Difference between revisions of "Heating and cooling system"

Revision as of 14:39, 27 August 2012

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Introduction

We have designed a system that integrates passive and highly efficient active systems to create an ultra-efficient and healthy HVAC system for a building. The rationale for a hybrid type system is to allow the earth's natural systems (e.g. the sun and earth) to do as much of the heating and cooling work as possible, and only when they cannot meet the required heating and cooling levels are high-efficiency mechanical systems required to complete the job.

Strategy for our hybrid heating and cooling system

• Reduce the demand for heating and cooling by utilizing passive design ideas.
• Use solar thermal panels to heat water that is stored in 2 stainless-steel insulated tanks (totaling 5,000 gallons). That water will be pumped to manifolds under our floors, which will send the water out in pex tubing (also under the floors) to provide a radiant heating system.
• Use an Altherma Heat Pump as a back-up system when there is not enough sun.
• For cooling, we are blowing a fan over a dehumidification coil.

Why is it important?

This hybrid system is important to a building's sustainability because it:

• Directly connects the building and its occupants to the earth's natural systems (e.g. sun panels and earth loops)
• Demonstrates an "appropriate" use of technology (only after the natural systems are unable to meet the needs).
• Includes renewable, high-efficiency, low-carbon components (e.g. solar panels, earth loops).
• Reduces energy operating costs because of ultra low energy usage.

Overall Conceptual Design

Geo-Solar Hybrid Heating and Cooling - Shown in Heating Mode (01/22/10)

More detail

Solar thermal panels

The solar thermal panels component captures the energy from the sun and uses it to heat water running through the panels. The panels are connected directly to thermal storage tanks, so the sun's energy is stored in the water in the tanks and drawn on by the radiant floor system when needed.

Mass thermal storage

We have 2 thermal storage tanks, one approximately 3,500 gallons, and one approximately 1,500 gallons, in the annex. They are connected to the solar thermal panels through the roof, and connect to pex tubing that carries the water from the tanks to manifolds located throughout our floors. The manifolds disperse the water under our floors to heat the building in a radiant-heating style.

Radiant floors

A radiant floor system is used to heat the Green Garage building. The system is integrated into the floor system in zones sized to meet the heating and cooling demands of the particular zone.

Integration and Controls Design

Integrating all the components of the hybrid heating and cooling system did require significant design effort. Some of the controls are manual and some are automated. The key integration areas are:

• The integration of the heat pump with the mass storage system. This would be temperature controlled with the heat pump coming on only when needed.
• The drainback system of the solar panel system is temperature controlled.
• The changing of the thermal storage from winter heat mode to summer cooling mode is done manually.
• The supply-demand mixing valve for the radiant floors controls the temperature of the fluid in the radiant floor tubing (pex).
• Integration the air distribution system to accommodate air from any source.
• Automation the moisture control with all other components.

See Also

• Geo-Solar Hybrid Heating and Cooling Design page for heating and cooling
• Super Insulated Building Envelope
• Hybrid Ventilation System
• Solar thermal panels
• Mass Thermal Storage
• Radiant Floor Heating and Cooling