Mountain Architects – Hendricks Architecture

Hydronic Radiant Heating

by 2 Comments

When designing a home, it is important to consider early in the process what type of climate control system the home will be using. Mechanical systems used for heating and cooling work best when they are properly sized, thoughtfully laid out, and have adequate space for all the components.

There are many options for heating and cooling a home. Many homeowners these days are opting for hydronic radiant heat systems, and we get a lot of questions from our clients about radiant heat systems and how best to configure them.  Radiant heat is a great, energy efficient choice for homes where heating is the primary concern and cooling is secondary.

Unlike forced air heating systems, radiant heating warms the objects in a space, not just the air. Because of this, the space will feel warmer and the ambient temperature can be kept lower than it would be in a space that is heated with warm air.  Other benefits of radiant heat are the lack of moving air that can transport dust and allergens, and the ability of radiant heat to maintain an even temperature without noticeable fluctuations.

Hydronic radiant heating uses a central boiler to heat a fluid that is then circulated through piping concealed in the floor system.  The choice of floor system is a major determinant in the performance of a hydronic radiant system, but the choice of floor system should not be based only on what type of heating the house will utilize.

The best radiant heat systems use a concrete floor slab as a thermal mass (see related concrete slab vs. wood framed floors).  Heavy duty plastic tubing is embedded in a slab that is insulated both on the perimeter and on the underside. The amount of insulation depends on the local climate, the level of efficiency desired, and the budget.  The biggest advantage of this system is the substantial thermal mass of the concrete slab, which will store and radiate heat over an extended period of time.  The slab will also double as a collector and storage medium of any passive solar gain. On the flip side, the slab will take a while to heat up, so this type of system does not lend itself well to turning the heat down during periods of inactivity or absence.

Leaks and damage to tubing that is encased in a concrete slab can be costly and difficult to fix, but thankfully they almost never occur.  Problems due to tubing failure can be mitigated by making sure the tubing is thoroughly leak tested and the slab subgrade is well compacted granular material.

When a concrete slab floor is not practical, radiant heat tubing can be embedded in 1½” or more of lightweight concrete or gypcrete poured on top of a wood framed floor.  This is often done on homes that have hydronic heat on upper floors or where a crawl space and wood framed floor is necessary.  Since a 4” concrete slab is too heavy to be supported by a wood framed floor, a thinner, lighter slab is used.  It has significantly less thermal mass, but does provide some heat storage capacity and also helps dampen floor vibrations common with wood framed floors.  Floor framing has to be more substantial for this type of application than it would be for a floor that doesn’t have to support as much weight.

For radiant heat applications where a wood framed floor is preferred or required and gypcrete overlayment is not used there are a few different options.  Warmboard manufactures a plywood subfloor sheathing that has integral channels milled into it that allow radiant heat tubes to sit below the top of the subfloor.  The channels are clad with sheet aluminum that radiates heat upward into the living space and makes for rapid warming of the floor above.  In this sense, it outperforms the concrete embedment systems, but it lacks the thermal mass and ability to moderate temperature fluctuations.  Warmboard is relatively expensive, but by most accounts it functions well and is a viable alternative when concrete or gypcrete is impractical.  Misplaced nails or dropped tools can easily damage the tubing, so pressure testing is required before covering and after flooring has been installed.

The staple up radiant tubing application is the least expensive and easiest system to repair or retrofit.  As a trade off,  it is also the least efficient and easiest to damage.  Staple up systems involve installing the tubes on the underside of the subfloor between floor joists.  The tubes are held in place by staples and sometimes backed with foil faced rigid insulation or installed with integral metal heat transfer plates.  In order to be reasonably efficient, a staple up system needs to have more than code required insulation in the joist bays, and shouldn’t be used where floors are cantilevered out beyond heated space below because of the potential for condensation.

For more on floor system options to use with hydronic radiant heating, see our article on concrete slab vs. wood framed floors.

Tom Russell, Project Architect, LEED AP

Hendricks Architecture specializes in custom mountain style homes.  Our homes have been featured in Timber Home Living, Mountain Living, Green Building and Design, Cowboys & Indians, Cabin Life and other publications.  We’re located in Sandpoint, Idaho.  Subscribe to Hendricks Architecture’s Blog

Previous Post: Concrete Slab vs. Wood Framed Floors

The National Green Building Standard

by Leave a Comment

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

Hendricks Architecture, mountain architects in Sandpoint, Idaho. Subscribe to Hendricks Architecture’s Blog

Previous Post: Sandpoint Mountain Home on the Cover of Timber Home Living

Energy Efficiency

by Leave a Comment

 

At Hendricks Architecture, we specialize in the design of mountain style homes and cabins. We try to make these as energy efficient as possible to save homeowners on long term heating and cooling costs. We educate them on the practicalities, costs and benefits of energy efficiency throughout the design process.

According to Residential Design & Build Magazine, 2008’s most asked for feature in a house was energy efficiency. Currently, Americans use approximately 25% of the world’s energy, and roughly 21% of this is consumed in our homes. Whether we knew it or not, energy efficiency has always been at the forefront of the green and sustainable movements, and is an important part of the LEED process. As architects, we are committed to doing our part to promote and implement energy efficiency in the homes we design.

There are numerous ways that energy efficiency measures can be incorporated into a new or existing home, and often these measures will also enhance the appearance, functionality, and resale value of a home. Some of the strategies are listed below. This is not an exhaustive list but an overview of readily available measures that we can use to enhance the energy efficiency of your home. Many people think adding energy saving measures to a home will initially cost more, and in many cases this is true. In some cases, just making the appropriate design decisions can save energy and not cost any more. It is important to measure additional first costs against long term savings in energy costs, and consider that no one is predicting cheaper energy costs in the future.

DESIGN AND EMBODIED ENERGY

Probably the most fundamental step in creating an energy saving home is to design it for space and functional efficiency. Minimizing non usable space (hallways are one example) and creating spaces that can serve more than one function like Guest/ Exercise or Laundry/ Mud rooms can reduce the overall building area that needs to be heated or cooled. Open plans tend to feel bigger than they are, and save space that would have to be taken up by walls, doors, etc. A good reference for these strategies is Sara Susanka’s “The Not So Big House”.

It is also worth considering the energy use that goes into everything used in the construction of a home. Materials require energy to manufacture, package, store, deliver, etc. Almost every decision made during the design process has some impact on the energy use of your home.

SITING, ORIENTATION, & MASSING

A home should be located on its site to allow access to the sun, protection from prevailing winds, minimize site disturbance, and use natural elements to provide shading and shelter. Stacking a building’s spaces whenever possible reduces the footprint and the surface area through which heat can escape. Below grade spaces benefit from the relatively constant 50 degree temperature of the earth, reducing or eliminating cooling cost during the summer.

WINDOW DESIGN AND DAYLIGHTING

Windows serve several functions in a well designed home. Besides framing views and providing a connection with the outdoors, windows allow natural light to enter, provide free ventilation, insulate against heat loss, and help heat indoor spaces when exposed to direct sunlight. Windows are a crucial element in a home’s design and function, and should be carefully sized, located and detailed. Windows are the weak link in a buildings thermal envelope, so it is important to select quality windows with a low U value.

clerestory-windows

Use clerestory windows to help bring in light

Placing windows to provide ample daylighting will save on lighting costs and the number of fixtures needed. Locating windows to take advantage of solar exposure will reduce heating costs and HVAC equipment required. Direct sunlight does not make for good daylighting, primarily because of glare. The best daylighting utilizes reflected or indirect light from transom, clerestory, or north facing windows. Skylights and solar tubes can be used to provide daylight to interior rooms.

ROOFS, OVERHANGS, AND SHADING

A roof should be designed to shade windows that are exposed to direct sunlight in the summer months. Because the sun is lower in the sky in the winter, roof overhangs should be sized to allow direct sunlight to enter the windows during winter months, maximizing solar heat gain to offset heating costs. On building facades where overhangs are not able to provide shade (gables, etc.), pergolas, awnings, or other shading devices should be considered. Devices that shade lower windows and act as a light shelf for upper windows are particularly effective.

river-windows

Providing broad overhangs reduces summer heat gain, yet brings in the winter sun.

A house’s roofing material also affects energy consumption. Lighter colored or reflective roofing reduces heat gain, and a well ventilated or cold roof will help keep attic spaces cooler, reducing cooling costs.

INSULATION AND THERMAL MASS

It is well know that the better insulated a house is, the more energy efficient it will be. Building codes dictate minimum insulation values for all new construction. Any insulation value beyond the minimum required will be money well spent, especially in roof/ attic spaces where most heat loss occurs. Several insulation products are available that can provide enhanced R-values and provide a tighter building envelope. It is worth considering spray applied foam insulation, blow in blanket, or rigid sheet insulation rather than conventional fiberglass batts. Snow actually adds insulation as well, though is not recognized by building departments.

SIPS panels are also an energy saving system that can be used in lieu of conventional stud framing. In stud/ cavity wall systems, thermal bridging occurs that allows heat to pass through studs that contact exterior materials. SIPS panels have a solid sheet of rigid insulation sandwiched between plywood sheets, and no thermal bridging occurs. They are commonly used on roofs and for wall systems in post and beam construction.

Thermal mass is the ability of a material to absorb and store heat that is radiated slowly. Materials like concrete, stone, brick, and water all have a high thermal mass. A well placed thermal mass will absorb solar radiation or heat from a fire, and radiate it slowly to keep a space warm overnight or for several days. Concrete or gypcrete floors can be heated by solar or gas fired hydronic systems to provide an even heat that feels warmer than heated air at the same temperature.

NATURAL VENTILATION

Operable windows, ceiling fans, and design that utilizes “stack effect” can all be used to passively cool a space, saving energy that would be required by A/C systems. Ceiling fans can be used in rooms with vaulted ceilings to circulate heated air that collects in the peak of the ceiling. Night venting (operating outside air ventilation systems overnight) can also be used to cool a space without using excess energy. Operable windows in bathrooms will also save energy by eliminating the need for exhaust fans when weather permits.

HVAC EQUIPMENT AND APPLIANCES

Heating and cooling equipment are available in a wide range of efficiencies and types. Choosing high efficiency equipment that is Energy Star certified, using insulated duct systems, programmable thermostats, and creating multiple zones for heating & cooling are simple energy saving strategies.

If you live in an area where gas is not available, heat pumps are much more efficient than electric resistance heating. Radiant heating systems with a high efficiency boiler are generally more comfortable and efficient than forced air systems, but are best used in homes that are regularly occupied and should be supplemented with ventilation systems. If a home is used only occasionally, radiant heat may not be the best choice from a cost standpoint, as it takes much longer to raise the temperature of a home to comfortable levels. If you are considering air conditioning with a radiant system, remember that you will be installing two systems since A/C requires a network of ducts to distribute cooled air.

Appliances (especially refrigerators, freezers, and ice makers) consume significant energy. Buying Energy Star appliances are a good way to increase the energy efficiency of your home at minimal extra cost.

We would love to talk to you about ways to increase the energy efficiency of your current home, or to help you design a new home that utilizes these energy saving strategies.

Tom Russell, LEED AP, Project Manager

Hendricks Architecture, mountain architects in Sandpoint, Idaho.

Subscribe to Hendricks Architecture Blog.

Previous Post: Mountain Architecture

LEED Accredidation

by Leave a Comment

Tom Russell of Hendricks Architecture recently became a LEED AP, or Accredited Professional. LEED Accredited Professionals have, according to the United States Green Building Council (USGBC), “demonstrated a thorough understanding of green building techniques, the LEED Green Building Rating System, and the certification process.” The USGBC is a non-profit organization that certifies sustainable businesses, homes, hospitals, schools, and neighborhoods. USGBC is dedicated to expanding green building practices and education, and its LEED® (Leadership in Energy and Environmental Design) Green Building Rating SystemTM.

The LEED certification process has several rating systems that are specific to different building types and project scopes. LEED for Homes is a fairly new product that was launched in January 2008, after a few pilot versions. It promotes the design and construction of high performance green homes. By using a standardized documentation system, LEED for Homes assures owners that their home has meet rigorous criteria for energy efficiency, occupant health, and minimized environmental impact.

The conventional wisdom is that building a green home or doing a green remodel is much more costly. While in many instances this is true, it is not always the case. It is important to consider long term costs when comparing green building to more conventional construction. First costs can often be offset by long term savings in energy use, maintenance, and reduced equipment needs. The USGBC contends that the net cost of owning a LEED home is comparable to that of a conventional home. It is also worthwhile to consider the intangible benefits of a green home, things like improved health, a cleaner environment, and less dependence on conventional energy sources.

For clients interested in achieving LEED certification for their projects, it is important to have a LEED AP involved as part of the design/construction team. They can help guide you through the certification process, which can be complex and time consuming. Having a LEED AP involved also gains your project a point towards certification.

For homeowners interested in a home that is “built green” but not LEED certified, it is always an option to employ green strategies, products and technologies without going through a certification process. While LEED certification offers assurance of a buildings performance, it is possible to have the same level of performance without being certified. For those considering resale value, LEED certification would likely add value to any piece of real estate because it is a verifiable standard that is recognized nationwide.

For any of our clients interested in building a green home or doing a green remodel, we have the knowledge and expertise to assist you. Whether you are going to pursue LEED certification or you simply want a healthy, energy efficient, low impact home, we would love to talk to you about achieving your goals.

Tom Russell, Architect, LEED AP, Hendricks Architecture

Last Post: Is This A Good Time To Build?