Construction
Light-Gauge Steel
LuminOCity is built entirely out of light-gauge steel (LGS) framing using the FRAMECAD building system. FRAMECAD states that light-gauge steel is a combination of raw steel, iron ore, steel scrap, and carbon in a Basic Oxygen Furnace, creating molten steel that is then zinc-coated through galvanization, and bent into shape through a heat-free roll-forming machine. This process is a method that curbs carbon emissions within the industry.
FrameCAD
The FRAMECAD building system integrates computer-aided design (CAD) and engineering software tailored to output quick and accurate fully-engineered designs through cold-formed steel (CFS) printing. The design can be either imported or drafted into the software where precise engineering calculations are completed, as local CFS building codes are incorporated into the system, and be output directly to a machine for fabrication. This reduces engineering costs and prefabrication errors.
Traditional construction methods have been outpaced by the demands imposed by rapid urbanization. Within the United States as of December 2022, California was the most urban, with 94.2% of its population residing within urban areas. A growth in cities calls for a demand in construction, where new structures must be built and existing structures must expand.
FRAMECAD offers distinct advantages over other building methods as it was designed to endure rapid construction. FRAMECAD claims in “The Future of Construction” that the machine running at optimized conditions can “produce frames at 2,296 LinFt/hour with a topline speed in excess of 9,020 LinFt/hour”. Consistent quick-printing alongside light-weight “pre-cut, formed, punched, numbered, and labeled” steel parts allows builders to efficiently carry and assemble pieces. Additionally, welding or cutting is not required as frames print with exact measurements, resulting in 1% waste and reduced labor costs. Even complex framing members can be assembled with beginner level experience and minimal tools, creating construction opportunities for a wider population.
FRAMECAD emphasizes that structures can be easily built off-site and transported on-site. With prefabricated pieces and lightweight steel, FRAMECAD enables structures like LuminOCity to be efficiently assembled and transported as an off-site modular home.
Thermally Efficient and Resilient Building Envelope
The building Envelope has been carefully designed and constructed to meet Passive House Institute US (PHIUS) standards with unique materials and careful attention to details. The wall insulation will exceed California codes with R27 and the ceiling/roof, which is more important for California climate, will far exceed codes at R53. The wall and roof sections are shown in the adjacent details. By paying attention to methods and achieving low ACH (Air Changes per Hour), the envelope does let in uncontrolled unconditioned air or lose its conditioned air through gaps in the building.
The ADU has a sealed and insulated crawl space so that all mechanicals can be run in the crawlspace for ease of modularity and repair/maintenance. The roof system is fully sealed with no attic, this eliminates the air sealing issues with attics. Without a vented attic, the ADU also avoids the main cause of destruction from fire … sparks entering attic vents. Along the same lines, with metal roofing and a combination of metal and stucco siding, the ADU is resilient to fire disasters.
Engineering
Emphasis is on conservation through controls/monitoring and efficient fixtures, appliances, and systems. We also make use of renewable sources of energy and water.
Energy Generation and Conservation
In 2021, the U.S. Energy Information Administration reported that the average American home used 10,632 kWh of electricity annually (source: https://www.eia.gov/tools/faqs/faq.php?id=97&t=3), in addition to natural gas which is often used for heating and cooking. Ekotrope software predicts that our all-electric ADU will use an estimated 4,900 kWh of electricity per year, including electric heating. To meet this estimated yearly estimate and be net-zero, our ADU will have a 5.2 kW solar array and 9.6 kWh energy storage system (ESS). The array is large enough to directly run multiple house systems, including the HVAC, and keep the battery charged. The battery will be used primarily to offset load during peak hours and run the house at night, thus making the house resilient to ever-increasing costs of electricity. Any excess power will be used by the main house to further offset the property owner’s energy bills.
HVAC
The first step for energy conservation is passive solar design and taking advantage of the well designed building envelope described above. Our design uses roof overhangs and a shade structure on the south-facing wall of one of the bedrooms. When appropriate, operable windows enable the use of natural cooling that is typically available many days of the year in the southern California climate. The next step is energy efficient systems. Our HVAC system is a highly efficient, variable speed, DC inverter Mitsubishi mini-split. At 1.5 tons, the system is not oversized. Appropriate sizing is accomplished by creating duct runs to each room from a single concealed duct indoor unit in the crawlspace.
Since the structure is small and lightweight, it lacks thermal mass and will therefore be susceptible to short-term temperature swings, making it both uncomfortable and inefficient as the HVAC system cycles rapidly. To improve HVAC efficiency and comfort, thermal mass will be significantly increased with Phase change materials (PCMs) that absorb or release a significant amount of latent heat without experiencing a significant change in temperature
TeamMADE is using a PCM product, the ENGR Blanket donated by Phase Change Solutions (PCS). With a mass of 0.80-1.0 lb/ft2, it is estimated to be 600-750 lbs spread out evenly on a 750 sq.ft. ceiling. With a thickness of 0.5 inches, the blanket can be installed before the drywall application without compromising wall insulation. A passive method with no moving parts means it is low maintenance and can be used for years without failing. PCS data shows that the ENRG Blanket can reduce HVAC costs by 25-35% by reducing HVAC runtime by 15-20%. The blanket has only been implemented in commercial and large buildings so far and the engineers at PCS expect that the results would be similar for an ADU
Figure. Phase Change Solution’s ENRG Blanket (source: https://phasechange.com/wp-content/uploads/2023/03/ENRG-Blanket-Brochure-6.pdf)
Air Quality
Indoor air quality (IAQ) is critical for health and well-being. In a small, tight house with 4 young men, IAQ must be monitored and maintained. Although the southern California climate is very good for natural ventilation at certain times of the day and year, one cannot rely on natural ventilation alone. Poor outdoor air quality from pollution and ever more frequent fires, along with time when outdoor air is too hot or too cold, necessitates mechanical ventilation. To save energy, the mechanical ventilation system must be as efficient as possible. This is achieved by using energy or heat recovery ventilators (ERV/HRV). We have chosen to use three point-of-use ERVs from Panasonic because they ventilate single rooms and can therefore be turned off when no one is in the room. We will use Air Gradient IAQ sensors to determine when and how hard to run the ERVs. The ERVs can also be unbalanced to offset exhaust only fans in the bathroom and over the range. Finally, this decentralized system is also cheaper and requires less ductwork. We will also monitor outdoor air quality and temperature and be able to alert residents when conditions are favorable (or unfavorable) for natural ventilation. Finally, we will install Panasonic WhisperAir Repair units which use nanoe™X charged water molecules to decontaminate air.
Energy Efficient Appliances
TeamMADE sourced efficient appliances that meet the needs of the residents in the ADU. The energy star certified washer and dryer have ”built in intelligence” which allows them to be controlled remotely through an app so the residents can start a load while they are not home when the typical electric demand is low but ample solar energy is available. The refrigerator is also energy star certified and is large enough to accommodate four grown men, eliminating the need for multiple refrigerators which is the case in the main house. The induction cooktop received an ENERGY STAR Emerging Technology award in 2022 for its efficiency. Induction cooktops heat the cookware directly rather than just the surface of the cooktop like traditional electric stoves and resulting in less energy lost.
Efficient Electric Water Heating
TeamMADE is also utilizing a hybrid electric heat pump water heater (HPWH) that is deemed by the manufacturer as the “most efficient water heater available, ” using 75% less energy than other electric water heaters (source: https://www.rheem.com/product/professional-prestige-proterra-hybrid-electric-water-heater-proph65-t2-rh375-so/). The HPWH has multiple operation modes, one of which utilizes the higher temperature in the day to “superheat” the water when the intake air is warmer to reduce energy consumption. This is a form of load shifting and energy storage. Furthermore, a controlled damper allows the rejected cold air to be used to condition the crawl space, effectively cooling the ADU. The water heater also connects to an app that lets you track energy usage, change operating modes, and schedule set points to adjust the temperature of the water based on the resident’s activity
Controls and Monitoring
Team Made is using Universal Systems EISY device which is an advanced home automation and energy management system. This device allows us to connect to all sorts to devices around the house and control them remotely. The EISY system will have data for air quality, water usage, motion sensing, what devices are running and whether the doors and windows are open. We will also import weather data from weather stations to better predict the energy needs of the house.The EISY system will use live data from monitoring devices around the house to create the most efficient settings and schedules for the house.
We will be using motion sensing to detect when there are people in the house and then use the EISY to change the setting around the house in response to it. Furthermore, the outlets will be able to remotely controlled and can be turned on or off based on the monitoring data.
The EISY will give live update through messages and emails to notify the inhabitants of the house of their energy usage. The Universal Devices app will give the inhabitants easy remote access to the devices around the house and they can control many of the settings of the devices through their phone.
Water Generation and Collection
Fixtures and Appliances and Conservation
Our sink faucets for both the kitchen and bathrooms are touchless; the bathroom faucets (the Kohler Willamette) are fully touchless while the kitchen faucet (the Flow motion activated faucet) offers both touchless and manual operation. The faucets have automatic shutoff times of two and three minutes respectively, preventing waste if users accidentally leave the water on. The kitchen faucet also has additional water saving features, including a retractable hose faucet head that automatically shuts off when returned to its holder and a pause button that allows users to temporarily stop the flow of water while the sensor is still engaged. The use of touchless faucets not only saves water, but also prevents the spread of germs by reducing (or entirely eliminating) the amount of contact users must make with the faucet. Our water-using appliance are also the most water efficient we could find. This applies to the dishwasher and the washing machine.
In combination with a low-flow showerhead and a shower time to encourage residents to shorten their showers from an average of 8 minutes to 5 minutes, our shower setup uses significantly less water than a typical shower.
| Average shower | Our shower | |
| Shower head flow (gallons/minute) | 2.1a | 1.25 |
| Shower length (minutes) | 8a | 5 |
| Water wasted waiting 3 minutes for hot water (gallons) | 7.5 | 0 |
| Water use per shower | 23.1 | 6.25 |
(asource:https://www.epa.gov/sites/default/files/2017-02/documents/ws-ourwater-shower-better-learning-resource_0.pdf)
A water flow monitor will be installed on the ADU’s water main and water usage will be monitored in real time. This can be used to detect leaks, but is also intended to encourage water conservation behavior through quantitative and visual means.
Recirculation Pumping
Users typically leave hot water fixtures running until the water is hot, causing more than 5 gallons of water to be wasted for waiting just 3 minutes. This requires purging the cold water and then waiting for convective heat transfer to do its thing and bring hot water pipes up to temperature. Hot water pipes are insulated, but that does not help the initial heating when there is even 1 hour between hot water usage. The longer the distance to the hot water heater the longer it takes and the more water is wasted. The purpose of a hot water recirculation system is to provide instant hot water to fixtures. Having this system becomes especially important when the water heater is far from certain fixtures in the home, such as in the case of our northeast bathroom. The system we have decided on is the ACT D’MAND KONTROLS ACT1 Hot Water Recirculation Pump, which, when activated, circulates water in a loop that goes from the fixture to the hot water heater. Once all the water in the loop is hot, the pump shuts off. This brings hot water to the fixture without wasting a drop of water. Our system is a demand system that only turns on when the system learns that a resident is about to shower. This is in contrast to the less energy-efficient l systems that always maintain a hot water loop throughout the day or at set times during the day. Furthermore, having placed the hot water heater close to most of the water needs, the recirculation system is only necessary for one bathroom.
Water Recycling and Water Harvesting
Greywater recycling from sink, shower, and washer drains is expensive and only effective in highly controlled environments. On the other hand, encouraging residents to use their rain barrel to store the clean water resulting from washing food is free and can meet a high percentage of water needs for an appropriately designed landscape. When it rains, the slope of the butterfly roof allows for water to collect in a central location to then flow into rain barrels. Another way to passively generate water is with atmospheric water generation. Atmospheric water generation is also utilized as a means to collect water to use for landscaping. Atmospheric water generation involves extracting water vapor from the air and condensing it into liquid water. This can be done actively by using electricity to create cold surfaces that “sweat” in ambient air or passively by using naturally occurring temperature differences to encourage the formation of condensation.
Another potential method involves harvesting condensation formed through radiative cooling on our roof. The roof absorbs heat throughout the day, raising its surface temperature. When the ambient air temperature drops at night, the temperature difference between the roof and the surrounding air encourages the formation of dew on its surface. By coating the roof with a mix of hydrophobic and hydrophilic substances, we can force the dew to roll down the roof and into our rainwater storage barrels.The butterfly roof design also allows for rain to flow nicely into a gutter system for easy rainwater collection to use for landscaping.
Innovation
Using FrameCAD for easy to customize/assemble, near-zero waste light-gauge steel framingMeet Passive House Institute US (PHIUS) climate specific standardsFacilitating water harvesting by enabling collection of night time condensation Saving energy with controls and monitoring to reduce unnecessary electricity use and encourage behavior changeIncreasing Phase Change MaterialContinuous indoor and outdoor air quality monitoringStoring hot water by running heat pump hot water heater longer during more efficient daytime hours AND using the rejected cold air for cooling