Multiple elevation changes and customized footings and pads created a series of challenging steel reinforcement and forming details. Drops in footing levels, as much as six feet, had created virtual “windows” in the foundation which generated another set of challenges during concrete placement.

The Quad-Lock Solution:

The expansive home in the Cotswolds, England, not only exceeds the UK’s Code 6 Sustainable Homes Guide, it surpasses the German ‘Passivhaus’ energy efficiency standards by over 65%! This is quite a feat, especially when you consider that the home is over 21 times bigger than the average UK home, at 1,500 sqm (16,000 sqft). The entire construction process has been documented by the home’s owner & builder, John Croft.

Quad-Lock was chosen for the basement and some of the interior walls based on the energy efficiencies and speed to construct. The 40m x 7m (131ft x 22ft) basement with a 3m (10ft) wall at the front and a 5.5m (18ft) wall at the back with a 20cm (8″) concrete core took John and his brother less than 2 days to build and pour! Quad-Lock was also used for the infinity swimming pool as well as the boat/summer house on the lower lake.

The home has no heating demands, is not connected to mains water or sewerage, uses no fossil fuels, and is lit entirely by ultra low LED lighting. The building is self-sufficient in its energy requirements by utilizing an array of discretely positioned PV panels, which supply more electricity than the house uses. The surplus is fed back into the grid, generating an estimated income of £3,500/year (US$5,600/year).

See videos of the basement construction and why John chose Insulated Concrete Forms for his eco-friendly house.

Here’s a look at the components:

1. Design and Orientation: Roof overhangs, window size and placement, and overall home shape have a major impact. Consider the direction of prevailing winds and how to manage solar gain. If you will be using solar collectors, ensure that a portion of the roof faces true south. The placement of porches, garages, trees,and nearby buildings also have an effect.  

 

2. Insulate and Seal the Building Envelope: Most of a home’s energy is spent heating and cooling the interior. Minimizing heating and cooling requirements is the most important step in building a ZEH.
   1. High R-Value Insulation: For a zero energy home, use high R-value insulation that provides a continuous, unbroken layer around the building envelope. Remember to insulate under the slab as well. Use a high-insulation, tightly-sealed roof system, such as Quad-Deck or closed cell spray foam. Seal all holes, cracks, and penetrations through the floor, walls, and ceiling to unconditioned spaces.
   2. Concrete Thermal Mass: Build exterior walls and floors with concrete. Concrete will moderate temperature swings, and can even dampen seasonal fluctuations by “spreading” the constant ground temperature from the footings throughout the home.
   3. Airtight Construction: ICFs will ensure airtight walls. Ensure that all windows and doors are tight and meet the required air-leakage standards. The roof and/or ceiling needs special attention, as do the kitchen and bathrooms, to make sure they have adequate ventilation but still maintain energy efficiency.
   4. Windows and Doors: Use triple glazed windows and well insulated or double external doors. The passive gain of incoming solar heat through the windows will cover close to 40% of the heat losses, if
      all guidelines are followed. Skylights can decrease artificial lighting requirements, but use a high-quality, double glazed product.

 

3. Increase Heating and Cooling Efficiency: The heating and cooling systems need to be carefully matched to the high-efficiency building envelope. Standard-sized equipment will “short-cycle,” turning on and off so frequently that it will negate any energy savings. Buying properly sized equipment will ensure maximum
   efficiency. Another benefit: smaller equipment will cost less. 
   1. Buy as high-efficiency equipment as affordable.
   2. Take Advantage of Earth Temperature: Install a geothermal pump or/and a ground-air heat exchanger where space and cost conditions permit.
   3. Radiant Floor Heating: Radiant floor heating (e.g. with Quad-Deck) provides warmth
      in a pattern that mimics the body, improving comfort. It heats evenly without drafts and uses far less energy than conventional systems. It also reduces noise and allows room by room zoning.
   4. Optimize Ducting: Design the supply and return ducts appropriately and seal tightly using approved tapes or mastic. Run ducting in conditioned space only.
   5. Alternate Cooling Methods: Where appropriate, consider alternative cooling systems such as ventilation only or evaporative coolers.

 

4. Decrease Other Energy Requirements: Decrease energy needs as much as possible throughout the home.
   1. Install efficient lighting: Use compact fluorescent bulbs where possible, and consider installing permanent fluorescent fixtures throughout the home.
   2. Install efficient appliances: Use the most energy efficient models available. Focus especially on the refrigerator, dishwasher, and laundry appliances, as they use the most energy. Look for the Energy
      Star label to help make decisions.
   3. Tankless Water Heaters: Use tankless water heaters, especially if the home will not be constantly occupied. Low-flow fixtures in showers and faucets will also decrease hot water demands.
   4. Turn off lights, computers, and appliances when not in use:
      The homeowner has the most significant impact on the actual performance of the ZEH. Programmable thermostats and photo-sensitive outdoor light fixtures will do some of this automatically. Simple things such as turning off lights when leaving a room or closing doors when performing even quick tasks outdoors can eliminate “wasted” energy.

 

5. Install Energy Generation Equipment such as solar panels

Remember the concept of “system engineering.” Often, low-efficiency components can be compensated for in other areas. For instance a house with many doors may require significant improvement in other components, while a well designed, moderately-sized house may find standard doors sufficient.

Zero Energy Quad-Lock Home in Leverett, MA:

Reprinted & modified with permission from ICF Builder Magazine: April/May 2008

For Quad-Lock walls with nominal concrete thickness of 8″ or less, the standard footing width of 16″ is usually sufficient but check with your local building department. Walls 10″ and thicker are usually engineered, so the engineer will specify footing widths.

In the United States the following code sections set out the requirements for Quad-Lock wall footings

In Canada the following code sections set out the requirements for Quad-Lock wall footings:

When placing rebar dowels, take into account the panel thicknesses.

Building Tips: When pouring your footings:

1. Level them to within a tolerance of ¼”.

2. Trowel footings smooth to prevent rough surfaces.

3. Ensure that all steps are 12″ or any multiple thereof to match the height of the panel.

The few extra minutes spent ensuring your footings are level and smooth will save hours in setting up the wall!

Stepped Footing Detail

Note: Steps heights should be designed in 12″ increments to suit the system or any multiple thereof. If the steps are not in 12″ increments, cut the panels to fit the footing steps.