ZERO ENERGY BUILDINGS

TRANSFORMING CONSTRUCTION IN FAVOR OF THE ENVIRONMENT

Written by: Ing. Raul Mora Alvarado

We can say that a zero energy building is a building with a high level of energy efficiency where the little amount of energy required must come from renewable energy sources, so that its energy balance is zero or almost zero.

 

The advantages of these buildings in the fight against climate change and energy dependence on fossil fuels have convinced the governments of many countries to invest in their development, although the high construction price and the low development of these technologies slow down due to the moment its generalization. 

These buildings are connected to the local power distribution network to receive power when renewable energy production is insufficient to meet required demand and to return power to the local power grid when power production exceeds required demand.

Achieving zero energy is an ambitious goal that is increasingly achievable and of great importance worldwide, both government institutions and the private sector are moving towards the implementation of Zero Energy Buildings. A Zero Energy Building produces enough renewable energy to meet its own annual energy consumption, reducing the use of non-renewable energy. 
 
Some long-term advantages of moving towards Zero Energy Buildings are: lower environmental impact, lower maintenance and operation costs, fewer impacts due to power failures or natural disasters, and improved energy security.
 
There are some advanced energy design guidelines for Zero Energy Building construction, created through industry partnerships with ASHRAE and other market leaders. Reducing building energy consumption in the renovation or construction of new buildings can be achieved through several means, including integrated design, modernization of energy efficiencies, reduction of connected loads, and programs for energy conservation.

On the one hand, active systems to achieve electricity and air conditioning based on renewable energies offer several possibilities, such as solar panels, wind turbines, biofuels, biomass or hydrogen-based fuel cells. For example, a building that only incorporates photovoltaic solar panels can achieve a reduction of its energy needs between 15% and 30%.

On the other hand, passive techniques, such as thermal insulation or the use of solar or even metabolic heat, generated by its occupants, can reduce the energy consumption for air conditioning the building by between 70% and 90% unnecessarily of electricity generation systems.
 
In short, a Zero Energy Building incorporates a series of technologies in favor of the environment that to achieve its objectives can make a combination of passive energy efficiency systems and active electricity generation systems through renewable sources to obtain a more favorable result.
 

Therefore, before starting a construction, the designers of these ecological buildings use sophisticated 3D simulation computer tools to incorporate, in the best possible way, aspects such as the location and its orientation, the local climate, the materials used, the thermal insulation , lighting, or the efficiency of electrical and air conditioning elements. In these types of buildings, environmental consultants or bioclimatic experts are an important part of the architectural project.

The UK has taken the implementation of this type of green housing very seriously. In December 2006, the government announced that by 2016 all newly built houses must be zero energy. In that sense, the British standards that currently regulate this sector do not require building following these principles, but they will be increasingly strict in the next nine years, in line with the Code for Sustainable Houses, so that it can be achieve the stated objective.

Germany is one of the country’s most aware of the sustainability of housing. The standards of the German “Passivhaus” have been a world reference for years, elaborated with modern technologies of passive energy efficient systems. Also, some of its designers show that they are at the forefront of these technologies. In the international “Solar Decathlon” competition, promoted by the US Department of Energy, a Green House design from Darmstadt University of Technology won first prize.

Outside the European Union, the United States is another of the international benchmarks in this type of sustainable construction. In 1999, the Florida Solar Energy Research Center laid the foundations for programs such as “Zero Energy Home” or the “Building America” of the US Department of Energy (DEO). Likewise, the various research laboratories throughout the country work on sustainable building research programs. In this sense, the DEO has announced various plans with large sums of money to invest in this type of project.
 
For zero energy buildings in the United States, several examples can be cited. One of the first zero carbon commercial buildings in this country opened in October 2007. Located in San Jose, California, it was the building of the sustainable design company Integrated Design Associates (IdeAs). For its part, Google has just finished a solar electricity system for its Silicon Valley headquarters, capable of generating 1.6 MW (enough to power a thousand houses) and covering a third of its facilities.
 
In addition to the United States, other countries are also developing various zero-carbon building initiatives. In Canada, the R-2000 standard has also been a world benchmark in low-energy home construction. In addition, the “Net-Zero Energy Home” is a Canadian industry association that promotes the construction of zero energy homes. For its part, the Canada Mortgage and Housing Corporation sponsors the Equilibrium Housing competition, which will allow the construction of twelve projects of this type of housing throughout the country.
 
For its part, the Asian continent also provides spectacular examples. In the city of Guangzhou, south China, Skidmore Owings & Merrill Company plans to complete a 69-storey office skyscraper based on the principles of zero energy by 2009. And in Malaysia, Ruslan Khalid Associates inaugurated in October 2007 the “Zero Energy Office” (ZEO), an office building for Pusat Tenaga Malaysia (PTM), a non-profit company promoted by the Minister of Energy of this country.

However, the construction of Zero Energy Buildings also poses a series of disadvantages that must be taken into account. One of its main disadvantages is that the use of these technologies, especially the installation of renewable energy sources, usually implies higher initial construction costs compared to conventional buildings. The medium-term prospects is for this type of technology to become widespread and improve, reducing its costs, something that may be an advantage for this type of housing in the future.
 
The ideal of these buildings is that they can be self-sufficient, without the need to be connected to the electrical network. However, to achieve this, large initial investments are required, which currently need to be subsidized in order to carry them out. For this reason, their designers usually connect them to the electrical network to be able to respond to fluctuations in the demand for heat or electrical energy.

Bibliographical sources
1.- National Renewable Energy Laboratory _ Accelerating to Zero Energy District
2.- Eco Inteligencia _ ¿Que es un Edificio de Energía Zero?
3.- US Department of Energy _ A Common Definition for Zero Energy Building
4.- ASHRAE _ Achieving Zero Energy