking at Table 10, New York is approximately at latitude 40, which, when transferring the data to Figure 22, means that the tallest tree at mature height at point L that could be planted is 10‟ and cannot be planted any closer than 20‟ so as not to block the winter solstice sun at 12:00 noon. At 3:00 PM, the tallest tree at point B could be 10‟ but has to be planted at least 47 feet away. Perhaps a nice flowering shrub is more appropriate for this location with small trees further to the south where height is not as much of an issue. A flowering tree such as Cercis Canadensis that never grows above 20‟ may be appropriate for points D or N (Lechner, 2009).
Figure 21: Solar Access Boundary, courtesy Lechner
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Figure 22: Maximum height objects can reach as they relate to the Solar Access Boundary, courtesy Lechner Table 9: Distance in feet from building, courtesy Lechner
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If existing mature trees already exist within the “solar access boundary,” you may want to consider pruning the lower limbs to allow the winter sun to protrude beneath the main crown of the tree, which will be of considerable benefit in the summer when the dense foliage blocks the hot summer sun (Figure 23). Keep in mind that the distances and heights given on Table 10 and Figure 22 assume that the lot is flat. If the land slopes uphill from home from the south façade, you will need to subtract that difference in elevation from these heights. Alternatively, if the land slopes downhill, you can plant taller species.
Figure 23: Prune lower branches on south facade to allow for winter sun, courtesy Lechner
In New York State, the average home consumes approximately 76,000 cubic feet of natural gas each year for home heating (EIA, 2011). Assuming that all of it is consumed in the six month period from mid-October to mid-April, 12,667 cubic feet of natural gas is consumed each month. Studies have found that 25 percent of home heating costs can be reduced by planting suitable windbreaks. Later on we will discuss the cost savings associated with this reduction, but it can feel rewarding to offset 3,167 cubic feet of natural gas consumption, while beautifying your lot at the same time. Page 30 of 47
Summer: As mentioned earlier, during the summer months in the New York City metropolitan area, southwesterly winds are to be optimized for cooling while sunlight is shaded to avoid passive solar heat. Evapotranspiration may also be optimized for a cooling effect. In the United States, air conditioning usage accounts for 16% of all residential electric energy use (EIA, 2011). In New York State 7.8% of all residential electric energy use is from air conditioning (EIA, 2011). Of the households in New York State that do have air conditioning, their air conditioning consumption is 26 percent of their total, which is actually 52 percent considering air conditioning is only used for half the year in a temperate climate. That accounts for approximately 1,552 KWhs per household per year based on 4.7 million households (EIA, 2011). When these units are shaded and the southern façade is optimized for shade, air-conditioning consumption can be reduced anywhere from 15 to 50% (MSU Extension, 2001). In fact, shading an air conditioning unit alone can increase its efficiency by 10% (DOE, 2011). When placing trees for shading purposes it is important to follow simple guidelines in order to optimize shading while at the same time, maintain the winter sun angle. As mentioned earlier, if tall deciduous trees exist along your southern façade, it is important to prune the limbs so as to not interfere with the “solar access boundary” between 9 AM and 3 PM, which is when 80% of solar radiation is gained in the winter months (Lechner, 2009). Consult a licensed arborist to perform this task. An incorrect prune on the wrong limb could be detrimental to the mature tree. Also, refer to Figure 24, the winter tree shadow template, to get a general idea of how your mature tree will shade your home. For example, in New York, a tree that is directly southeast from your home will cast a shadow on it up to five times the height of the tree and
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about half that much during the summer months. Trees tend to be superior to shading than manmade structures due to the fact that they do not absorb and radiate heat (Figure 25).
Figure 24: Winter tree shadow template, courtesy Lechner
Figure 25: Shading from trees vs. man-made structures, courtesy Lechner
If you desire to plant a deciduous tree along the southern faรงade, keep in mind, it may take several years before you reap the energy saving benefits from shading. In fact, you may be doing the reverse considering that even without leaves; deciduous trees block 30 to 60% of winter sunlight. Some species, such as oaks, tend to hold onto their leaves well into the winter months further blocking much need winter sun. Select a fast growing, oval to round shaped, and Page 32 of 47
high branched tree. Red Maples (Acer rubrum) and London Plane Trees (Platanus X acerifolia) would be a good choice. Perhaps a trellis with a deciduous climbing vine such as Parthenocecis quinquifolia can provide the much needed shading to conserve air-conditioning consumption as an alternative to plating a tree. Vines also release water vapor through evapotranspiration from the leaves creating a cooling effect. Smaller trees with crowns lower to the ground may be desired along the western façade for late afternoon shading when it‟s the warmest. These trees don‟t interfere with the winter sun angle and greatly aid in summer cooling. Optimizing the prevailing southwesterly winds during the summer in New York is equally as important as shading. As discussed earlier in the “Winter” section, wind velocity is greatly increased between gaps and at the end of windbreaks. One way to increase wind speed is to either funnel the wind via shrubs toward your home or plant trees with high canopies to allow for cool summer breezes to flow underneath (Figures 26 and 27). Planting flowing trees in this location can have the additional benefit of the wind transporting the fragrant aromas you‟re your home. Shrubs may also be sited off of the western façade to optimize the wind (Figure 28). If your home has a roof vent, the southwest winds will enter your home at ground level and push warmer air through the roof cooling the home.
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Figure 26: Summer breezes are funneled toward the home via shrubs, courtesy Sustainable Energy Authority Victoria
Figure 27: Summer breezes are funneled under high canopy trees, courtesy Lechner
Figure 28: Placement of shrubs can deflect wind toward your home, courtesy Lechner
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All Seasons: As mentioned earlier, natural light is to be optimized year round in order to aid in reducing your monthly bills and energy consumption. In New York State, lighting accounts for 15.7 percent of electricity usage in the average household, which is approximately 940 KWh per year based on 7.1 million households (EIA, 2011). The obvious way to accomplish this is to install large windows and skylights along the south facade of your home. A less obvious method is to position plantings, trellises, and reflective pavements in order to optimize interior light. In order to optimize this light in the winter, be sure to obviate obstructions and avoid planting within the “Solar Access Boundary.� The low sun angle during the winter months will allow ample light to penetrate your home. During the summer months, shading is to be optimized while optimizing light. This can be rather tricky. One way to accomplish this goal is with reflected light. As seen in Figure 29, light reflected off of the ground actually penetrate further into your home than direct sunlight in the summer without gaining too much solar heat gain. A light colored pavement will improve this reflectivity. The addition of a trellis with a deciduous vine will also aid in cooling your home while optimizing this reflectivity.
Figure 29: reflected light penetrates deeper into your home than direct sunlight, courtesy Lechner
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Plants also improve the quality of light that enters your home by reducing glare. A tree with a light to moderate foliage such as Gleditsia triacanthos var. inermis, the Common Thornless Honeylocust, is a good example of one of these trees. One vernacular architectural example that optimizes light and temperature with the methods described above is the Pennsylvania Bank Barn (Figure 30). This barn was introduced to Pennsylvania in the 19th century by German immigrants for cattle grazing. With this design, the cattle that reside in the basement benefit from the solar heat gain and light in the winter while benefiting from the shade and reflected light in the summer. Today this concept can be obtained by proper placement of trees and trellises.
Figure 30: Pennsylvania Bank Barn
Cost Analysis: Now that we have discussed the techniques and benefits of landscaping for energy efficiency, itâ€&#x;s time to design your landscape and evaluate your associated costs to come up with your return-on-investment. First letâ€&#x;s come up with a landscape design that optimizes energy efficiency for the New York metropolitan area (Figure 31). In this design, we are optimizing for winter conditions by planting evergreen trees, shrubs, and trellises with evergreen vines off of the north facade of the home. We are also going to bring in a tree pruning company to spend a
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day pruning the lower branches off of the two existing trees along the southern facade. This will allow us to optimize the “Solar Access Boundary� during the winter while providing shade in the summer. Also, for the summer, we are going to plant high canopy flowering trees and a few shrubs along the eastern and western facades to allow for breezes. We are also going to construct a trellis along the southern facade, which will hold a deciduous vine to allow for shading and reflective light. These costs are listed in Table 11.
Figure 31: Landscape design that optimizes energy efficiency for New York City Metropolitan Area
Page 37 of 47
Table 10: Landscape improvement costs
Item Quantity Supply Picea abies (8-10‟) 3 $300 EA Juniperus virginiana 2 $250 EA (8-10‟) Illex opaca (6-7‟) 2 $250 EA Cornus florida (35 $250 EA 3.5” caliper) Magnolia virginiana 5 $250 EA glauca (10-12‟) Hydrangea 5 $65 EA quercifolia (3-4‟) Lonicera 24 $1.50 EA sempervirens Clematis (1 Gallon) 8 $30 EA Free standing trellis 3 $169 EA Porch trellis 1 $1,086.71 Tree pruning 1 Total * Prices courtesy Home & Garden Kraft, Inc.
Installation $155 EA $124 EA
Total $1,365.00 * $748.00 *
$370 EA $375 EA
$1,240.00 * $3,125.00 *
$420 EA
$3,350.00 *
$80 EA
$725.00 *
$0.35 EA
$44.40 *
$10 EA $0 $1,742.40
$320.00 * $507.00 ** $2,829.11 **,^ $1,200.00 *** $15,453.51
** Prices courtesy Home Depot *** Prices courtesy Almstead Tree Service ^ Porch trellis based on materials (dimensional lumber, stain, fasteners, concrete, NYC sales tax; installation at $30/Hr/Laborer, 3 person crew for 2 days, plus 21% overhead and profit
As discussed earlier, natural gas consumption in the winter and electricity consumption in the summer can be drastically reduced with landscaping techniques. The winter gas bill can be reduced 25 percent in the winter, while air conditioning costs can be reduced 15 to 50 percent in the summer. The electricity bill can also be reduced somewhat year round from reduced lighting costs. For the purposes of this scenario, let‟s assume we save 25 percent monthly on air conditioning for six months out of the year and 25 percent year round on lighting. Table 12 summarizes the cost and energy savings for a typical New York resident (EIA, 2011; Cenhud, 2011). Page 38 of 47
Table 11: Cost and energy saving scenario for a typical New York household
Service
Consumption Avg. Reduction / mo. monthly bill 12,667 CF $246 25%
Total Months
Energy saved / Month
Cost savings / Month
Natural 6 3,167 CF $61.50 Gas Electricity 500 KWh $96.48 Elect A/C 260 KWh $50.17 25% 6 65 KWh $12.54 Elect 78.5 KWh $15.15 25% 12 19.63 KWh $3.79 Lighting As shown in Graph 2, assuming the owner took out a loan at 5% interest, the return-oninvestment for this landscape improvement is 35 years 8 months.
Graph 2: Return-on-investment for supply and installation of landscape design
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This length of time may not give the homeowner an incentive to make this investment, especially since the payback time is longer than a typical 30 year mortgage. This, in this author‟s opinion, is due to high installation costs in the New York City region. In the above estimate, $30/hour was assumed, which is actually less than prevailing wage as indicated by the labor laws for public work. Since this is residential work, approximately half of the prevailing wage cost of $65/hour for a union laborer was assumed, which is still drastically higher than other cities in the United States. As a homeowner looking to save on energy costs, you may elect to reduce this return-on-investment by either choosing a simpler, less expensive design, or elect to perform the work yourself. The below cost estimate and graph assume only material costs for the same design with the exception of tree pruning which should be done by a licensed arborist. The return-oninvestment as seen in table 13 and graph 3 is now 15 years, which gives a much better energy conservation incentive. Table 12: Return-on-investment for supply of landscape design materials
Item Picea abies (8-10‟) Juniperus virginiana (810‟) Illex opaca (6-7‟) Cornus florida (3-3.5” caliper) Magnolia virginiana glauca (10-12‟) Hydrangea quercifolia (34‟) Lonicera sempervirens
Quantity 3 2
Supply $300 EA $250 EA
Total $900.00 * $500.00 *
2 5
$250 EA $250 EA
$500.00 * $1,250.00 *
5
$250 EA
$1,250.00 *
5
$65 EA
$325.00 *
24
$1.50 EA
$36.00 *
Clematis (1 Gallon) Free standing trellis
8 3
$30 EA $169 EA
$240.00 * $507.00 ** Page 40 of 47
Porch trellis 1 $1,086.71 Tree pruning 1 Total * Prices courtesy Home & Garden Kraft, Inc.
$1,086.71 **,^ $1,200.00 *** $6,894.71
** Prices courtesy Home Depot, Inc. *** Prices courtesy Almstead Tree & Shrub Care Co. ^ Porch trellis based on materials (dimensional lumber, stain, fasteners, concrete, NYC sales tax)
Graph 3: Return-on-investment, supply costs only
Market Incentives: Throughout this manual, we have introduced various methods for energy conservation and return-on-investment via sealing the thermal envelope and introducing the passive system of landscaping for energy efficiency. Tax incentives and other market tools may help us achieve a
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sooner return-on-investment, which gives an incentive for energy efficiency as well as spark the local sales market for energy efficient products. The federal government introduced the “Tax Incentive Assistance Project (TIAP) back in 2009, which granted a tax credit for 30% of qualifying energy efficient products for the thermal envelope of existing and new homes with a cap of $1,500.00. If this incentive was applicable to landscape design products ( i.e. trees, shrubs, trellises, etc.), the above return-on-investment would be reduced to 12 years 6 months. Perhaps it may be more cost effective to purchase portions of your landscape design incrementally in order to qualify for the tax credit each year. This may also obviate the need to take out a loan, thus saving even more in the long run. New York State also provides certain incentives at getenergysmart.org.
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References: "Cost of Low-E Glass (ie: per Square Foot) - Windows Forum - GardenWeb." That Home Site! Forums - GardenWeb. Web. 26 May 2011. <http://ths.gardenweb.com/forums/load/windows/msg0210501621850.html?6>. "Energy Tax Credit 2011 â&#x20AC;&#x201C; Not What It Used to Be." Darwin's Money â&#x20AC;&#x201D; Financial Evolution for the Masses. Web. 26 May 2011. <http://www.darwinsmoney.com/energy-tax-credit-2011/>. Heating & Cooling Degree Days - Free Worldwide Data Calculation. Web. 26 May 2011. <http://www.degreedays.net/>. "How to Select Windows for Energy Efficiency and Style - a Knol by Daniel Snyder." Knol - a Unit of Knowledge: Share What You Know, Publish Your Expertise. Web. 26 May 2011. <http://knol.google.com/k/daniel-snyder/how-to-select-windows-for-energy/19yp2ug8iz123/72>. "Push Out French Casement - Marvin Windows and Doors." Marvin Windows and Doors Marvin Windows and Doors. Web. 26 May 2011. <http://www.marvin.com/windows/frenchpush-out-casement-windows/sizes-performance-and-specs/>. "Understanding Energy-Efficient Windows - Fine Homebuilding Article." Fine Homebuilding: Get Expert Home Construction Tips, Tool Reviews, Remodeling Design and Layout Ideas, House Project Plans, and Advice for Homeowners. Web. 26 May 2011. <http://www.finehomebuilding.com/how-to/articles/understanding-energy-efficientwindows.aspx>.
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"Watts (W) to BTU/hr Conversion Calculator - RapidTables.com." Online Reference & Tools RapidTables.com. Web. 26 May 2011. <http://www.rapidtables.com/convert/power/Watt_to_BTU.htm>. Welcome to the Efficient Windows Collaborative Web Site. Web. 26 May 2011. <http://www.efficientwindows.org/>. Lechner, Norbert. Heating, Cooling, Lighting: Sustainable Design Methods for Architects. New York: John Wiley & Sons, Inc, 2009, 295-341. Harris, Charles W. and Nicholas T. Dines. Time-Saver Standards for Landscape Architecture: Second Edition. New York: McGraw-Hill, 1998. Tuckahoe Nurseries, Inc., 2010-2011 Catalogue, Tuckahoe, NJ 2010. Wettstien, Chris E. (Owner of Home & Garden Kraft, Milford, N.J.) Interview by author. Inperson interview of this local landscape contractor with cost estimate. Milford, N.J., May 16, 2011. Almstead, Ken. (CEO of Almstead Tree and Shrub Care Company) Interview by author. Telephone interview of this local tree care specialist with cost estimate. New York, NY, May 16, 2011. Department of Energy. “Landscaping for Energy Efficiency.” April 1995. http://www.nrel.gov/docs/legosti/old/16632.pdf Homer TLC Inc. “The Home Depot: Shop all Departments.” Accessed May 19, 2011. http://www.homedepot.com/?cm_mmc=SEM|RPM|ST_Branded|GGL_2881&skwcid=TC|13614| home%20depot||S|e|6468551964 Page 44 of 47
Michigan State University Extension. “Energy Facts: Landscaping for Energy Conservation – Benefits and Important Considerations.” July 20, 2001. http://web1.msue.msu.edu/msue/iac/energy/conservation-landscape_benefits.pdf U.S. Energy Information Administration. “New York Household Electricity Report – Table.” January 30, 2006. www.eia.doe.gov/emeu/reps/enduse/er01_ny_tab1.html Central Hudson Gas & Electricity Corporation. “New York State Typical Bill: American Gas Association Survey.” June 30, 2010. www.cenhud.com/rates/res_gas.html Sustainable Energy Authority – Victoria. “Sustainable Energy Info – Landscape Design.” Accessed May 14, 2011. http://www.sustainability.vic.gov.au/resources/documents/Landscape_design.pdf Central Hudson Gas & Electricity Corporation. “New York State Typical Bill: Edison Electric Institute Bill Survey Residential. July 1, 2010. www.cenhud.com/rates/res_elect.html New York State Climate Office. “The Climate of New York.” Accessed May 14, 2011. www.nysc.cas.cornell.edu/climate_of_ny.html Energy Information Administration. “Regional Energy Profiles: U.S. Household Electricity Report.” July 14, 2005. www.eia.doe.gov/emeu/reps/enduse/er01_us_figs.html#1 Energy Information Administration. “Natural Gas Consumption and Expenditures in U.S. Households by End Uses and Census Region, 2001.” 2001. www.eia.gov/emeu/recs/byfuels/2001/byfuel_ng.pdf Bankrate, Inc. “Loan Calculator and Amortization.” Accessed May 19, 2011. http://www.bankrate.com/calculators/mortgages/loan-calculator.aspx Page 45 of 47
Tax Incentives Assistance Project (TIAP). “General Information.” Accessed May 19, 2011. http://energytaxincentives.org/general/incentives.php New York State Energy Research and Development. “Home page.” Accessed May 19, 2011. http://www.getenergysmart.org/ Wheeling Jesuit University. “Temperature Team Graph 3 – New York CIty.” 2004. http://www.e-missions.net/weather2/pdf/tempgraph3.pdf
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I
South Area Supply/SF Supply Installation total cost/Window # of windows Total cost
20 50 1000 200 1200 4 4800
Initial investment
10980
East
West 20 38 760 175 935 2 1870
North 20 38 760 175 935 2 1870
20 23 460 150 610 4 2440
New SHGC Building Characteristics Faรงade Glass Area SHGC (sf) North 30 0.36 East 10 0.56 West 10 0.56 South 40 0.22 Roof
old SHGC 0.75
Monthly Solar Radiation Values, New York City (kBtu/sf) Faรงade Jan Feb Mar Apr May Jun Jul Aug Sep Oct 4 10 13 30 18
6 15 15 29 23
9 22 23 33 36
10 27 25 29 44
15 32 30 27 55
15 31 30 24 56
16 35 32 27 58
7 19 20 34 31
5 11 12 25 18
4 9 10 23 15
at Gains (kBtu) Faรงade
Jan
Feb
Mar
Apr
May
Jun
Jul Aug Sep Oct
Nov
Dec
48 59 71 262
65 85 82 257
99 122 126 287
110 149 140 257
161 179 170 237
164 176 170 215
175 195 179 234
55 64 66 220
48 50 53 204
134 174 153 265
9 25 23 33 40
Dec
North East West South Horizontal
North East West South Horizontal
12 31 27 30 51
Nov
96 79 142 105 131 112 290 301
total heat gain 440 Kbtu/hr Winter gain 3,575 Summer Gain 3,641
489
635 Kwatt 1048 1067
656
748 Saving 231 235
725 783 725 659 597
405
355
window area HDD CDD $/Kwatt 20 4227 1712 0.22
Winter
South Difference in U-Value 0.25 Area 20 HDD 4227 Btu/day 21135 Btu/hr 507240 Number of window 4 Btu/ hr 2028960 Kwatt 594.654 Total Saving 130.824
East 0.18 20 4227 15217.2 365213 2 730426 214.075 47.0966
West 0.18 20 4227 15217.2 365213 2 730426 214.075 47.0966
North
East 0.18 20 1712 6163.2 147917 2 295834 86.7039 19.0749
West 0.18 20 1712 6163.2 147917 2 295834 86.7039 19.0749
North
0.1 20 4227 8454 202896 3 608688 178.396 39.2472
Summer
South Difference in U-Value 0.25 Area 20 CDD 1712 Btu/day 8560 Btu/hr 205440 Number of window 4 Btu/ hr 821760 K Watt 240.844 Total Saving 52.9857
0.1 20 1712 3424 82176 3 246528 72.2532 15.8957
$/Kwatt - gas 0.125
Winter Non-Sloar saving 264.264309 Winter Solar Saving 230.500636 Total Winter Saving 494.764946
Summer Non-Sloar saving 107.031109
Total Saving 601.796055
Inistial investment Total saving Tax credit Gas bill Electricity Total current bill total new bill
year new cost
1 4740
2 9480
3 14220
4 18960
5 23700
6 28440
7 33180
8 9 37920 42660
10 47400
11 52140
12 56880
13 61620
1 2 3 4 5 6 7 8 9 10 11 12 13 14918.2 19056.41 23194.61 27332.82 31471.02 35609.22 39747.43 43885.63 48024 52162.04 56300.24 60438.45 64576.65 180000 160000 140000 120000 100000 Consumption
year cost
10980 601.7961 $/year 200 1800 $/year 2940 $/year 4740 $/year 4138.204 $/year
80000 60000 40000 20000 0 0
5
10
15 Years
20
25
30 35 40 Consumption withouthâ&#x20AC;Ś
14 66360
15 71100
16 75840
17 80580
18 85320
19 90060
20 94800
21 99540
22 104280
23 109020
24 113760
25 118500
26 123240
27 127980
14 15 16 17 18 19 20 21 22 23 24 25 26 27 68714.86 72853.06 76991.26 81129.47 85267.67 89405.87 93544.08 97682.28 101820.5 105958.7 110096.9 114235.1 118373.3 122511.5
Years 0 1 Without landscape improvements $0.00 $2,633.76 With landscape improvements $10,632.00 $12,776.04
2 3 4 5 6 7 8 $5,267.52 $7,901.28 $10,535.04 $13,168.80 $15,802.56 $18,436.32 $21,070.08 $14,920.08 $17,064.12 $19,208.16 $21,352.20 $23,496.24 $25,640.28 $27,784.32
9 $23,703.84 $29,928.36
10 $26,337.60 $32,072.40
11 $28,971.36 $34,216.44
12 $31,605.12 $36,360.48
13 $34,238.88 $38,504.52
$70,000.00
$60,000.00
$50,000.00
$40,000.00
$30,000.00
$20,000.00
$10,000.00
$0.00
Years Years
Without landscape improvements
With landscape improvements
14 $36,872.64 $40,648.56
15 $39,506.40 $42,792.60
16 $42,140.16 $44,936.64
17 $44,773.92 $47,080.68
Years Without landscape improvements With landscape improvements
0 $0.00 $7,806.60
1 $2,633.76 $9,950.64
2 3 4 5 6 7 8 $5,267.52 $7,901.28 $10,535.04 $13,168.80 $15,802.56 $18,436.32 $21,070.08 $12,094.68 $14,238.72 $16,382.76 $18,526.80 $20,670.84 $22,814.88 $24,958.92
9 $23,703.84 $27,102.96
10 $26,337.60 $29,247.00
11 $28,971.36 $31,391.04
$80,000.00
$70,000.00
$60,000.00
$50,000.00
Years $40,000.00
Without landscape improvements With landscape improvements
$30,000.00
$20,000.00
$10,000.00
$0.00 1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
12 $31,605.12 $33,535.08