Solar Secrets to Energy Savings

An image of a newly built home, complete with solar panels on its roof.
Energy Efficiency
Solar designed homes come with a variety of benefits and can be paired with the latest in home comfort technology for the ultimate in efficient comfort.

Homes can be kept cool on hot days, heated in winter and lit during the day by designing them in a way that takes advantage of the sun’s path over the seasons.

This is called passive solar design.

Ancient Civilizations

The solar design idea is not new. It was used by ancient civilizations to escape extreme heat. Today’s designers update the technology with modern materials, methods, and software.

Solar designed homes can be costlier to build than conventional structures but are often less expensive over time. They use less energy and are easier to maintain. They maximize comfort by using natural light, ventilation and the sun.

A ductless-split system can further increase the comfort level of the home while keeping efficiency to a maximum.

Understanding Solar Geometry

Solar design need not be complex, but builders must understand solar geometry, window technology, thermal principles and the local climate.

First, make sure the home is well sealed and insulated so it retains the maximum heat in winter and coolness in summer.

Windows South

To help heat the house in winter, designers should make sure it has an unobstructed view to the south.

Windows or other devices that collect solar energy should be large and face within 30 degrees of true south. During the heating season, windows should not receive much shade between 9 a.m. and 3 p.m. Glass naturally lets in sunlight and traps heat radiation. This is known as the greenhouse effect.

Unobstructed Rays

In urban areas, solar designers should take into account the possibility of future neighboring developments shading the property. They should build houses at the north end of a south-facing property to ensure unobstructed access to the sun even if neighbors build nearby.

Only a few windows should face north. Designers should place some windows on the east and west sides of the house for daylighting and cross-ventilation.

They should install high-quality windows that are tightly constructed and have at least double-insulated glass. 

Window Shading

During hot months, property owners can shade windows so they don’t overheat, for instance by using trees and roof overhangs.

On cool nights, they can reduce heat loss by hanging insulating window blinds or drapes.

Solar energy moves into the house by three methods: direct gain, indirect gain and isolated gain.

Direct Gain

In direct gain, sunlight enters through windows and hits masonry floors and walls, which act as a thermal mass, absorbing and storing solar heat. At night, when temperatures drop, the floors and walls release heat into the home and warm the air.

Indirect Gain

In indirect gain, a storage mass such as masonry or water collects and stores heat directly from the sun and then transfers it to the interior space. Builders can choose from several indirect gain passive systems, including roof ponds, water walls or Trombe walls, which are masonry or concrete walls covered externally with a glass skin.

Isolated Gain

In isolated gain, a separate room enclosed by large windows absorbs the sun’s rays. This is typically seen in sunrooms, solariums or solar rooms. 

Passive solar home design can lighten the heating and cooling load. The remaining load can be met by an efficient cooling and heating system, such as a ductless mini-split heat pump.

Solar designed homes come with a variety of benefits and can be paired with the latest in home comfort technology for the ultimate in efficient comfort.


Sources:

U.S. Department of Energy: Passive Solar Home Design

Passive Solar Design Technology Fact Sheet (Direct Download, PDF)

Mother Earth News – Passive Home Design Basics

University of Southern California


This article and its content are sponsored by Mitsubishi Electric US Inc., Cooling & Heating Division. 

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