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Residential Heating System Basics

Residential Heating System Basics

The ability to employ mechanical systems to automatically modulate the temperature (and often humidity levels) of our homes is a radical change from the previous centuries of human habitation. Our heating and cooling systems are often complex and high performance devices that give us fingertip control over indoor climate that would have been unthinkable less than a century ago. Until quite recently, the devices we used to achieve stable temperatures were functional but quite inefficient, using large quantities of fuel to meet our thermostat settings. A lot of development has gone into increasing efficiency, and in many cases this has come with increased complexity and cost. The following residential heating systems basics will help you understand your options.

Though most heating devices are intricate systems, it is quite easy to understand the basic technology behind each of them. It is worthwhile as a homeowner to understand these systems, and not leave it to company reps or installers to provide selling points.

It is easiest to think of heating and cooling systems as falling into categories of means of heat production and means of heat delivery. From this understanding, it is possible to narrow down the pool of options to those that suit the needs of a project.

Means of Heat Production

Despite all the competing products in the heating and cooling market, there are just four kinds of heat production. Details for each system are provided individually later in the chapter.

1) Solar Heat

In effect, all sources of heat are based on solar energy, as the fuels used in every heating system are the result of captured and stored solar energy. However, this classification of heating systems is based on direct harvesting of solar energy in real time. Heat from the sun can be collected (and sometimes concentrated) in, on or near the building and distributed for use throughout the building.

There are three basic types of solar heat, which may be used in any combination.

Passive Solar – A building may be designed with sufficient glazing on the sunny side of the building to allow for a measurable increase of indoor temperature when the sun is shining.

Active Solar Air – Collector units are used to gather and concentrate the sun’s heat in a flow of air that is supplied to a heat exchanger or directly to the building.

Active Solar Water – Collector units are used to gather and concentrate the sun’s heat in a flow of liquid that is supplied to a heat exchanger or directly to the building.

This category of heating devices does not include photovoltaic cells, which use solar energy to generate electrical current, and not directly to produce heat. Heat created by solar electric current is considered in the category of electric resistance heating.

Solar energy systems may appear to have low efficiency rates, with figures ranging from 10-70%, depending on ambient temperatures and type of collector, among other factors. These figures represent the percentage of available potential energy from the sun: approximately 1000 Watts per meter squared (W/m2) for a surface perpendicular to the sun’s rays at sea level on a clear day. A reduced figure of 800 W/m2 is often used in generating comparative figures for solar devices. While it is beneficial to increase efficiency rates to produce more heat from less collector area, the efficiency rates aren’t directly comparable to those of combustion devices as no sunlight is actually “wasted” and no harmful byproducts are generated by the solar energy that is not absorbed by the collector.

Solar heating systems do not generate emissions, fuel extraction and transportation impacts or air pollution, with the exception of those systems that use non-solar energy to drive small pumps or fans.

2) Combustion Devices

This category of equipment is by far the most prevalent. Regardless of the type of system and fuel used, all combustion devices burn a fuel and extract heat from the flame. All these devices rely on a supply of oxygen to react with the fuel and create the flame, an exhaust to allow spent combustion gasses to exit the unit and the building and a heat exchanger that passes the heat from the flame to the delivery system that supplies heat to the home. There are two broad categories of combustion devices:

Gas/Liquid Fuel Combustion – These are the dominant players in the market, and include all the various forms of fossil fuel such as natural gas, propane and oil, as well as bio-fuels like biodiesel and vegetable oil.

Solid Fuel Combustion – This group includes wood burning devices, as well as those that use other forms of biomass such as compressed pellets.

Combustion devices have efficiencies that range from 50% for some wood burning devices to 98% for some new gas burning devices. This means that less than all of the heat potential of the fuel is captured and used to supply the building.

Exhaust gasses from combustion devices differ depending on the fuel used and the combustion efficiency and conditions, but all devices release CO2 and a host of other byproducts with environmental effects.

3) Heat Pumps

This category of equipment is widely used in the form of air conditioners, and has started to capture a larger portion of the heating market. These systems use the refrigerant cycle to transfer latent heat from a source and deliver it to a destination or heat sink. It can be difficult to understand exactly how a heat pump works, but it is worth figuring out the principle at work in order to decipher manufacturer claims. Heat pumps can seem like they magically make heat from no heat if the refrigerant cycle is unclear.

heat pump explained

Heat pump explained

Mechanical energy (usually in the form of an electric motor) is used to cycle a volatile refrigerant that is chemically designed to boil and condense in the expected operating temperature range of the heat pump. The refrigerant is in its liquid state when it absorbs latent heat from a source (air, ground or water for most residential purposes). This heat does not need to be in a temperature range that feels warm or hot to the touch, as the refrigerant’s chemical properties will ensure its boiling point is at or near to the source temperature. Once the refrigerant has passed through the heat collection exchanger, the electric compressor pressurizes the warmed refrigerant, which is at or close to its boiling point. The pressurization causes the refrigerant to become a hot vapour. This hot vapour passes through a heat exchanger where the heat generated from pressurization is dispersed. The refrigerant condenses as the heat is removed. Condensed refrigerant now passes through an expansion valve where the pressure is released and the refrigerant returns to its liquid state and returns again to the exchanger and repeats the cycle until a thermostat indicates the proper room temperature has been reached.

It is the process of boiling and condensing a refrigerant under different pressures that creates the heat exchange. Useful heat exists in this boiling/condensing cycle, regardless of the actual boiling point of the refrigerant. As long as heat collection side is above absolute zero, there will be heat to extract. Consider the home refrigerator: cold is not being generated in the freezer, rather heat is being extracted from the freezer and released via the heat coils on the back of the fridge.

The refrigerant cycle can happen in either direction, and some types of heat pumps are designed to work as both heating and air conditioning units by reversing the direction of flow of the refrigerant.

There are three broad categories of heat pumps for residential use:

Ground Source Heat Pumps (GSHP) – The source of heat is the stable temperature of the ground (below the frost line in cold climates). Base ground temperature is very reliable and steady, and the ground provides a large surface area and capacity for heat exchange. Most GSHPs are reversible and can provide heat and cooling.

Air Source Heat Pumps (ASHP) – The source of heat is the ambient air temperature outside the building. As this temperature can be quite variable, different refrigerants and/or pumps are used to continuously extract useful heat from changing air temperature. Most ASHPs are reversible and can provide heat and cooling.

Air Conditioners (AC) – The source of heat is the uncomfortably warm air that is affecting comfort. These units provide cooling only.

Efficiencies for heat pumps far exceed those of combustion devices. The amount of energy input to provide compression of the refrigerant is significantly lower than the amount of heat energy that is extracted from the process and this how manufacturers claim efficiencies ranging from 200-500%. The heat is not “free” as some claim, but for every one unit of electrical energy applied to the system, 2-4 units of heat are returned. The systems don’t work without the electric motors, but they are much more efficient than combustion devices.

While there is no combustion and therefore no exhaust gasses from heat pumps, environmental impacts will vary depending on the source of electricity used to power the system. The refrigerants used can also be powerful greenhouse gasses, though stricter regulations are resulting in less damaging formulations.

4) Electric Resistance Heat

Electrical current can be passed through a resistive conductor to produce heat. This type of heat production is known as resistive, Joule or ohmic heating. The heat produced is proportional to the square of the current multiplied by the electrical resistance of the wire or element. The amount of current supplied can be adjusted to vary the heat output. Heat energy may be supplied through convection and/or infrared radiation depending on the kind of heating element used.

Efficiency of electrical resistance heating is considered to be 100%, as all the potential energy in the current is converted to heat. However, many sources of electrical power are less than 100% efficient, so overall system performance must take into account the type of generation used to supply the electricity.

The type of generation will also determine the environmental impacts, which can range from high for coal-fired power plants (with delivered power efficiencies as low as 35%) to negligible for renewable energy streams like solar, wind and microhydro.

Means of Heat Delivery

Heat flow always moves from a warmer object to a colder one. Heat flow can occur in three ways:

Conduction – Heat energy is transferred from a warmer object to a colder one by direct contact.

Convection – Heat energy is transferred from a warmer object to the air surrounding the object and then to cooler objects in contact with the warmed air. Warmed air become less dense and rises, creating convection currents that affect objects in the path of the current.

Radiation – Heat energy is transferred from a warmer object to a cooler object by electromagnetic waves, caused by energy released by excited atoms.

Heat transfer

Heat transfer

These neat categorizations do not adequately describe heat delivery systems in buildings, as any heating system will warm a space in all three ways to varying degrees. Consider the element on an electric range: anything that touches the hot element will be heated by conduction. At the same time, air near the element will be warmed, become buoyant and warm objects near the range by convection and the heated element will radiate heat to nearby cooler objects, warming the surface of the range and nearby utensils that are not touching the element nor in the path of heated air.

Certain heating systems will rely on one of these methods of heat flow more than others, but cannot be categorized by a particular kind of heat flow.

Instead, it is more useful to consider heating systems in regard to the medium of delivery, of which there are two. Almost any kind of heat production can be twinned with any kind of delivery system.

1) Air Delivery

Passive Air Delivery – These systems rely only on natural convection currents to move heat from a source to the desired locations in the building. No fans or ducts are used to direct warmed air.

Active Air Delivery – These systems use some form of mechanical energy to force air movement in a desired direction. Ductwork is often used to deliver a concentrated stream of warmed air to a particular location.

Air can be an effective medium for delivering heat in some circumstances. It is not very dense, and it is therefore easy to change the temperature of a large volume of air quite quickly. The energy required to move air from one location to another is low, as it flows and changes direction easily and large volumes can be moved quickly. Natural convection loops of rising warmed air and falling cool air can be exploited to good effect to contribute some or all of the required flow.

Occupants in buildings will feel heated air against their skin and have an immediate awareness of warmth and perceived comfort.

These advantages of air as a heating medium are also the disadvantages. The low density of air means that it loses its heat very quickly to more dense objects; raising the temperature of objects in a building via air flow can take a long time, and often objects and the surfaces of the building remain significantly cooler than the ambient air temperature. This can lead to discomfort as the warm occupants in the home will unwittingly be trying to heat the building’s surfaces radiantly, one of the reasons it’s possible to feel a “chill” even in a warm building.

The convection loops associated with air delivery ensure that the warmest area of the building is at the ceiling and the coolest is at the floor. Since occupants reside on the lower side of this balance, some heat is “wasted” by being concentrated outside the contact zone for occupants. Convection loops can also cause cool air to move against occupants in some areas of the building, causing the feeling of chilly drafts even in an air tight building.

In forced air systems with ductwork and fans, the layout must be done carefully if it is going to be efficient. Limiting the number of bends and restrictions increases flow, and proper positioning of outlets can reduce unwanted convection loops and create a relatively even distribution of heat.

Air heating systems will move a significant amount of dust and allergens as it flows. In forced air systems, inline filtration is highly recommended. For natural convection systems, an active filtration system is worth considering.

2) Hydronic Delivery

Using a fluid (typically water) to transfer heat from a source to a destination is a strategy with a long history. Water has a high capacity for absorbing and releasing heat in the range of temperatures used in buildings, and its high density means it can store a lot of heat.

Hydronic heating systems are often called “radiant” heating systems, especially when the heat is delivered to an entire floor area, but this is not an accurate description. Floor heat is conducted through feet, and a very even and useful form of convection accompanies the radiant transfer of heat.

Hydronic heat delivery can be achieved via a radiator that has a lot of surface area. Radiators can be the floor, walls and/or ceilings of the building, or purpose-built radiator systems. Water-to-air systems use a radiator inside forced air ductwork to create a hybrid system.

In all of these systems, produced heat is absorbed into the transfer fluid and moved through pipes through the action of a mechanical pump. The fluid is delivered through branch pipes to the point(s) of delivery where the heat is released, before being recirculated to the heat source again.

Hydronic heating systems will take a longer time to deliver perceptible heat, as the water requires more heat input to reach a perceptible temperature change. Once delivered to the radiator, the quantity of heat in the mass of the water and radiator creates much slower release times. The mass of air (and in some systems, even people) in the building will be lower than the heated mass, and all will rapidly be warmed to the radiator’s temperature without “draining” the radiator of its stored heat, resulting in longer but less frequent cycling of the heating system compared to air systems.

The design of hydronic systems needs to account for the surface area and distribution of the radiator(s), the length of piping and head, and the temperatures required to provide comfort based on the radiator layout. Systems can be quite simple, with a single pump and just a few radiator loops, or they can be complex with multiple pumps and valves responding to individual thermostats in each radiator zone.

Heating System Design: Heat Loss Calculation

Regardless of type of heat production and means of delivery, the design of an effective heating system starts with an accurate assessment of the expected heating needs for the building. This is achieve through the completion of a heat loss calculation. Many building codes now require such a calculation, and even if it is not a legal requirement it is recommended. Oversized or undersized heating systems are not efficient, and will cost a lot more than the calculation.

There are free, simple spreadsheets that can be used for heat loss calculations. These involve gathering dimensions for wall, floor, ceiling, window and door surface areas from the building plans and assigning each its expected heat loss rate (U-value or R-value). These figures are tallied and factored with the number of degree days and minimum anticipated temperature. The results include the hourly heat loss for the coldest expected day (expressed as BTU/hr) and total yearly heat loss (in millions of BTU).

More complex and comprehensive computer modeling programs will include more variables in the calculation, giving consideration to solar gain, thermal bridging in the building enclosure, anticipated air leakage rates and occupant behaviour among other factors. The more detailed the calculation, the more useful the resulting figures for sizing heating systems.

The hourly heat loss figure determines the maximum required output of the heating system, and the total yearly heat loss helps to anticipate energy requirements and costs. Figures from a good heat loss calculation also allow the design of the building to be tweaked for maximum efficiency at the design stage, as variables can be adjusted to determine ideal levels of insulation, window size and quality and air tightness.

With the parameters established by the results of the heat loss calculation, the particulars of the system can be designed to meet these needs in the most efficient and comfortable way.

Making Better Buildings book

This content is based on the book Making Better Buildings by Chris Magwood. 

2017 Workshop Schedule

Endeavour 2017 Workshop Schedule

We are excited to present a wide-ranging workshop series for 2017. Please click on the links below to explore each workshop!

We look forward to working with you in 2017!

 

TitleStart DateInstructorAvailable Spaces
Essential Hempcrete ConstructionFebruary 25, 2017Chris Magwood1Register
Introduction To CarpentryMarch 4, 2017Jen Feigin, Shane MacInnes5Register
Residential Plumbing InspectionMarch 8, 2017Jeffrey Chalmers10Register
NEW! Tools For TeensMarch 13, 2017Jen Feigin, Shane MacInnes8Register
Introduction To Renewable EnergyMarch 25, 2017Sean Flanagan10Register
Intro To Woodworking – Make A Cutting BoardApril 8, 2017Annie Murphy7Register
Build Your Own Bee Hotel – Intro To Bees & The EnvironmentApril 16, 2017Jen Feigin, Marcy Adzich12Register
Passive House Builder TrainingApril 21, 2017Natalie Leonard15Register
Intro to Sketch-Up – 3D Drafting BasicsApril 29, 2017Shane MacInnes12Register
Water Harvesting Earth WorksMay 6, 2017Douglas Barnes12Register
Carpentry For WomenMay 13, 2017Deirdre McGahern, Jen Feigin5Register
Art of Tadelakt Plaster WorkshopMay 27, 2017Mike Henry6Register
Natural Plaster Workshop – Base Coat to FinishJune 10, 2017Chris Magwood, Jen Feigin11Register
Legal Process BCIN CourseJune 12, 2017Jeffrey Chalmers6Register
Small Buildings BCIN CourseJune 19, 2017Jeffrey Chalmers9Register
NEW! Permaculture Design CertificateJuly 10, 2017Douglas Barnes12Register
Legal Process BCIN courseSeptember 11, 2017Jeffrey Chalmers12Register
HVAC House BCIN courseSeptember 18, 2017Jeffrey Chalmers12Register
Introduction To Renewable EnergySeptember 23, 2017Sean Flanagan12Register
House 2012 BCIN CourseSeptember 25, 2017Jeffrey Chalmers12Register
Part 8 On-Site Sewage Systems BCIN CourseOctober 16, 2017Jeffrey Chalmers12Register
Essential Building Science WorkshopOctober 27, 2017Jacob Deva Racusin12Register
Essential Hempcrete Construction (2)November 4, 2017Chris Magwood11Register
Essential Straw Clay ConstructionNovember 5, 2017Chris Magwood11Register
Carpentry for Women (2)November 11, 2017Deirdre McGahern, Jen Feigin8Register
Design Your Own Sustainable Home Workshop (2)November 18, 2017Chris Magwood15Register
Natural Plaster Workshop – Base Coat to Finish (2)December 2, 2017Chris Magwood, Jen Feigin12Register
TBA- Timber Framing – From Start To FinishDecember 30, 2017Register
TBA- Concrete Counter Tops- Form, Pour & Polish!December 30, 2017Register
TBA- Adobe Pizza OvenDecember 30, 2017Register
TBA- Engineering For Alternative BuildingsDecember 30, 2017Register
TBA-Rocket Mass HeaterDecember 30, 2017Register

Rammed Earth Construction Basics

Rammed earth construction basics

How does rammed earth construction rate? This introduction to rammed earth construction is from the book Making Better Buildings: A Comparative Guide to Sustainable Construction for Homeowners and Contractors, by Chris Magwood from the Endeavour Centre. The book gives unbiased information about all the different sustainable building material options.

Applications for rammed earth wall systems

  • Load-bearing wall systems
  • Interior walls
  • Built-in furniture, benches
  • Decorative elements

Basic materials

  • Earth
  • Stabilizer (cement or lime where required)
  • Insulation (where required)
  • Water-resistant finish (where required)

Control layers

Water control  — The finished rammed earth is typically the water control layer. It is possible to use vapor-permeable, water-resistant finishes on the rammed earth surface or to include water-resistant additives in the earth mix before ramming. Additional cladding over the rammed earth is feasible but rarely done.

Air and vapor control — Solid, continuous and dense, rammed earth is an effective air and vapor control layer.

Thermal control — A rammed earth wall requires an additional thermal control layer in hot or cold climates (see Thermal Mass vs. Insulation sidebar). This layer can be on the interior, exterior or center of the wall, and is typically a rigid insulation.

How rammed earth construction works

A lightly moistened earth mix with a relatively low clay content (10%–30% is common) is placed into forms in lifts, then tamped heavily to achieve a desired level of compaction. The soil mix varies by region and builder, but it is common to “stabilize” the mix with a small amount (3%–9%) of portland cement or other hydraulic binder.

The walls are built up in continuous lifts to full height. Often they are built in sections, so that formwork is not needed continuously around the building.

Window and door openings are usually created using a wooden “volume displacement box” or VDB. These VDBs hold the place of the window or door as tamping occurs around them. Once the wall is complete the VDB is removed, leaving a well-formed opening in the wall.

For large openings, lintels of wood, concrete or steel can be used above the opening; these are often buried in the rammed earth so they cannot be seen in the finished wall.

Electrical wiring and switch boxes (or conduits to receive them) are placed in the formwork before adding earth and tamping, and are formed right into the wall. Surface mounting after construction is also possible.

At the top of a rammed earth wall is a bond beam made of poured concrete, wood or steel. The beam is fastened to the top of the wall to provide a continuous attachment point for a roof. The method of fastening will depend on expected wind and seismic loads.

In hot or cold climates, insulation is part of a rammed earth wall system. The insulation can be a continuous wrap on the interior or exterior of the wall, but more commonly it is centered in the wall. Types of insulation used will vary with climate, availability, compressive strength and environmental factors.

Rammed earth walls are usually left exposed to provide the finished surface. A variety of sealants can be used on the raw earth to leave it visible but add protection from water. Plasters and others sidings are rarely used but are possible finishes.

Tips for successful rammed earth walls

  1. Formwork is the key to building with rammed earth, and the better the formwork the faster and more accurate the construction. Forms must be able to withstand the considerable forces of ramming the earth within and be able to be assembled and disassembled with a minimum of effort. Formwork that is reusable can help keep costs down. Check with experienced builders to see what formwork systems are being used successfully.
  2. Soils used for rammed earth must be very well mixed and not too wet. An even distribution of clay and any additional binders (cement, slag, lime, fly ash) is crucial to final wall strength. Rammed earth mixes do not benefit from the plasticity that water adds, and require plenty of mechanical mixing to achieve best results instead.
  3. Test potential soils before using. The makeup of the soil is critical to the performance of the wall. A lot of soil is required to make a rammed earth wall, and changes in its composition will mean that mixes may need to change too. Compact samples of the earth and use reliable sources to determine whether or not you will need stabilizers, and which ones are most appropriate for the soil type.
  4. Plan mechanical systems and wall openings carefully, as modifying rammed earth walls is time-consuming. If services are to be run within the walls, consider using conduit so that you can make changes and repairs without opening the wall.
  5. Avoid finishes that will reduce or eliminate the permeability of the rammed earth wall.
  6. If you are building your own home, consider buying the equipment you will need to dig, mix and tamp the earth. It can be much less costly to buy used equipment and re-sell it at the end of a project than to rent it for a long period of time.

        Pros and cons of rammed earth construction

Environmental impacts

Harvesting — Negligible to Moderate. Site soil can be harvested with negligible impacts. Amending materials like sand and cement have low to moderate impacts including habitat destruction and water contamination from quarrying.

Steel for reinforcing bar is extracted in a high-impact manner, with effects including habitat destruction and ground water contamination.

Manufacturing — Negligible to Moderate. Soil can be extracted and processed with negligible to low impacts.

Portland cement, if used, is fired at extremely high temperatures and has high impacts including fossil fuel use, air and water pollution and greenhouse gas emissions.

Steel reinforcement bar is made in a high-heat process that uses a lot of fossil fuel, and has impacts that include air and water pollution.

Transportation — Negligible to Moderate.

Sample building uses 79,410 – 105,666 kg of rammed earth:

74.6 – 99.3 MJ per km by 35 ton truck

Soil, cement and steel are heavy materials, and accrue significant impacts proportional to distance traveled.

Installation — Negligible to Moderate. The process of ramming the soil mixture can be done manually with negligible impact. More often, hydraulic machinery is used, with moderate impacts depending on power source.

Embodied carbon & energy of rammed earth construction:

rammed earth construction embodied carbon

Waste from rammed earth construction: Low

Biodegradable/Compostable — All leftover earth materials.

Recyclable — Metal reinforcement bar.

Landfill — Manufactured insulation offcuts, cement bags.

Energy efficiency of rammed earth: Low to High

A rammed earth wall has a lot of thermal mass and can easily be an airtight wall system, but it has no inherent insulation value (see Thermal Mass vs. Insulation sidebar). The overall energy efficiency of a rammed earth wall system will depend on the insulation strategy. Insulation can be placed on either the interior or exterior of the wall or a double wythe system can have insulation in the middle of the wall.

Insulation on either side of the wall will force a builder to create a finished surface over the insulation, which adds cost and complexity to the wall system and isolates all of the available thermal mass on one side or the other. Core insulation is more effective and leaves the rammed earth as the finish on both sides, but complicates the forming and tamping process and limits choice of insulation to materials that can resist the compressive forces of the tamping process.

Material costs of rammed earth construction: Negligible to Moderate

Components for good rammed earth may be sourced on site at negligible cost, but pre-mixed versions with Portland cement stabilizers may be moderately expensive. The addition of rigid foam insulation between two wythes of rammed earth will raise costs considerably.

Labor input of rammed earth construction: High to Very High

Rammed earth construction is labor intensive. The use of machinery can reduce the amount of labor involved in excavating, mixing and tamping earth, but even machine time can be extensive. Building, erecting and disassembling formwork takes a lot of time regardless of tamping method. However, when used as the finished wall surface, a rammed earth wall eliminates the need for steps often required to sheath and finish other walls.

Skill level required for rammed earth construction: Moderate to High

Mixing and tamping soil does not require prior experience, but the creation and use of formwork does, as does the operation of excavation and dirt-moving machinery. A first-time builder will want some training or experience prior to undertaking a major rammed earth project.

Sourcing/availability of rammed earth materials: Easy to Moderate

Soils suitable for rammed earth construction are widely available, as are the ingredients for amending soils that are not inherently suitable. The equipment used for excavating and tamping earth is common to other more conventional construction activities and should be easy to source.

Insulation materials will vary in availability depending on type and location.

Durability of rammed earth construction: Moderate to High

Rammed earth buildings have a long history in many parts of the world, with some examples lasting well over a thousand years. Erosion and/or spalling caused by excessive wetting are the main causes of failure. Creating adequate roof overhangs and site drainage can control this. Water repellents are sometimes mixed into the rammed earth or applied over exposed surfaces. These must not affect the strength of the mix or overly reduce permeability. Plasters and other forms of siding can also prevent moisture damage.

Rammed earth, like all soil-based construction types, can be repaired quite easily if damaged, by the addition of new soil mix.

Code compliance of rammed earth construction

Rammed earth construction is an accepted solution in some building codes, in regions where the technique has historical precedent. A good deal of testing and modeling of rammed earth walls has been done around the world, and the available data is usually sufficient to justify the use of rammed earth as a load-bearing wall for one- and two-story structures. A structural engineer may be needed to approve drawings to obtain a permit.

Indoor air quality of rammed earth construction: High

Uncontaminated earth is generally agreed to have no inherently dangerous elements and is consistent with the aims of high indoor air quality.

Soil contamination, from natural sources like radon or synthetic sources like petrochemicals, is possible, and it is wise to inspect and/or test soils carefully before using them to build a house.

Future development of rammed earth construction

Code development for rammed earth is moving forward in several countries, including the US and Australia. Widespread code acceptance is likely to encourage more rammed earth construction.

As the basics of rammed earth construction have remained the same for thousands of years, revolutionary developments in technique are unlikely. However, processes to reduce labor input for formwork and soil mixing and tamping are likely to be streamlined, making the system more affordable.

How does rammed earth construction rate?

rammed earth construction

 

Resources for rammed earth construction

Walker, Peter. Rammed Earth: Design and Construction Guidelines. Watford, UK: BRE hop, 2005. Print.

Easton, David. The Rammed Earth House. White River Junction, VT: Chelsea Green, 1996. Print.

Minke, Gernot. Earth Construction Handbook: The Building Material Earth in Modern Architecture. Southampton, UK: WIT, 2000. Print.

Rael, Ronald. Earth Architecture. New York: Princeton Architectural Press, 2009. Print.

Morton, Tom. Earth Masonry: Design and Construction Guidelines. Bracknell, UK: IHS BRE, 2008. Print.

Jaquin, Paul, and Charles Augarde. Earth Building: History, Science and Conservation. Bracknell, UK: IHS BRE, 2012. Print.

Keefe, Laurence. Earth Building: Methods and Materials, Repair and Conservation. London: Taylor & Francis, 2005. Print.

McHenry, Paul Graham. Adobe and Rammed Earth Buildings: Design and Construction. Tucson, AZ: University of Arizona, 1989. Print.

 

Essential Sustainable Home Design

FREE CHAPTER OF NEW BOOK! Essential Sustainable Home Design is the latest book by Endeavour’s Chris Magwood. Get a sneak peak at the book that’s based on our popular Design Your Own Sustainable Home workshop.

Many people dream of building a beautiful, environmentally friendly home. But until now there has been no systematic guide to help potential builders work through the complete process of imagining, planning, designing, and building their ideal, sustainable home.

Essential Sustainable Home Design walks potential homebuilders through the process using key concepts, principles, and a project matrix that will guide the house to successful completion.

The book includes:

  • How to clarify your ideas and create a practical pathway to achieving your dream
  • A criteria matrix to guide design, material, and systems decisions
  • Creating a strong, integrated design team and working with professionals and code officials to keep the project on track from start to finish
  • Key building science concepts that make for a high-performance, durable building
  • Primer on building logistics, material sourcing, and protocols to ensure that the initial vision for the project comes to fruition
  • One-page summaries and ratings of popular sustainable building materials and system options.

Ideal for owner-builders and sustainable building contractors working with clients aiming to design and build a sustainable home.

Download a PDF of the Building Permits chapter.

ESSENTIAL SUSTAINABLE HOME DESIGN IS AVAILABLE FOR PRE-ORDER NOW!

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