The Design.
The best design for the structure, (to ensure compatibility for design, market acceptance as well as accurate test results), is to be a small home complete with basement, targeting the low to mid income bracket.
Materials.
Advanced Materials to be used in the structure include existing products such as ICF wall system, basement insulated slab on grade system, composite concrete intermediate floor system, High performance, dual glazed, low-E and argon filled windows, with exterior stucco and cultured stone systems.
New technologies developed include; A hybrid ICF composite concrete cast in place roof forming system utilizing both Formtech and Speedfloor components. A simplified radiant in floor heating system. Earth coupled geothermal water to water hydronic heating/cooling system, utilizing passive soils heat transfer methods to reduce loop lengths, and engineered soils to increase performance. An advanced air separator cleaning unit and fresh air energy recovery ventilation system complete with an integral mid volume air conditioning system.
New methods of installation including external vibration methods utilizing new technology. More efficient design and detailing methods. Introduction of new installation methods, which simplify and demystify the processes involved in the construction. Multi function or combined construction tasking, which combine two or more tasks into one. Lowered experience and knowledge requirements through efficient material selection, management practices, design, detailing, and scheduling.
Criteria included in design and developed products and/or techniques
Over the last years we have accumulated information and research into the needs of the building market place, and determined that the following base criteria for all products would have to be addressed within the design and/or construction of the building.
1. Cost. Overall, the cost of materials and/or labor would have to ensure that the current construction methods associated with ICF construction would have to decrease the total cost of the building by the offset cost of utilizing these types of products installed to current standards.
2. Efficiency. The material and labor components must comply with efficiency in design to reduce construction time, and reduce material requirements by a undetermined acceptable level. Material components should perform two or more construction or building functions per item, or combine several aspects required into the design, such as stay in place formwork.
3. Methods of construction. The methods of construction must simplify the construction process, allowing low skill labor to be utilized effectively.
4. Quality of construction. The Quality of the building must be increased to meet the new challenges of a modern world including Longevity, durability, strength, esthetics, operation, form and function.
5. Compatibility. The building must be constructed in such a matter as to be identical in form and function with current residential structures.
6. Versatility. Any normal residential structure must be able to be designed and built with the systems and methods, to ensure compliance with current designs in the construction industry.
7. Needs and shortfalls. The building has to address most, if not all, of the current needs and existing shortfalls in residential dwellings.
8. energy-efficient. Energy requirements should meet or exceed, even the highest standards of current construction materials and methods.
9. Environmental Friendly. The materials and methods should address as many environmental considerations as possible, including waste, energy required for production of materials, and energy required for construction. Low environmental impact products and methods of construction would be a must.
10. Manufacturing capability. All products and existing labor markets must be able to be easily adapted to meet the needs for construction of buildings of this type.
All materials and components as well as the manufacturers have been selected based on the product's ability in speed, durability, workability, quality, strength, warranties and market acceptance from existing raw materials and/or processes.
Heat loss.
Component factors
Roof effectiveness.
Existing energy efficiencies for ICF wall systems rate about 30% more effective in overall heating and cooling when combined with current standards of wood truss roof installation and slab on grade basement installations. Knowing that the current energy loss's in a heating climate for walls in residential structures is about 23% of the overall loss of a home, and the roof representing about 42% of the overall heat loss, I am assuming the following: 42% (total roof loss on a normal home)/ 23% (total wall loss on normal home)X 30% (the known effectiveness of ICF walls only on a home) should in theory increase the effectiveness of the above slab thermal envelope by about 54.78%.
This assuming comparative R-value increases, combined with reduced air infiltration and thermal conductance characteristic differences associated with ICF construction.
Below grade and under Slab effectiveness.
Although smaller, below grade and under slab loss's do count in the overall building heat loss, and typically represent about 7% of the total heat loss on the building. This can be reduced substantially through the use of effective drainage of ground water, the inclusion of foil covered Expanded Polystyrene insulation to isolate the slab from the ground as well as ICF construction for the basement walls. By including 4" of EPS foam, a reflective layer of foil, and effective subsurface drainage, we can increase the efficiency of slab on grades and below grade areas by about 67% over the current accepted standard of 6 mil polyethylene sheets only. Assuming these numbers to be accurate, we can include the following, 7% (total heat loss through the sub structure area) X 67% (effective increase in thermal performance of the slab) = 4.69% (total added savings overall to the heat loss characteristics). Adding this to the above slab thermal envelope effectiveness, we now have a building which is 59.47% more effective than standard construction methods.
Window/Door factors.
Outside issues, such as windows and doors have an overall heat loss characteristic of about 17% on the total home, through infiltration, loss/gain and conductance. Primarily by incorporating a higher quality window, built with lower air infiltration rates. Less thermal conductance and the inclusion of affordable low E glass with Argon gas between two thermal panes. Existing studies and tests prove that these types of windows and doors increase the thermal performance of such units by about 30%. On a home, this a relatively high factor outside of standard construction, due to the extensive use of window area in design. We will be assuming normal use of about 15% of wall area. Assuming these numbers to be correct, we can, in theory say that 17% (heat loss through windows and doors in standard construction) X 30% (increase in performance of higher quality windows) = 5.10% (savings in heat loss for new structure). Adding this to total thermal envelope effectiveness, we now have a building which is 64.57% more effective than standard construction methods.
Overall factors.
Standard Ventilation factors
Ventilation factors of.3 air changes per hour are a standard code requirement. Current standards of construction achieve this through the use of exhaust fans or air changers. The proposed standard will include a high-efficiency, dual core system from NuTech, which operates to effectively supply.3 air changes per hour with 87% effective heat recovery from the exhaust air. Knowing that the mechanical ventilation accounts for about 8.5% of the total loss to the building, we can effectively assume the following. 8.5% (mechanical ventilation loss to building) X 87% (effectiveness of Heat Recovery Ventilation unit used) = 7.39% (increase of performance for air exchange. Adding this to the above effectiveness, we now have a building which is 71.96% more effective than standard construction methods.
Radiant heating.
Further energy savings, in the heating climate which would have a significant impact on the study, include Radiant Heating and high-efficiency boilers, through a hydronic installation, which is supported by existing studies to increase energy efficiencies about 20% overall. The base theory to support this the effectiveness of radiant heat over convected or conducted heat transfer to occupants of buildings. Taking this factor into account in a ratio for normal construction and the proposed ICF shell, 20% (representing standard construction methods effective reduction in heat requirements) X (100% - 71.96%) = 28.04% (representing remaining energy required by incorporating ICF envelope) = a further 5.61% in total energy savings through the use of radiant technology. This equates to 77.57% total energy savings included in the calculations.
Thermal Mass and Heat Storage
By utilizing a compromise, the home is designed to take advantage of off-peak heating through the use of concrete in the structure. Effectively, the building would be utilizing the off-peak hours to store heat energy in the thermal mass of the concrete floors, for daytime use. This to be achieved simply through the use of programmable thermostats, which would store heat in the concrete slabs during the early morning hours. The overall effectiveness is currently undetermined.
Geothermal Applications.
Through the use of passive solar collectors, installed below the roof shingles, and integral with the ICF roof assembly, on warmer winter days, solar heated water would be used in a closed parallel loop to increase the geothermal bed temperatures, thereby effectively storing heat for later use in the ground. During summer months, the same parallel loop, will utilize rain water and cooler nighttime temperatures, in an effort to reduce ground temperatures. Over the loops, a new product, "InsulTarp" will be installed to prevent excessive loss's to the earth surface. This being studied in an effort to reduce trench depths, and loop lengths from the current standard, as well as increase efficiency of the geothermal heat pump system. Overall effectiveness is currently undetermined.
Geothermal units operate much more efficiently as the load decreases on the unit. When any fluid material, (including air which acts in the same way as a fluid) requires a large delta T temperature increase, (the difference between the return fluid temperature and the supplied fluid temperature) a geothermal heat pump has to work very hard to pump enough heat to supply the demand, so the efficiency of the unit drops. This called the COP or "coefficient of performance". Most geothermal units operate with a heating COP of about 3. What the COP represents is the comparison of the overall energy output from the unit, over the energy input to the unit. A COP rating of 3, means that for every 1 unit of energy or "watt" we put into the geothermal heat pump, we get 3 watts of heat out of it.
Now here is where it changes when we combine it with ultra efficient structures, hydronic in floor heating and thermal mass.
The much lower heat loss of the building, means a lower Btu output per square foot of floor area, In the case of some of our research structures, this equates to about 10-13 BTU per square foot in areas such as Michigan USA and Ontario Canada. Now, water entering the radiant system of a concrete floor, needs only be 76 degrees F to maintain a 71 degree F temperature for the occupants. This means that the radiant system only needs to supply a 6 degree temperature rise. This means that the coupled geothermal system now only needs to combat a heat pressure difference (for lack of a better word) of only 5 degrees F instead of a normal 50 degree rise for non concrete, radiant systems. Less temperature difference means more efficiency as the geothermal system works less, to produce more. An easier way to look at is to think of water, in which much higher volumes can be moved a small vertical distance with the same amount of energy, as compared to a large vertical distance. More water per energy unit can be moved, ergo a geothermal system can move more heat per energy unit. COP ratings up to 10 can be achieved.
This means that by building with concrete, and incorporating good design and material selections, we can extend the efficiency of geothermal heat pump systems to gain efficiencies 2 to 3 times that of existing geothermal pump capabilities.
Strength and durability.
Strength.
As the entire shell, including all interior structural components consist of steel reinforced concrete, known to be much stronger and more resistant to active loading conditions. Typically, the components used have proven, through existing engineering, testing and analysis to far outperform standard construction methods when subjected to dynamic loads suffered from earthquakes, tornadoes, projectiles etc. Due to the decreased risk of material failure, the occupants can enjoy a safe environment, and the structure will unlikely suffer damage in the event of such natural or mechanical damages, which other structures are likely to fail at.
Used independently, each system suffers from weak connections, such as the ICF wall with a truss roof, in which the roof becomes separated from the structure due to uplift, exposing the interior. Although this test model does not incorporate a product line of windows and doors, designed to withstand these types of occurrences, they are currently being manufactured. The hope is that one day we may be able to see the results from this type of construction, when including windows and doors with comparatively high strength ratings. This decision was made upon evaluation of the location in which this home was to be built, in which it would be impractical to include. Future studies of this technology should be incorporated in a coastal structure in the state of Florida, for a more accurate investigation into these types of components.
It is suggested that the ICF walls, in existence today are about 10 times stronger than standard wood frame construction methods, it may be safe to assume, that the roof system may now have that same capability.
Durability.
All of the buildings structural components are of concrete and steel. It is known that reinforced concrete is truly capable of spanning several centuries. Although it is not known as as to the overall life expectancy of concrete, many researchers have suggested periods in excess of 5,000 years. The secondary insulating component, Expanded Polystyrene, in a non-degradable plastic component, in which it is expected to last several hundred if not thousands of years, if suitably protected from Ultra Violet breakdown. As all of the EPS foam which is in the building is covered and protected from both this and mechanical damage, we can safely assume that the life of the structure would be in excess of 100 years. Potentially it could be equivalent to that of the concrete, which is expected to be several thousand.
The exterior stucco and stone coverings are highly durable. Utilizing Acrylic stucco compounds, these face coverings are almost impervious to degradation and breakdown, although they may be subject to mechanical damage, as they are exposed. However, these types of finish materials are easily repaired or replaced, and can be maintained with much lower cost/year ratios than wood, vinyl or aluminum. By replacing the shingles with long-lasting Acrylic stuccos, which are also highly resistant to the effects of acid rain or frost action, we can extend the life of the roof finishes well beyond those of standard asphalt shingles. The stuccos longevity is further enhanced as the ICF base construction on which it is applied is not only an ideal substrate, however it is dimensionally stable during temperature and humidity shifts.
Mechanical Considerations.
Although the strengths of the mechanical components are relatively unimportant, durability issues such as usable life span are reflective primarily of the wear and tear of the components. These units are expected to last a relatively short duration, as compared to the building itself, and actually should be replaced periodically as newer and more efficient units or means become available. However, current technology has expanded to include such items as Heat Recover Ventilators, Air Cleaners, high-efficiency boiler systems, and radiant heating systems which are both energy-efficient as well as cost-effective to install and operate. Most importantly, they systems need to be de-mystified and standardized sufficiently to not only operate properly, however allow for less complicated installation methods and materials, and make the technologies easier for the public to access.
Future Development.
This initial structure will utilize components which are readily available in the marketplace to achieve the basic structure and mechanical considerations, through modification of such products or methods. It is forecasted that this structure will cost 14.6% more than an equivalent structure built to code standards for wood frame construction. Due to the costs associated with prototype manufacturing for single project purposes of some components, this forecasted shortfall should easily be reduced. The projected forecast, once all manufacturing and standardization is in place for the products and methods of installation, is projected to be at or below the cost of wood frame code construction.
The benefits associated with this type of building should not be compromised as a result. We are expecting that as products and people become more readily available, that cost competitiveness will reduce the prototype buildings construction costs sufficiently. Market acceptance should be relatively good, as there are no detracting features or concerns associated with efficient buildings such as dome structures or plastic buildings. The final product will present itself esthetically and functionally, identical to current residential structures.
