LEED Certification: Gold

Rating Achieved: Gold
Home Size Adjustment: -8
Number of points: 67
Total Cost: $8,360.13 (Rough estimate, not including tax or shipping)

Biggest point contributions:

(1) Sustainable Site -Taking steps to minimize the constructions impact on the site gained 18 points.  This includes planting non-invasive plants, installing a light colored, high albedo permeable driveway, and having a compact development.

(2) Location and Linkage - Choosing the right site gained a lot of LEED points for little cost.  The site had to be on previously developed land, near a water line, near community resources, and near but not on to of a park.  By assuming the house was built on this kind of site, the project gained approximately 11 virtually free points.

(3) Reduced Water Need - Drought tolerant plants (ground cover - carpobrutus edulis), low flow rate toilet and shower, and reduced irrigation need accounted for 12 points.

(4) Environmental Quality - Reducing exposure to pollutants by not having a fireplace, using MERV 13 filters, carbon monoxide detectors, and not building a garage added 12 more points to the total.

(5) LEED Education - Educating the team, the public and home owners through manuals, newspaper articles, workshops, and open houses got 6 points.

LEED Certification Cost Sheet

Calculations

Geothermal System In Phoenix Arizona

GeoComfort GCT036 Geothermal Heat Pump

• 38,900 Btu/hr Cooling Capacity
• 28,500 Btu/hr Heating Capacity
• Desuperheater for Hot Water Heating
• 1000 CFM Airflow Rate
• 2.68 kW at Full Load
• 6000 Btu/hr, 24 GPH Water Heating Capacity
• 4 Feet Head Loss

Vertical Ground Loop

• 1200 Feet HDPE 1.25" Piping
• 6 - 100 Foot Deep Bore Holes
• 7 GPM Flow Rate
• 73 Degree Fahrenheit Ground Temperature
• At Full Load, Loop Temperature
• 108 deg F Incoming Temp
• 97 deg F Outgoing Temp
• 45,000 Btu/hr Heat Dissipated in Loop
• 10 Feet Head Loss

 

 Wilo-Stratos ECO 16 F Pump

• 120 Watts
• At 7 GPM, 24 Ft of Head Loss

Energy Use

• Heat Pump -- 2.68 kW
• Pump -------- 0.12 kW
• Total --------- 2.80 kW

Economics

•  Heat Pump Price -------- $10000
• Ground Loop Price
• at $15 per foot ---- $9175
• Pump ---------------------- $500
• Total Cost ----------------- $19675
• Cost With 30% Rebate -- $13773

----------------------------------------------------------------------

• Annual Costs with Geothermal ------------- $350 
• Annual Costs with AC and Water Heater- $ 1502

----------------------------------------------------------------------

• Payback Time --- 9.4 Years

Other Energy Uses

While heating and cooling represent a significant amount of the energy used by households there are many other areas of energy consumption.  These have been broken down into several groups and can be seen in the following figures.

  

 

Sources:
http://www.google.com/imgres?q=household+energy+consumption+pi+chart&um=1&hl=en&sa=N&biw=1920&bih=950&tbm=isch&tbnid=1wDep1dCm9_EOM:&imgrefurl=http://sunhomedesign.wordpress.com/category/windows/&docid=MuwuV6vzDoi4wM&imgurl=http://sunhomedesign.files.wordpress.com/2007/08/homeenergy.jpg&w=484&h=347&ei=bzeuTryyJo2atwfh9OznDg&zoom=1&iact=hc&vpx=1461&vpy=155&dur=129&hovh=190&hovw=265&tx=125&ty=102&sig=113616092962298287742&page=1&tbnh=141&tbnw=200&start=0&ndsp=45&ved=1t:429,r:7,s:0

http://www.energysavers.gov/your_home/appliances/index.cfm/mytopic=10040

Ventilation Rate

The number of air changes per hour in a building is the number of times the entire volume of air within the building is replaced in one hour.  The recommended number of air changes per hour for a standard home is 4.  To get the ventilation rate of the home, the number of air changes per hour is multiplied by the volume of the home:

4 x 8000 ft^3 = 32,000 ft^3/hr = 533 CFM

Assuming the air density is close to 0.075 lbm/ft^3, the mass flow rate for the home is approximately 40 lbm/min.

Sources:
http://www.engineeringtoolbox.com/air-change-rate-room-d_867.html
 http://www.airinitiative.com/ventilation_rates.html

Heating and Cooling Degree Days and Heating and Cooling Needs for Phoenix Arizona

The table below shows values used in the calculation of heating and cooling needs in Pheonix, AZ.  The calculation is based on the standard ventilation rate of 2000 CFM which can be converted to a mass flow rate of 150 lbm/min.

Using data from October 2010 to September 2011, and the constants listed above, the approximate heating and cooling needs are summed up in the table below:

Sources: http://www.degreedays.net/

Building Materials and Their R-Values

The walls and ceiling of the home are in parallel so the overall U value is calculated by taking the inverse of the sum of the inverses of the ceiling and wall U values.  The Total house U value is 0.02949 Btu/(hr*degF*ft^2).

The surface area of the home is about 2120 ft^2 so the overall thermal conductance (U*A) = 62.59 Btu/(hr*degF).

Sources: http://www.coloradoenergy.org/procorner/stuff/r-values.htm

LEED Part 1

LEED, or Leadership in Energy and Environmental Design was formed by the US Green Building Council to develop an organized method for designing and building green projects. Projects, such as schools, hospitals, homes and many others can be certified under various levels outlined by LEED. With LEED certification, a project is guaranteed to meet several sustainability requirements.

LEED focuses on important sustainability areas to insure that a project truly is green. The site selection criteria considers the impact on the surrounding environment, such as waterways, erosion, and pollution. Efficient use of water is achieved through resourceful appliances and low maintenance landscaping. Energy use, through lighting and heating and cooling is decreased by the use of better insulation or through the installation of clean energy generation. The construction process is also investigated by using sustainably grown lumber and through the reduction of waste.

The ratings system for LEED is based off of 8 criteria; Sustainable Sites, Water Efficiency, Energy and Atmosphere, Materials aand Resources, Indoor Environmental Quality, Locations and Linkages, Awareness and Education, and Innovation and Design. Each of these criteria has a maximum amount of points that can be achieved. These can vary based off the type of project. The points are then added up and the certification level is assigned. These levels go from low sustainability to high, starting with Certified and going up to Platinum.

LEED Profiles

LEED offers a number of example profiles.  These profiles are broken up into the following categories:
1) New Construction
2) Existing Buildings
3) Commercial Interiors
4) Core & Shell
5) Schools
6) Homes
7) Retail
8) Neighborhood Development

All of the categories are fairly self explanatory except for Core & Shell.  According to the LEED website, Core & Shell "covers base building elements such as structure, envelope and the HVAC system".


One of the example profiles listed under Retail was a Chipole Mexican Grill in Gurnee Mills, IL.  The project achieved a platinum rating by receiving an overall score of 53 out of a possible 71 points.  For a more broken down score, see the image below.  This project received LEED certification by building a wind turbine and using the energy for lighting, installing a rain water cistern for the reduction of water use, and installing a program to automatically manage the lights and turn them off when not needed.

References:
Main Site: http://www.usgbc.org/Default.aspx
LEED Home: http://www.usgbc.org/DisplayPage.aspx?CategoryID=19
Project Profiles: http://www.usgbc.org/DisplayPage.aspx?CMSPageID=1721#new_construction
Chipotle Profile: http://www.usgbc.org/ShowFile.aspx?DocumentID=6953