Green Building Program
San Diego Habitat for Humanity is going GREEN! A recent focus of San Diego Habitat for Humanity has been the incorporation of core elements in green building, while maintaining "simple & decent" affordable homes. Habitat for Humanity is carefully working to preserve the balance of funding, volunteer-friendly building, as well as integrating green building techniques into the design and construction our the homes. Among the core elements are: Site, Energy/Atmosphere, Water Efficiency, Indoor Environmental (Air) Quality, and Materials and Resources; each in an attempt to optimize the goals of "going green." Going green fundamentally entails the conservation of resources as water or energy by means ranging from proper installation to the use of drought tolerant landscaping. Thus far, we have made many significant adjustments in the design and construction of our homes pertaining to many of the core green building elements in hopes of encouraging other organizations and development projects to implement similar environmentally conservative practices. In addition, Habitat for Humanity is aiming to make the homes increasingly self-sustaining, reducing the costs of maintenance for the owner as well as the need for repairs or upgrades.
In regards to modifying the construction of the homes, Habitat for Humanity has implemented a site management program organizing used materials for recycling or reuse. This program entails the set up of multiple bins labeled for different materials to be recycled so as to ensure the proper disposal of site materials. During construction, Habitat for Humanity tries to minimize the amount of soil exported from the site which helps in the conservation of energy that would be needed to transport the soil.
Habitat for Humanity has utilized value engineering in order to reduce material use. Some modifications that have resulted from value engineering are the increase of stud spacing saving both resources and money.
In order to assist in heating during the winter and cooling during the summer, we have utilized the practice of passive solar heating which is based on the house overhangs. Due to the overhangs being advantageously south-facing, during the summer months when the sun is higher, the sun will be blocked by the overhangs. However, contrasting in the winter months, the sun is lower so the overhangs do not prevent the sun rays from entering the house and heating it during the day.
For sheathing, we have substituted sawn lumber with OSB which is an engineered lumber that is manufactured from used materials and fast-growing farm trees. Due to the nature of OSB, the use of small pieces of wood reduce the dependence of older growth trees, and the lower formaldehyde content adhesive also contributes to improved indoor air quality.
Tiles are used for the flooring of the homes which is environmentally beneficial because they are composed of recycled or reusable materials, making use of otherwise wasted by-products.
For the home sidings, cement based HardiBoard Planks are used which is not only beneficial as an extremely durable material but due to the nature of cement it does not have a large environmental impact in regards to energy consumption, emissions, waste, water, and CO2 generation. Cement is primarily composed of limestone which is plentiful as well as other recycled materials as fly ash together reducing the energy inputs necessary for production.
Habitat for Humanity is beginning to use standing seam metal roofs instead of their traditional asphalt shingles. This form of roofing is largely beneficial to the environment while also improving energy efficiency. Its environmental benefits include the reuse of materials, little waste, and minimal need to replacement or maintenance due to is resistance to water, cracking, shrinkage, and eroding. Finally the metal roofs reflect the sun reducing the need for cooling and saving energy. An additional benefit, particularly in San Diego, is that the standing seam metal roofs are fire resistant.
None of the homes have air conditioning but are instead supplied with whole house fans ensuring that fresh air enters the house, exchanging the air at least once a day. Complimenting these fans, are functional window which circulate the air and assist in natural cooling.
The paint for Habitat for Humanity is provided by Valspar whose paint is characterized as low VOC (Volatile Organic Compounds) paint indicating that they release a reduced amount of harmful smog-producing pollutants into the air as it is being applied or as it is drying, thus improving the air quality.
The landscaping for the housing projects either have minimal or no grass, and is instead landscaped with drought tolerant plants and trees conserving water. The trees used tend to be fruit trees and shade trees which provide shade for natural cooling and through strategic arrangement can reduce cooling costs up to 25% to 40%.
All of the lighting is Title 24 or better, which for now entails the use of fluorescent light bulbs significantly reducing energy consumption. In the recent El Cajon project the electricity is being generated by solar panels installed on the roof, which increases the homes� ability to be self-sustaining reducing fossil fuels as well as energy costs.
To help with air circulation and the reduction of heat, the living room and master bedrooms are installed with fans, which use considerably less energy than air conditioning.
Double pane windows are used on all of our homes, providing greater insulation as well as noise control. They have a U-factor value of 0.35 indicating that they are energy efficient. The U-factor indicates the rate of heat loss and the windows resistance to heat flow. Any value of 0.35 or below are considered to be very efficient.
Tankless water heaters are used in Habitat for Humanity homes, which due to their high efficiency save energy, water, money, and space. Contrasting the standard water heater, tankless water heaters do not constantly heat and reheat water, but instead heat the water on-demand allowing for the reduction of water heating costs of up to 60%. The tankless water heaters are currently supplied by Rinnai.
Habitat for Humanity uses a drip irrigation system in order to minimize water use and increase efficiency. In contrast to traditional sprinkler systems with an efficiency ranging from 50 to 70 percent, the drip irrigation system exceeds 90 percent efficiency by slowly applying water directly to the soil and generally at the roots of the plant.
In combination with the drip irrigation system, smart irrigation controllers are used to monitor the water used. Automatically adjusting irrigation by using sensors and weather information, the smart controllers can manage water times and frequency which results in a reduction of outdoor water use by up to 30 percent.