Saturday, October 20, 2012

Build an E-House!

By Arno de Villiers B.Arch.                         
Arno Construction - Florida Certified Building Contractor CBC 1255481
phone 239-571-7585 email:  

1. Introduction

Many Florida residents are tired of the same old Mediterranean architecture. It is time for something new and refreshing and at the same time beautiful, contemporary, sustainable, high-tek and yes, affordable!
E-House #1 is my response to the increasing demand by singles, retired couples, empty nesters, etc for an affordable home that can fit on an available small lot. It is a three bedroom, two bathroom house of only 1440 square feet.


2. E stands for Efficiency

Residential design keeps moving toward high-performance sustainable building systems.  To be sustainable, a building must not only be efficient and durable but also economically viable.  New methods of enclosure have been examined that provide high thermal performance and long-term durability. They reduce material use, simplify systems and details, and potentially reduce overall initial costs of construction. 

3. Efficient Design

Educated design can make every square foot count, reducing wasted space by keeping hallways etc. to a minimum. The effective use of construction dollars calls for efficiently designed spaces and scientifically considered building envelopes that provide both security and cool economical thermal environments.


4. Energy Efficiency

Living in Florida conjures up swaying palms, swimming pools and fresh orange juice... and lots of air-conditioning.  A summer spent in Florida’s heat and humidity would be unbearable without it. Air-conditioning is an absolute necessity but also a big energy drain accounting for about 35% of all electricity used in a typical Florida house. Minimizing the loss of cool air to the exterior in summer is the first order of business in an energy efficient Florida home.

5. Steel Frame and Rain-shield Insulated Walls

The use of a structural steel frame engineered to resist 150 mph hurricane winds, plus an external panel rain-shield is preferred over the use of wood studs, plywood and OSB. The latter although considered renewable are subject to destruction by termites, moisture and rot.

Note the E-House corrugated steel "rain-shield" outside walls 
and the contrasting concrete block carport

6. High Insulation Levels

The U.S. Department of Energy has developed a list of recommended insulation levels for different climate zones. Because electric heat is relatively expensive, houses with electric resistance heat need insulation to exceed the recommended levels. Most insulation materials function by slowing the conductive flow of heat. Materials with low thermal conductivity more effectively block heat flow than materials with high thermal conductivity. The R-value of an insulation material measures its resistance to heat flow.
For Collier county in Florida, the recommended minimum R-values are: Roof = R-30, Walls = R-13, Floor = R-11. E-Houses’ unique roof and wall assemblies are carefully designed to exceed these values. Polyisocyanurate or “polyiso” is no longer produced with HCFC's, and is now the environmentally preferred rigid board insulation for above-grade applications.

7. Wide Roof Overhangs

The traditional wide roof overhangs of old-style Florida homes are seldom used these days. The assumption is that air-conditioning takes care of cooling needs. But why make the air conditioner work harder and costing more than it should? The E-House restores wide roof overhangs that aim to shade the south and west windows from solar heat gain. The large gently sloping roof is also perfect for collecting rain water for the garden or filtered for potable use.

8. Reflective Metal Roof

Another feature is the reflective light colored standing seam roof versus the popular grey, red and orange cement tiles or asphalt shingles on the “Mediterranean” home.  Even if all homes have R-30 fiberglass roof insulation, one study shows that on a day when the temperature in the attic of a standard Florida home rose to 138°F, a similarly insulated attic under a reflective metal roof reached only 100°F. (*1) 

How about trading these gas guzzlers for new hybrids? 
Note the battery closet for the PV system at the back of the carport.

9. Interior-Mounted Oversized Ducts

Oversized air-conditioning ducts, positioned within the air-conditioned space as opposed to a hot attic are used in the E-House to advantage. Tests have shown that heat transfer to the duct system can rob the air conditioner of as much as one-third of its cooling capacity during the hottest hours. Over-sizing the ducts allows high air flow and low friction loss (previously shown to provide as much as a 12% improvement in cooling efficiency at essentially no extra cost).

10. Solar Control Window Film

Sun control window film can account for up to one-fifth of the energy savings for cooling, rejecting up to 60% of the heat coming through the glass. They can be carefully selected for both appearance and thermal effectiveness. They transmit much of the light in the visible portion of the solar spectrum, but limit transmission in the infrared and ultraviolet portions which causes overheating and fading of interior materials.

11. Photo Voltaic Solar Panel System (PV)

Most installations in the U.S. are grid-tied, meaning the house can draw power from either the utility grid or its PV array. When the PV cells aren't producing enough power, the grid makes up the difference. When the array makes more than the house consumes, the electricity flows into the grid.
Off-grid systems, which require a battery bank to store power, are more expensive and more complicated and can be considered as an optional extra.
Research has shown that a home in a climate such as Florida's be engineered and built so efficiently that a relatively small Photo Voltaic system would serve the majority of its cooling needs—and even some of its daytime electrical needs and be as comfortable and appealing as the conventional model built alongside it.
A comparative study of two Florida houses was made during the very hot month of June. One house that was designed and built with these listed features, consumed only 335 kilowatt-hours (kWh) of utility-grid power for all its electrical needs. This compared to 1,839 kWh used by the unoccupied control home for air-conditioning only! The monthly power cost in the first home was only 18% of the control home’s power cost. (*1)

A PV system can be sized to provide power that would offset as much of the household load as possible. Based on the predicted load for a peak day, a 4-kW PV array (split into two sub-arrays) can be specified. One sub-array can be located on the south-facing roof, which is generally the preferred placement for a PV system. The other can be located facing west because this orientation provides more PV power during the hot afternoons, when the utility experiences its peak demand period. Reducing demand at this time of day is particularly valuable to the utility. The PV system is grid-interactive, producing DC power that is converted to AC and then fed directly into the local utility distribution system. The City of Lakeland Department of Electric and Water Utilities in Florida, which owns and operates one such PV system, allowed connection of a residential PV system to the utility grid in Florida.

12. High-Efficiency Lighting and Appliances. 

Energy Star appliances use less power and LED lighting release less heat into the home while operating, which decreases the cooling load that must be met by the air-conditioning system. The smaller appliance, lighting, and air-conditioning loads result in less PV capacity required to meet the home’s total electrical load.

13. High Efficiency Air-Conditioning and Programmable Thermostat

A programmable thermostat that is set so that the indoor temperature is allowed to increase overnight and while the house is unoccupied—decreases the number of hours per day the air conditioner operates. Running the air conditioner less reduces the total electricity consumption and lowers utility costs. The combination of efficiency features reduces the cooling loads so that a downsized air-conditioner will suffice. It has been shown that a system could be as little as half that of a typical Florida home and still perform to expectations (1).  The unit's cooling coil air flow involves using a flow hood to adjust the fan speed of the variable-speed air handler. Installers who neglect this crucial step commonly cost the system a 10% drop in actual operating efficiency.


14. Solar Hot-Water System

In Florida especially, a solar hot water system is a sensible way to heat water for showers and laundry. The solar hot-water system can supply as much as 66% of the hot water for occupant needs before power is drawn from the electrical utility company or a propane hot-water heater that can be used as a backup is activated. 

15. Geothermal Heat Pump

Florida is blessed with an enormous aquifer below it that keeps a stable temperature in the mid 70F’s all year long.  An air conditioner or geothermal heat pump would rather reject heat to 75 degree water than to 95 degree outside air or to 82 degree soil. Geothermal heat pumps work similarly to air-conditioning except that during cooling, heat from the house is discharged into the 75deg aquifer rather than the 90deg outside air. The benefits are lower energy bills, longer equipment life and no exposed condensing units or cooling towers. Design and installation has to be done by experts and can be considered an optional extra. (2)

16. Summery of E-House Features

• Light colored metal roof with large overhangs
• R-30 roof insulation
• R-13 exterior insulation over metal frame system
• Advanced solar control double-glazed windows
• Oversized, interior-mounted ducts
• High-efficiency refrigerator
• High-efficiency LED lighting
• Programmable thermostat 
• Solar hot-water system (upgrade)
• Downsized SEER 15.0, variable-speed, 2-ton air conditioner with field-verified cooling-coil air flow
• 4-kW utility-interactive PV system. (upgrade)

Contact Arno for further information.


  1. This is a very nice concept. I absolutely think this will work amazingly. Good work!

  2. Great Post.
    You share Interesting and valuable information.
    Thanks for sharing.
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