Our home is officially 5-Star Built Green rated. We even have a certificate! In this post we’ll explore some of the features that went into making our home certifiably green. For more background on some of these topics, you can check out some of our earlier posts about green building.
Intangibles
The largest impact green features of a home are not, in a traditional sense, features. Some of the most important decisions came before we even had a floor plan. First is location. Urban infill lots, like the one our home is on, help preserve farmland and undeveloped wilderness areas. By choosing a site that had already been developed, less new infrastructure was needed.
From location we move on to size. By only building as much house as we need, we used less materials and will save energy. At 2700 sq ft, our home is not small, but it is significantly smaller than the 3500 – 4000 sq ft homes we were considering to get similar functionality.
The greenest house is the one you don’t build. The next best thing is a house that will last a long time. We built a high quality, beautiful house because that’s the what we want in a home, but we also hope that it means this home will be used and loved for many decades. In the nearer term, high quality materials and equipment lead to less frequent replacements which means less waste and resources used in manufacturing.
Heating and cooling
The energy used to heat and power a home constitute the bulk of the ongoing environmental cost of a building. Computer models which analyzed our architectural plan predict a HERS score of 56 for our home. That means it should use only 56% of the energy of a standard American home.
Much of this rating is based on how efficiently our home can be heated, and many of the green features of our home aim to decrease the amount of heat transferred between the interior and exterior. High quality insulation, including spray foam at junctions and foam board against foundation walls, increases the R-value of our home. Triple-paned windows with inert gas between the panes also provide better insulation. Our windows have an average U-value of around 0.21. A special coating decreases the amount of sunlight that gets through. The heating system we chose allowed us to have a ventless roof design. Our roof is essentially a foot of solid foam with no holes in it.
Spray foam was used to seal off any leaks that were discovered during our blower door test. We never got official numbers, but the preliminary numbers we saw indicated that after sealing, our house had less than two air changes per hour (ACH) under pressure. For reference, we were told that a house is considered green under about 5 ACH, standard new construction is around 10 – 15 ACH, and older homes without good sealing or insulation can be over 50 ACH. A house is considered passive once it gets to be less than 0.6 ACH. Our house is not there, but it’s close.
To heat our home, we decided to use an air source heat pump. Instead of producing heat, air source heat pumps move heat from the outside to the inside. Even though they are electric, they are highly efficient. Heat pumps made it easy to have have different heating zones, so we can use just the heat we need when we need it. We also take advantage of the efficiency of heat pumps in our water heater. It combines a heat pump and electric heating element. The pump provides efficient heating, while the electric backup provides extra heat when lots of hot water is needed.
Lighting and appliances
Energy Star® appliances reduce the amount of electricity we consume, but other than the Energy Star rating, our appliances are pretty standard. When it comes to general electric usage, most of our green investment went into lighting. Well-placed windows, especially on the southern wall, allow us to use daylight for many of our lighting needs. Taking advantage of natural light saves electricity.
Of course, you can’t use natural light all the time. Especially in the winter, we are dependent on artificial lighting. All of our can lights are LED bulbs. LED lights use less energy. They also last longer which means less waste. Early LED light bulbs produced a harsh light. Newer models provide a soft, warm light that is perfect for general lighting. Well placed light switches are another green feature, although in a subtle way. When the light switch we need is at hand, we are more likely to turn off lights when we leave a room.
Water efficiency
Right now, energy efficiency is the big focus in most parts of the US. As populations grow, our water resources are going to be an increasing challenge. Areas like California and Colorado are already seeing water pressure, and in those regions, green necessarily involves water efficiency. In rainy Seattle, water is less of an immediate concern, but we wanted to plan for the future.
Water from the sinks and showers runs through separate pipes to allow for future greywater collection and distribution. We’ll use the greywater for irrigation once the local laws catch up with the fairly recent Washington state standards.
In the meantime, we use less water because of our low flow toilets. The dual flush option saves even more water by letting the user choose how much water they need. Low flow shower heads also decrease water usage.
Outside the home, our small section of green roof does its part to slightly decrease the amount of runoff that enters the sewer system. Our landscape plans also involve a lot of plants to help decrease runoff. Both green roofs and conventional landscape plantings also help include regional air quality.
Air quality
With such a tightly sealed house, it’s important to ensure good air quality. A heat recovery ventilator ensures that the air in our home is filtered and refreshed regularly. It transfers heat from the outgoing air to the incoming air to save energy.
We also improve indoor air quality by reducing the air pollutants inside. Because they don’t burn anything to produce heat, induction stoves produce fewer combustion products than gas stoves. Even with a well sealed door, exhaust fumes can seep inside from the garage. Eliminating a direct connection between the indoors and the garage further improves air quality.
Conventional paints, finishes, and insulation can make indoor air quality worse than outdoor air quality. Our paint, carpet, cabinets, insulation, and other materials are low VOC. This improves air quality by eliminating chemicals that smell bad may have harmful health effects.
Materials
Being low VOC isn’t the only thing that makes many of the materials used in our home green. Environmentally responsible building materials reduce the strain on our natural resources. Focusing on renewable and recycled resources produces the best long term outcome.
All of the wood for framing was FSC certified. Our SmartStrand® carpet from Karastan contains 37% material that comes from sustainable, plant-based sources, and the whole manufacturing process is designed for sustainability. The CaesarStone® countertops are also manufactured using sustainable practices. The Quartz Reflections finish used in the kitchen is made from recycled content. The Ecotech® tiles we use for our flooring and fireplace are made of over 50% pre-consumer recycled content.
Forward thinking
Technology is constantly improving, and we wanted to take advantage of this in our home. Everything in the house except for the fireplace runs on electricity. Even though electricity is currently more expensive than gas and can be less sustainable, by standardizing on electric appliances we’ll be able to take advantage of the gains as renewable energy replaces non-renewable resources.
We don’t have solar panels, but we did pre-wire for solar. Once we decide the cost/benefit ratio is good enough, we will be able to install them easily. We wired our garage for an electric car charger. We also wired our house for home automation. This will allow us to programmatically control lighting and heating, leading to further electricity savings.
One thing that we hope the list above makes clear is that green building does not have to embody any particular style. All of the strategies applied above could apply just as well in a traditional Craftsman style home or country cottage as in our Pacific Northwest modern home. Most of these things don’t require custom construction either. Many features add very little incremental cost to the home and could easily be integrated into spec construction. Pre-wiring for solar, to take the most extreme example, added only a couple hundred dollars to the cost of the house. Higher quality insulation also didn’t add much cost. While not all new construction is going to be able to reach 5-Star on the Built Green scale, spec homes can do much better than they do right now. If consumers start demanding it — and if builders can start selling homes at a bit of an extra premium if they are labeled green — these improvements will one day be common.