Project 2 - Report

Miranda Williams

Project 2 – Report

Introduction

This report will explain how planting trees will benefit Marin City, California. The project funding for the planting of trees must not be forfeited. Energy savings will be discussed first. Next, an estimation of how many trees are needed to offset half of the energy costs of the new Marin City Center will be calculated.

Marin City Current Tree Energy Savings

Marin City has about 119 acres of trees. This figure was calculated by reclassifying the Marin City aerial raster into 3 classes: trees, grass, and impervious surface. However, this technique is not completely accurate. When classifying the image, some trees were classified as grass and vise versa. This happens because some parts of the trees were the same color as the grass and were classified incorrectly.

After the acreage of trees was calculated, I used the average tree width of 10-14 inches to find about how many trees there are per acre. The DBH table shows that there are about 28 trees per acre of the 10-14 inch size. The following formula gave me an estimate of the total amount of trees in all of Marin City:

28 trees per acre*119 acres of trees= 3332 trees

With this estimation of 3332 trees, the current annual energy savings can be calculated.

$4.39 savings per tree per year * 3332 trees =$14,627.28 annual savings

These calculations clearly show that trees are a valuable necessity in city landscaping. The funding for the project must not be sacrificed.

Marin City Center

The proposed Marin City Center will include a community center. Enough trees must be planted in the City center to offset half of the community center’s annual energy usage. The Marin City Center will be located within the boundary of Phillips Drive and Drake Avenue, as shown in the map below.

Using the table found at www.eia.doe.gov, I found the monthly energy usage for a commercial building. The new community center is considered commercial. This is just the average. Many factors contribute to the energy usage of a building such as size, etc.

5765kwh (energy usage for one commercial building a month)*12 Months=

69180kwh per year

The trees must offset half of the energy usage. Therefore the trees must offset 34,590 kwh.

Using table 5, I found how much kwh a single tree saves during the heating and cooling months. This was for climate only trees (>12 m from buildings). Annual cooling savings for a single tree is 22kwh. Annual heating is 26kwh. This totals 48kwh per tree per year. To find how many trees need to be planted to offset the energy costs by half, I used this formula:

34590kwh/48kwh per tree =721 trees

The area where the new Marin City Center will be built is about 8 acres. Since there are only about 28 trees per acre, this only allows for only 224 trees out of the recommended 721. This number only accounts for climate only trees. Trees that are planted closer to buildings will save more energy. Therefore less than 721 trees will be needed.