Heliocentric in Salt Lake City, UT is an energy and environmental engineering firm that provides technical assistance, consulting services, and systems solutions to owners, architects, builders and engineers. They specialize in the engineering and design of high performance buildings and communities, passive buildings, net-zero homes, and sustainable whole-building energy solutions. Recently they installed an eSense CO2 monitor to work with one of their installations.
The SenseAir eSense CO2 transmitter monitors CO2 levels throughout the day. This gives a sense of occupancy levels and allows the system to turn on and off the fresh air ventilation as needed. This way they can supply the necessary fresh air without over ventilating. In addition, they use a heat recovery ventilator (HRV) to supply fresh air without losing conditioned air.
Data from the meter is fed into a smart controller and gives the homeowners a readout of the CO2 levels in their home in their HVAC control software. Additionally, it activates the home's outdoor air ventilation system when CO2 levels get too high.
For heating and cooling, they used a geothermal water-to-water ground source heat pump to supply heated and chilled water to the radiant floors throughout the house. The heat pump also supplies the majority of the domestic hot water.
For insulation, they worked with the architect to create a high-efficiency thermal envelope for the home. The walls have 4" of EPS foam in addition to the standard 5.5" of blown in insulation. The roof is constructed similarly with blown in insulation between the joists and EPS foam sheathing on the outside. There is 4" of foam under the slab and on the subgrade walls. Windows are triple pane. The house is also extremely well sealed. Before insulation was blown in and used a blower door to find all of the smallest cracks, gaps and holes. As a result, they achieved an AC50 of about 1.6.
While this type of energy-efficient home might be considered custom today, in the future many of these technologies will be standard on all modern homes.