| SHCS Calculator SHCS Calculator | | | |
| Basic Instructions: If you want to use your own SHCS Calculator for sharing or editing later, you must register as a user. Then you can save a copy of this sheet for your own use. First and foremost, be sure to CLEAR any bold faced entries in the cells that don't apply to you (don't delete the cell contents! - select the cell to clear, then go to the "cells" menu and select "clear cells".) THEN follow these STEPS - STEP ONE - FILL IN THE YELLOW DATA CELLS - Calculate the Greenhouse Volume. We use this section to calculate the total air volume of the greenhouse. If you know it already, there is a place to insert it. STEP TWO - FILL IN THE GREEN DATA CELLS. STEP THREE - Read your results in the blue cells. Enjoy! | | |
| First, we calculate the volume of air in the greenhouse - fill in these YELLOW DATA cells in the Greenhouse Dimensions yellow section below | | |
| Select the number and size of the FANS to use to move all that air underground 5 times per hour - Play around with the GREEN DATA CELLS to get close to the desired outcome in the BLUE CELLS "Exchanger Rate" and "Tubing Air Speed". Let's get started. And don't forget, if you register as a Numsum user, you can save a copy of the SHCS Calculator for your personal use and that you can share. I would be happy to look at your numbers and make suggestions based on your figures. Join up and create a copy for others to see! | | |
| NOTE: Remember - your important Calculated figures are in cells this color for the entire sheet | | | |
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| DIRECT YOUR QUESTIONS SPECIFIC TO THIS SHEET'S TERMS AND METHODS TO THE SHCS FORUM. Ask any questions you have and get answers from me directly and from the rest of the community of solar greenhouse builders interested in the possibilities and opportunities - listen in and respond. | | |
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| STEP ONE - Calculate the Greenhouse Volume from its Dimensions STEP ONE - Calculate the Greenhouse Volume from its Dimensions | The greenhouse "BOX" sections refers to the space that is defined by the straight up walls - the volume from the floor just to the top of the walls. Then you calculate and add in the volume of the roof section above the BOX sections, usually hoops... Use the Hoop Section's calculator if you have a hoop style curved roof (see NB#2 below). NB#1: a half circle hoop house has an 180 degree included arc. NB#2: This Hoop Section calculator applies only if the Diameter of the hoop's curve is the same as the width of the greenhouse. PS - it usually isn't! NB#3: If NB#2 does not apply, use this sheet to get a figure to use in CELL J18. NB#4: If you have a gabled or shed roof, you can just measure the height from the top of the walls to the top of the peak - fill in the respective Length and Width that apply and you will have the volume of your shed or gabled roof section to include in the Total Greenhouse Volume. |
| Box Sections Box Sections | Height | Length | Width | Section Sub total CUFT Section Sub total CUFT | Hoop Sections | Arc Included | Width | Length | Hoop Section Sub Total CUFT |
| Main | 6.1 | 42 | 20 | 5124 | Main | 0 | 0 | 0 | |
| Section2 | 0 | 0 | 0 | | Section2 | | | | |
| Section3 | 0 | 0 | 0 | 0 | Section3 | | | | |
| Shed and Gable Roof Sections | Height above Box Section Wall | Length | Width | | | | | | |
| Main | 6 | 42 | 20 | 2562 | | | | | |
| Section2 | 0 | 0 | 0 | | | | | | |
| Section3 | 0 | 0 | 0 | | | | | | |
| Total Square footage > | 840 | Design should be 1.33 feet of tubing per square foot of floor > | 1117.2 | | You can get more precise figures for your Hoop Section Volumes from here. Remember to zero out or clear the contents of calculator cells above if you use that other calculator - place the figure you get in the next cell over (just above the calculated value for "Total Hoop Volume CU/ft" - it should be blank before you add the figure from the other calculator) | |
| Total GH Air Volume > | 7686 | | Total Section CUFT > | 7686 | | | | Total Hoop Section CU/FT | |
| If the calculator volume fails to work for your unique design, just enter your own total volume here (Cell B20) > | | For every sq/ft of floor there is this many cu/ft of air : >> | 9.15 | Total wall area for Box and Shed Sections | 1008.4 | Total roof area for Box and Shed Sections (approximate!) | 1201.2 1201.2 | For every sq/ft of floor there is this much sq/ft of exposed wall and roof in the Box and Shed Sections (approximate!) >> | 2.63047619047619 2.63 |
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| Now you decide how many and how big the FANS are going to be to move all the air in the greenhouse underground 5 times per hour when the sun is shining. Play with the Number of Fans in A26 and watch the BLUE cells C26 and H30. Ideal Design Numbers should be: 5 air exchanges per hour (filled in for you) and in cell H30, 2-4 feet per sec air speed in the Underground Air Circulation Tubing. Play around with the Number of Fans and the Fan CFM in cell D26 to get close to that outcome. | Don't change the italized Formula Cells!!! | | |
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| STEP TWO Fans | Enter the number of fans you think might work. start with one per 2000 square foot of floor space (refer to the Floor Space figured for you in cell B14) . THEN, using the calculated CFM in cell C21, choose the CFM rating for the fan you have in mind or on hand (if you have the manufacturer's data sheet, use the CFM rating for 0.1" or 0.2" backpressure) Play around with the entries until you get close to or a little more than 5 air exchanges per hour in cell E25. | | |
| Number of Fans | Exchange Rate TIMES/HOUR Design | Fan CFM Calculated | Fan CFM from Manufacturer List | Exchange Rate TIMES/HOUR Calculated | | | | | |
| 2 | 5 | 320.25 320.25 | 320.25 | 5 5.00 | | | | | |
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| STEP THREE - Underground Air Circulation Tubing STEP THREE - Underground Air Circulation Tubing | B29/30 and C29/30 are standard for a 4" tubing system. Enter the tubing length - anything between 30 and 70 and the enter the number of tubes you want each fan to handle. Tubing Layout Designs are discussed here and here. Then play around, watching the blue cells change... you want the "Tubing Air Speed" to show about 2 to 4 feet per second (smaller numbers are better) | |
| Number of Plenums (same as number of Fans) | Tubing Diameter | Effective Diameter | Average Length of tubing | # of tubes in each plenum | Total Tubing Effective Area SQFT | Total Feet of Tubing | Tubing Air Speed FT/SEC | Time in each Tube in SEC | |
| 2 | 4 | 3.75 | 18 | 36 | 5.51953125 5.51 | 1296 1,296.00 | 1.9340410474168437 1.93 | 9.30693793911007 9.30 | |
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| STEP FOUR - Cost of system hardware | Enter the values that apply in the green cells | | |
| Per foot cost of your tubing in dollars (add $0.20 per foot if you need tubing with a sock soil filter) | Total Tubing Cost | Cost of each Fan Plenum package (change to reflect your fan costs - plenums are $10-$15) | Total Fan and Plenum cost | Controls Package (only one required per greenhouse system) | Total Hardware Costs | | | | |
| .25 $0.25 | 324 $324.00 | 100 $100.00 | 200 $200.00 | 100 $100.00 | 624 $624.00 | | | | |
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| STEP Five - Payback Calculations | Enter the correct rates for your situation in the green data cells. Enter the # of days you expect to get a 1 F deg Rise in the soil temperature. In Colorado, we get at least 180 days per year of full sunny gain sufficient to raise our soil mass temperature one degree in a day. Your zone can be derated using Colorado as your reference. Florida is about the same, the NE and NW may be as low as 100, the Mid States could be around 150. I'd like to put a calculated number here based on your Degree Day and Solar Exposure data, but that will have to be managed later... for now, we are stuck with a WAG solution (wild ass guess (:-) If you know an UNVENTED greenhouse in your area can get to 90 deg F for any one day, guess how many full days that might happen - that's the figure we are after. | |
| Mass of heatsink in pounds with soil mass at 80 lbs per cubic foot | 201600 | Heat stored with a 1 F deg rise in soil temp | 201600 | Your Therm cost ($ per 100,000 BTU's) go here for rates | 1.55 $1.55 | Stored heat value as natural gas cost per 1 F deg rise | 3.1248 $3.12 | # of days you expect get a 1 F deg Rise in the soil temperature. | 180 |
| Gas Value gained each year | 562.464 $562.46 | Your Electricity Cost in $/kilowatt hour (rates here) | 0.08 $0.08 | Annual Fan Operating cost (enter data below) | 55.29599999999999 $55.30 | Yearly Net | 507.16800000000006 $507.17 | Hardware Payback in Years | 1.2303615370054892 |
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| Fan Power Calculation | Volts | Amps | Wattage | Daily Hours | Number of fans (from A26) Number of fans (from A26) | | | | |
| Volts | 120 | 2 | 240 | 8 | 2 | | | | |
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