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Technology

Photograph of CHIP's Mitsubishi mini-split HVAC unit.

Overview

CHIP's life support systems employ a deep understanding of fundamental principles, system modeling and analysis to achieve an affordable net zero goal. This implies a balance between energy efficiency, generation, and overall system cost, while maintaining the occupant comfort as a primary goal. Thoughtful user interface design allows the system to be easily tuned to Southern California or any other climate, while exposing energy consequences of the occupant's choices.

Air Conditioning/DHW

CHIP's energy-efficient mechanical core comes from taking a holistic view of the systems involved. In its cooling mode, an HVAC system extracts heat from the air in the house, while a domestic hot water (DHW) system heats cold water that comes in from the municipal supply. By using the waste heat from air conditioning to heat hot water, we can realize significant energy savings. A thermal storage tank stores the heat from the AC condenser until it is needed to heat water, and a second heat pump ensures that the DHW is always hot enough, even when the AC isn't being used.

Custom control software automatically adjusts the setpoints on the HVAC system based on weather conditions, and predicted demand in order to keep CHIP energy efficient without sacrificing comfort.

Diagram showing the parts of CHIP's combined air conditioning and hot water system and how they relate to each other.

Ventilation

The indoor HVAC fan coil units circulate and filter air within the house using anti-odor and anti-allergen filters. The energy recovery ventilator (ERV) provides a constant supply of fresh air to meet ASHRAE recommendations while maintaining the conditioned state of the interior space. This represents a significant improvement in both comfort and energy efficiency over a poorly sealed home, in which infiltration of unconditioned air into the interior space is the primary form of fresh air intake.

The whole-house fan can perform an air change in the entire house in under half an hour to clear contaminants and introduce fresh air; this is particularly useful in California, where the whole-house fan can be used to take advantage of the large diurnal temperature variations to cool the house in the late afternoon.

Natural ventilation is promoted by the sloped floor plan. Cold air is introduced through the low south window while hot air escapes through the elevated north window.

Diagram illustrating how CHIP's elevated north end can help draw air through the house, taking advantage of hot air's tendency to rise to help cool the house.
Close up photo of a PEX sprinkler fitting

Water Systems

CHIP's supply plumbing uses PEX (cross-linked polyethylene) tubing, which is reliable, corrosion-resistant, leak-proof, lower maintenance, quieter during operation, and cheaper to install than typical CPVC or copper water supply pipes. CHIP's fire suppression system is connected to the primary PEX supply line in a loop, obviating the need for yearly drainage of the fire suppression system.

A dual-flush toilet (0.8/1.28 gpf) and WaterSense-approved low-flow faucets and showerheads are used throughout the house to minimize water consumption without sacrificing comfort.

Greywater/Rainwater

The rainwater collection system uses the downward slope of the south-facing roof to direct water onto the south deck where it filters through the deck and into a storage tank. A small pump directs the water to drip emitters that irrigate plants. The pump is activated based on weather forecast data. Laundry greywater is also used to water plants, however it is handled separately from rainwater and is not stored for later use because of the stringent code requirements in California. Laundry generates a substantial amount of greywater irrigation at almost no cost to the user.

Diagram illustrating rainwater running down CHIP's roof into the storage tank, and then being delivered to plants as needed as determined by a timer and by the weather.
Picture of PV panels

PV

CHIP generates its own electricity from a photovoltaic (PV) solar power system using panels from Hanwha Solar. Extensive modeling of PV panels and analysis of weather patterns show that CHIP's 7.8 kW system consistently achieves net-zero-energy, meaning CHIP's owners will never have to pay an electrical bill. CHIP's roof also has enough room for several additional PV panels, so it can be easily adapted to other environments or additional occupants.

The system also employs innovative power tracking systems at each module, which lets the system operate in partial shade without hinderance. It also allows us to see how much energy each panel produces at any given time.

Diagram illustrating photovoltaic system.  PV panels output power through Tigo Module Maximizers, which are connected together.  From there, power feeds into the inverter, and then back to plug loads in the home or into the grid.
Picture of an LED lighting fixture.  The fixture is stainless steel and has three LEDs providing a yellow-white light.

Electrical/Lighting

The electrical system of the house is highlighted by the prevalent use of daylighting and judicious selection of efficient and affordable consumer electronics and appliances. The lighting strategy takes maximum advantage of daylighting while satisfying nighttime lighting demands using efficient LED's and CFL's. The wide range of consumer electronics and appliances selection not only covers basic amenities, such as refrigeration and laundry washing, but offers homeowners the latest technology in home entertainment.

Marketing photo of the eGauge main controller

Energy Monitoring

We are using eGauge to constantly monitor the electricity use in our home. This information is logged and presented to the homeowner online and in CHIP's iPad app. Having this information readily available helps a homeowner to understand how their home uses energy and helps them to locate parts of their lifestyle that use excessive amounts of energy.

Close up photograph of the circuit board inside CHIP's Control4

Smart Home features

The lights, home theater, shades, and mechanical systems of CHIP are connected to a home automation system from Control4. This means that certain tasks can be done automatically, like turning off the lights when no one is home, lowering the projector screen automatically when a new movie is inserted in the Blu-ray player, or only running the drip irrigation system when the weather is dry (though that's almost all the time here in southern California).

The system is also programmed to:

  • Slowly turn on your lights in the morning to wake you more naturally
  • Turn your devices on when you sit in certain chairs
  • Close the blinds for you when it is bright and you want to watch the projector
  • Close the shades when sunlight is shining into your home, heating it up

And because the controller is an internet capable device, you can access all of the functionality remotely too. For example, when you get to the airport and realize you forgot to turn off your bathroom light, you can pull out your smartphone and check that CHIP remembered to turn them off for you, and then turn off the air conditioner to save energy for good measure. When you come back, you can connect in and turn the AC back on a few hours before you arrive home again so that things will be comfortable by the time you do.

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Southern California Institute of Architecture Southern California Institute of Architecture California Institute of Technology California Institute of Technology Solar Decathlon U.S. Department of Energy NREL