You picked the perfect site for your new home but now you’re mired in indecision. Building “green” sounds noble (who doesn’t want to help our planet and create a healthy environment for our kids?) but it also sounds expensive, difficult and confusing. If you’re like most people, you probably assumed that a green home is a simple assemblage of eco-friendly products like recycled timbers, bamboo flooring, and oderless paint – but in fact, choosing products like these is only a small part, and perhaps the least important, of sustainable building. To demystify what it means to build green, we have to start with a primer of basic principles as outlined by Andy Engel in Tools of the Trade - what I like to think of as the Seven Green Building Blocks.
But first, a definition: What is a Green Home? A green or sustainable home is one that is built and functions with a reduced impact on the environment by using resources efficiently, and that provides a healthy, non-toxic environment.
Green Building Block #1- House Design
Here’s a surprise – the size, siting (orientation to the sun) and shape of your house have the greatest impact on how energy-efficient it will ultimately be.
- The larger your house, the more materials it will take to build and the more energy to maintain. This is your most critical decision. Resist the urge to super-size.
- Solar orientation is the second most important factor in determining your home’s energy needs. This is called passive solar design. Try to place the longest walls of the house on an east-west axis. This will give your south facing windows sun in winter and shade in summer. You can also place your garage on the west side of the house or use a porch, roof overhang or trees to shade your west walls.
- The simpler the shape of your house (think New England Salt-Box) the more energy-efficient. Protruding wings and bays increase the exterior skin of the house and let heat escape from the core, much like our own fingers and toes.
Green Building Block #2 – Durability
Like our bodies, houses age, sag and eventually collapse. Water and moisture are the two culprits responsible for the premature aging and final demise of our home, beginning with mold and ending in rot.
- Water can be kept away from the structure through proper drainage, gutter and downspout design, as well as use of special rain-screen walls.
- Moisture can be controlled through carefully installed window and door flashings and with thorough sealing. By minimizing air loss, you keep moisture out and heat in, reducing energy costs by as much as 20%. When moisture is no longer allowed to travel through the exterior walls, it eliminates the danger of condensation in the framing, thus extending the life of your home.
- Use paperless sheetrock to allow any moisture to wick out of damp drywall.
Green Building Block #3 – Energy Efficiency
Your home uses energy such as electricity and gas for light, heat or cooling. You can reduce your need for heat and cooling through passive solar design, which provides a kind of built-in thermal protection. But you also need to reduce thermal loss or leakage with insulation and air sealing. If possible, install your own energy supply.
- Use insulation and builder’s felt in the walls, floor and ceiling to reduce heat loss. Close cavities such as areas behind showers and tubs, soffits and recessed lights with a moisture barrier to prevent heat loss.
- Seal all openings and cracks where air can pass in or out of the house.
- Don’t run HVAC ducts in unconditioned crawl spaces or attics – 20% of the energy can be lost. Fully insulate areas around your ducts and thoroughly seal them.
- Lighting accounts for about 15% of a home’s energy use, but you can reduce that percentage in several ways. Replace inefficient incandescent bulbs with cooler, longer lasting CFLs (compact florescent lights) or the new LEDs (light emitting diodes). LEDs use 1/3 the electricity of CFLs and are more directional for task lighting.
- Decrease energy waste by installing a home automation system with motion sensors to turn lights on and off as you enter or exit a room. A home automation system can also reduce your heating and cooling needs by automatically opening or closing your window shades depending on the outside temperature, and by turning down your thermostat at night and when you are away from home.
- Use energy efficient appliances.
- If possible, invest in solar panels to generate much of the energy your house consumes. Your power company will even buy back any excess electricity from you during times of low use (like when you are on vacation).
Green Building Block #4 – Reducing Waste
You can reduce excessive waste in 2 ways: by using materials more efficiently (and thus, needing fewer of them) and by reusing old materials. In either case you help the planet and your pocketbook at the same time.
- Size your house sensibly. Design your house in four foot multiples to conform to standard wallboard and plywood sheets. You will also dramatically reduce piles of scrap lumber.
- Recycle and reuse building materials such as old concrete and stone as a base for a parking lot.
- Be an avid recycler of glass, plastic and metals in your household. Set up a compost bin to turn your food scraps into rich mulch.
Green Building Block #5 – Water Conservation
The aim here is twofold: you need to both reduce the amount of water your family consumes, but also channel the rainwater that falls on your lot back into the soil.
- Use low-flow shower heads and toilets to reduce water usage.
- Use automatic sprinklers with moisture sensors to regulate water use and prevent over-watering.
- Use native and drought-tolerant plants.
- Use porous concrete pavers on driveways to allow rainwater to percolate down into the earth and recharge aquifers.
Green Building Block #6 – Indoor Air Quality
We’ve already mentioned how proper sealing and insulation can prevent moisture and mold in the home, but an air-tight home has its own problem – it traps all gases and fumes inside the home, thus polluting the air you breathe. Particle board and OSB off-gas formaldehyde; paints, finishes and car products contribute VOCs (volatile organic compounds); gas stoves and poorly vented gas appliances contribute carbon monoxide to the stew. There are two ways to clear the air and breathe easier: use products that are less toxic, and change your ventilation system.
- Use building materials like plywood in place of OSB to reduce formaldehyde buildup. Some carpets are not only made from recycled nylon, but also boast no VOCs. Natural floor adhesives, paints and finishes also offer zero emissions.
- Use a dedicated air supply for furnaces and water heaters to prevent gases from back-drafting into the house.
- Install a heat recovery ventilator (HRV) system to bring fresh outside air into living spaces while exhausting air from bathrooms, kitchens and laundry rooms.
Green Building Block #7 – Green Products
We’ve already shown how using green products can make a difference to the environment and your health. With more and more eco-friendly products to choose from, let’s sort out the various types and shades of green on display.
- Products made from recycled materials: concrete made from fly ash (a waste product of coal power plants), carpet made from recycled nylon (and recyclable after its life), synthetic stone counter tops made from recycled paper, glass and cement.
- Reused building materials: salvaged timbers, lumber, brick and stone.
- Products from sustainable resources: cork flooring from the cork oak tree (also durable, sound and heat insulating and hypoallergenic); bamboo flooring from fast growing bamboo.
- Energy-efficient products: solar panels, Energy Star appliances, home automation systems, CFL and LED lights.
- Non-toxic products (both in their manufacture and use in the home): low odor paints and finishes, carpets and plywood.
With this primer in hand, you now know the difference between a CFL and a VOC. As you can see, the most critical choices for a green home are made when you first sit down at the drafting table. Your dream home will be energy efficient, durable and safe if you design it using all seven green building blocks. Your friends might turn green with envy.