The National Green Building Standard

The green building movement has generated quite a following in the last 5 or 10 years, and what used to be a somewhat fringe idea is now becoming part of mainstream culture. Advertisements for products and services across the spectrum are full of sometimes dubious claims of how environmentally friendly they are, and efforts are being made in many industries to create a metric to quantify how “green” something really is.

The building industry has been a leading force in the establishment of meaningful rating systems for measuring the environmental impact of common materials, methods, and design practices used to create modern buildings. The LEED rating system was developed in 2000 by the U.S. Green Building Council, and soon became the industry standard, perhaps because it was the only standard. It has evolved from a broad scope that attempted to encompass all aspects of building construction into a suite of specific rating systems that target specific project types.

In 2007, the International Code Council (ICC) and the National Association of Home Builders (NAHB) partnered to create a nationally recognizable standard for measuring sustainable building practices called The National Green Building Standard. It provided a much needed tool for comparing the relative merits of single and multi-family homes built using established or innovative products and practices. Since it is specific to the residential sector of the construction industry and a companion document to the ICC suite of model building codes, many builders and homeowners are choosing to pursue certification under the National Green Building Standard.

The Green Building Standard is similar to LEED in many ways. Both utilize a point system that is used to achieve one of four different levels of certification. In the National Green Building Standard, the levels are Bronze, Silver, Gold, and Emerald. Points are earned for employing green building practices that fall into categories covering the basic tenets of sustainable design and construction:

1) Site selection, design, & development

2) Resource Efficiency

3) Energy Efficiency

4) Water Efficiency

5) Indoor Air Quality

6) Owner education on systems operation and maintenance

7) Innovative practices

In both the LEED and NAHB rating systems, an independent verifier is used to determine a project’s level of achievement.

In general, the NAHB Green Building Standard provides rewards for practices that exceed the basic requirements of building codes, especially as they relate to minimum insulation levels, plumbing fixture flow rates, and ventilation requirements. Emphasis is placed on high efficiency heating / cooling, minimizing generated waste, using durable, renewable, salvaged or recycled materials, and avoiding products that contribute to poor indoor air quality or have adverse environmental impacts.

At Hendricks Architecture, we have designed a couple homes recently that will be seeking certification under The National Green Building Standard. Scott Schriber of Selle Valley Construction will be building both of them, and he has constructed several NAHB certified green homes in the last few years. He estimates that it costs an additional 3%-5% upfront to build a home that achieves Green Standard certification.

Green Building Standard Home

A home designed to achieve certification under the National Green Building Standard

Our experience has been that when clients are considering if they should build a high performance/ low impact home, upfront cost is almost always a factor. When trying to decide if “going green” makes financial sense, it is important to remember that a home built to The National Green Building Standard (or other rating systems) will benefit from substantial long term energy and maintainace cost savings, improved indoor air quality, and enhanced resale value. Financial considerations aside, many homeowners are opting to build high performance green homes simply because they value the peace of mind that comes with creating a healthy, durable place for their families to live.

Tom Russell, Project Architect, LEED AP

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New Energy Code Requirements for Insulation

As of January 1, 2011, many states, including Idaho, adopted new energy code requirements with the 2009 International Energy Conservation Code (IECC). The new code has stricter requirements for the energy efficiency of the building envelope (a technical term for the part of a building that keeps the interior warm, dry, and comfortable). The new code requires a roughly 8-10% upgrade in building thermal efficiency from the previous code.

The biggest changes affect insulation values in ceilings, below grade walls, and to a lesser extent, above grade exterior walls. The insulation requirements vary within 8 different climate zones. North Idaho and much of the Intermountain West are in climate zone 6, which has only slightly lower insulation requirements than zones 7 & 8. Zones 7 & 8 encompass the very coldest parts of the country.

Here’s a quick overview of the new requirements:

  • Ceiling insulation values have been increased from R-38 to R-49. (The R-value is a measure of thermal efficiency – the higher the number the more efficient the insulation). This is significant and potentially costly to homeowners, especially if they want vaulted ceilings. Typical roof framing members are not deep enough to accommodate enough conventional fiberglass insulation to achieve this high R-value. There are options that can be employed to meet this requirement and still have vaulted ceilings.
  1. Use deeper rafters. This is potentially expensive, an inefficient use of resources, and generally not recommended unless structural requirements dictate it.
  2. Use urethane spray foam insulation, which has a much higher R-value per inch. This product is more expensive than fiberglass insulation, but is an excellent air seal and eliminates the need for venting, which is sometimes difficult on complex roofs.
  3. Use fiberglass insulation in the rafter space, and then a continuous rigid board insulation on either the ceiling below the rafters or on the roof above the sheathing. This reduces thermal bridging, which is a major source of heat loss in stick frame construction. Depending on the application, it may be better to put board insulation on the interior; putting it on the roof is physically easier but makes attaching some types of roofing problematic.

The code does allow for some R-value reductions if certain details are used, and there is an allowance for a maximum of 500 S.F. of vaulted ceilings with R-38 insulation value, subject to some restrictions.

  • Basement wall insulation values have been increased from R-13 to R-19. These numbers are for insulation in wall cavities, if continuous board or spray foam insulation is used R- 15 is required. This accounts for the reduction in heat loss through thermal bridging, as mentioned above. One implication of this is that basement living space will potentially be reduced because walls need to be thicker to accommodate more insulation. Use of an ICF foundation system is an effective way to achieve this R-value without losing interior space.
  • Exterior wall insulation value has been increased from R-19 to R-20. This is significant because conventional fiberglass batt insulation is not able to achieve R-20 in a 2 x 6 wall. As an alternative, the code allows for a cavity insulation value of R-13 if a continuous board or foam insulation of minimum R-5 is used as a supplement. This is, again, an acknowledgement of the value of reducing thermal bridging. Urethane spray foam insulation can easily achieve R-20 in 2 x 6 stud cavities.

The new IECC has upped the ante for reducing building energy consumption, and future versions of the code promise further improvements. I have always been an advocate for maximizing the thermal performance of any new building, and hyper-insulating is a very effective means of achieving that goal. Money spent up front in insulation will be rewarded through reduced energy costs, smaller mechanical systems, and enhanced comfort levels for building occupants.

Tom Russell, LEED AP, Project Architect

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Deconstruction vs. Demolition

Recently I read an article in the Seattle Times Home and Garden section about deconstruction versus demolition, both of which I’ve had experience with as an architect. “On average, more than 75 percent of a home can be reused and recycled”, said writer Stacy Downs.

When you hear the term “tear down”, most homeowners simply have the contractor tear down a home, take it to the dump, and start a new home with new materials. The art of deconstruction, where a contractor takes the time to disassemble the light fixtures, cabinetry, doors, door handles, plumbing, and other parts of the house, is becoming more and more in vogue.

Some of your plumbing and light fixtures can be reused on your new home. Your original concrete foundation, garage floor, basement, patio, driveway and brick chimney could be crushed and used for your new home’s foundation backfill, potentially saving you thousands of dollars.

In the case of the mountain style homes we design, recycled timbers are extremely valuable. Not only are these rustic timbers physically beautiful, but they are also sometimes bigger and longer than those commercially available, not to mention the strength of the old-growth wood.

I designed a new home a few years ago in Bellevue, Washington where the old home was deconstructed. It was the homeowner’s idea, and at first I had thought they would lose money in the deal. Deconstruction is much more labor intensive and the costs of deconstruction are initially higher. However, if you’re willing to wait until after taxes, you could actually earn money if you have it appraised for the value of the salvageable structure.

Not only could you get tax benefits, you could also get extra LEED points, as well as help ease the minds of the environmentally conscious. More than 30% of waste that goes into landfills consists of building materials. For more info, or to purchase recycled goods, look up your local Habitat for Humanity ReStore resale outlet. Proceeds help your local Habitat affiliates fund the construction of Habitat homes within your community.

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John Hendricks, AIA Architect

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Residential Heating Options

As architects, our clients are always asking for guidance on what type of heating or cooling system will be best for their home. The answer is not a simple one, and making a decision usually involves weighing a combination of personal preference, initial vs. life cycle costs, practical constraints, and climate considerations. There are a lot of residential heating options out there, and deciding which one is appropriate for your situation will not only impact your future utility costs, but also your level of comfort and satisfaction with your home.

Some of the practical considerations that weigh in on the decision are:

1. Climate

  • If you live in a hot climate, cooling will be the primary consideration. Heating will be a secondary concern and may only be required very occasionally.
  • In most areas of the country, both heating and cooling are required, depending on the season. Choosing a system that does both efficiently is important
  • Some mountain environments don’t require cooling, or natural ventilation can be used to control the comfort level and mechanical air conditioning is not necessary.

2. Availability of energy sources

  • Depending on location, electricity, natural gas, or other public utilities may be unavailable or prohibitively expensive.
  • Renewable energy sources may be available and cost effective to utilize (solar in the Southwest, wind on the coast, geothermal near a large water body)

3. Relative cost of energy

  • Electricity rates vary significantly
  • Natural gas is typically a good value, but not always available
  • Heating oil and Propane are usually delivered by truck to your site. They may or may not be less than electricity, but delivery can be subject to weather and seasonal accessibility challenges.

4. Initial costs vs. life cycle costs are always a consideration. In general, the systems that cost the most to operate are the least expensive to purchase and install. A system that uses very little or no energy may be expensive to buy, but might pay for itself in a reasonable time and end up saving money in the long term. Energy efficiencies of the different systems vary greatly.

5. Personal preferences vary

  • Some people find moving air (especially cool air from air conditioning) to be uncomfortable.
  • Individuals with allergies or respiratory ailments may be affected by forced air systems, which tend to re-circulate dust and other airborne contaminants.
  • Some systems are better for zoned comfort, allowing inhabitants to vary temperatures in different areas of the home.

6. Space requirements may be an issue

  • Duct systems may need dropped ceilings, soffits, and vertical chases
  • A/C condenser units need to be outside and near mechanical room
  • Hydronic systems work best in concrete floors or with a gypcrete overlay
  • Baseboard heaters take up floor space and affect furniture layouts

Here is an overview of the commonly utilized systems and their pros & cons:

Electric resistance heat (baseboard, fan forced wall heaters, forced air)

Pros-

  • Inexpensive upfront cost
  • Easy to control heat levels in individual rooms
  • Doesn’t require gas service
  • Can be turned down during the day to save energy

Cons-

  • Inefficient and expensive to operate
  • Requires a separate system if A/C is desired
  • Dry heat, requires humidification in most climates
  • Most systems don’t utilize outside air, so a separate air exchange system is required
  • No heat during power outages

Best use-

Not recommended unless gas service is unavailable and low cost is top priority.

 

Electric heat pump: (forced air system with heat exchanger, basically an A/C system run in reverse)

Pros-

  • Doesn’t require gas service
  • High efficiency
  • Fast response – changes the ambient air temperature quickly
  • Can be turned down during the day to save energy
  • Moderate initial cost
  • Can be retrofit to existing forced air system
  • Works equally well for heat & A/C

Cons-

  • Requires a condenser unit for each zone
  • No heat or cooling during power outages
  • Requires a duct system
  • Re-circulates inside air

Best Use-

Where gas is unavailable or expensive. Heat pumps are best used where heat as well as A/C are necessary.

 

Gas fired forced air: (conventional furnace, with or without A/C)

Pros-

  • Natural gas is usually inexpensive relative to other sources
  • Can be high efficiency depending on equipment and design
  • Moderate initial cost
  • Fast response – changes the ambient air temperature quickly
  • Can be turned down during the day to save energy
  • A/C function is optional, and can be upgraded for minimal cost
  • Popular system, so repairs are usually fairly easy and inexpensive

Cons –

  • Gas availability varies
  • If required, propane and heating oil are expensive and require a tank
  • Requires a duct system
  • Re-circulates inside air
  • Gas leak and Carbon Monoxide hazards exist
  • No heat or cooling during power outages

Best Use-

When natural gas is available and inexpensive, space required for ducts is not an issue, and initial cost is a primary consideration.

 

Hydronic radiant floor heating: (heated liquid circulated through a network of concealed piping)

Pros –

  • Heats objects rather than the air, so it is more comfortable heat.
  • No re-circulated air, so indoor air quality is better
  • No visible appliances or registers
  • No sensation of moving air
  • Floor, furniture and other objects are always warm / cool
  • Boiler can be used for domestic water heating as well
  • In rare cases, wood can be a fuel source rather than gas

Cons –

  • Higher initial cost, moderate operating cost
  • Slow response time – can take several days to change the temperature significantly
  • Can’t be turned down for short time periods
  • Cooling function doesn’t work as well as forced air – condensation can be an issue
  • Retrofitting, modifying or expanding system can be difficult
  • Needs concrete, gypcrete, or other thermal mass to work well
  • Requires ventilation system to exchange air

Best Use-

When the highest level of thermal comfort is desired. Ideal system when heating is the primary function, cooling is secondary, and short term temperature fluctuation is not required.

 

Electric Radiant Heat: (Similar to hydronic, except for the following)

Pros –

  • Less expensive initial cost
  • Works best with thermal mass, but can be used without
  • Can be used for small areas to supplement other systems
  • Can be supplemented by solar photovoltaic panels

Cons –

  • Expensive to operate
  • No cooling function

Best Use-

When the comfort of radiant heat is desired, and gas is unavailable or expensive. Electric radiant is popular for small areas (bathrooms, kitchens, mudrooms) in homes that have non radiant systems.


Fireplace or wood stove

Pros-

  • Add to the ambiance of a space
  • Wood heat feels good, similar to radiant
  • Fireplaces and stoves can be gas or wood burning
  • Visual as well as functional benefit
  • Provide heat during power outages

Cons-

  • Fireplaces and stoves take up floor space
  • Firewood requires storage space and can be messy
  • Wood burning appliances require cleaning and maintenance
  • Potential fire hazard
  • Aren’t effective at circulating heat to large spaces

Best Use-

Fireplaces and woodstoves are great at supplying supplemental heat, but are not always feasible as a primary heat source. They are common in mountain homes, and can be a huge asset during prolonged power outages.

 

Some alternative energy sources can be used with heating and cooling systems to cut operating costs and environmental impacts. Some of the options that are available include:

Solar hot water – Solar Panels (usually roof mounted) can supply heated water to hydronic systems. Limited to cooler climates that have predominately clear skies.

Solar Photovoltaic – Solar cells in a variety of forms generate electricity that can be used to supply electric heat pumps, radiant or resistance heating systems.

Geothermal – Captures heat from the earth or large water bodies to supply hydronic systems or electric heat pumps. Despite what common sense would imply, heat can be extracted from earth or water that is at relatively low temperatures (32-55 deg Fahrenheit) and used to heat water or air to temperatures in the human comfort range.

Wind or moving water can turn generators that produce electricity. These systems are less common, but if the environment you live in has one of these energy sources, it can be utilized to heat and cool a home.

Upfront costs for alternative energy systems tends to be higher than for conventional public utility powered systems, but the energy savings can be substantial. It is worth considering the cost and environmental benefits that alternative energy systems can provide when making the decision of which type of climate control system to use in your home.

We have seen many of these systems installed in the mountain homes we design, and can help you make informed decisions on which system will be best for your project. We try to stay informed of the best technologies because we know how important the climate control system is to the proper function and overall enjoyment of a quality home.

Tom Russell, LEED AP and John Hendricks, AIA Architect

Hendricks Architecture, mountain architects in Sandpoint, Idaho.

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