How to Achieve Energy Efficiency Through Designs in Buildings (Part I)

Zona Li
Zona Li
Aug 27, 2017 · 3 min read

According to the Annual Energy Outlook 2017 published by EIA, in 2016 U.S. homes used about 1.4 TWh of electricity, which accounted for 36.6% of total electricity end use in the U.S.[1] Among the 1.4 TWh electricity used, heating (space heating and water heating) and cooling constitutes 34% of the total consumption, the rest of the electricity is used (listed at a decreasing electric energy consumption order) for others[2], lighting, refrigeration, television, dryers, furnace fans and boiler circulation pumps, computers, cooking, dishwasher, freezer, and clothes washers. We can infer from those numbers that a decrease in residential energy consumption will have a huge impact on the overall energy usage and greenhouse gas emissions. Therefore, it is worth for us to explore different ways of designing our homes in order to make it more energy efficient. In this article series, I will look into the design criteria for energy-efficient buildings including the structure, building materials, orientation, and appliances and electronics we use inside of the building.

It is more cost effective to include sustainable strategies into the design phase of the building and build accordingly than to retrofit an already existed building. The user of the building will start saving energy from day one, and the initial investment cost for a “greener” building will be paid off in the lifetime of the building. Throughout the lifecycle of the building, there will be fewer carbon emissions compared to that of a conventional building, therefore society as a whole will also benefit. The average age of a typical residential building in the U.S. is 32 years and most well-designed houses are able to operate in its optimal condition for decades. It is surely worthwhile and economically desirable to design for long lasting and highly efficient houses. A good design has been shown to possess huge potential for reducing the space heating and cooling energy consumption. In Canada, the residential sector uses around 17% of the total national end-use energy. Because of the cold climate, 63% of this energy used is for space heating[3]. However, using a BIPV/T system with a ventilated concrete slab, a prefabricated house built in Canada in 2007 called Éco Terra can achieve nearly net-zero energy consumption. The house is tightly insulated, the size, orientation, optical and thermal properties of its windows are designed to maximize passive solar gains during winter, the roof with the building-integrated photovoltaic/thermal (BIPV/T) system will generate solar electricity and heating for the house. One problem facing the BIPV roof is overheating, which would reduce the efficiency of the electricity generation. This is mitigated by combining solar PV with solar thermal: the heat absorbed by the solar PV cells is collected through a ventilated air gap underneath the roof, which can be used for heating up the space or heating up water through a heat pump. The entire system is highly cost-effective[4]. Éco Terra’s annual heating energy consumption is 1600 kWh, about 5% of Canada’s average annual heating energy consumption.

Source: Annual Energy Outlook 2017
Éco Terra
Source: Modeling, design and thermal performance of a BIPV/T system thermally coupled with a ventilated concrete slab in a low energy solar house: Part 1, BIPV/T system and house energy concept.

It is fairly obvious that houses with an eco-design will save a considerable amount of energy over the years. Transitioning to zero net energy buildings in both residential and commercial sector is a crucial step towards reducing the world’s energy consumption. In the following articles, I will look into the ways or requirements for building a high-energy performance building and assess the potential energy saving each method could achieve.

[1] https://www.statista.com/statistics/201794/us-electricity-consumption-since-1975/ & https://www.eia.gov/totalenergy/data/annual/showtext.php?t=ptb0809

[2] Small electric devices, heating elements, exterior lights, outdoor grills, pool and spa heaters, backup electricity generators, and motors

[3] http://www.nrcan.gc.ca/energy/products/categories/water-heaters/13735

[4] Photovoltaic cogeneration in the built environment by M.D. Bazilian, F. Leenders, B.G.C. Van der Ree, D. Prasad (2001)

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Zona Li

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Zona Li

The less things you identify yourself with, the less foolish you become.

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