It doesn’t matter where in the world you live, the time has come to realize the importance of building homes that use zero energy. You don’t even have to believe in catastrophic global warming to realize the financial, comfort, and environmental benefits of net-zero homes.
But first, you need to have an understanding of net-zero and zero-carbon buildings and their implications for us all, as well as the elements and features that need to be incorporated into a net-zero home.
Net-Zero Homes and Energy Efficiency
You could say that a net-zero or zero-energy home represents the best in energy efficiency. Essentially, the energy they consume each year is equivalent to the renewable energy they produce, resulting in a carbon-free environment with a net-zero bill. Additionally, zero-energy homes are sustainable, healthy, very comfortable, and, believe it or not, affordable. Often they are smaller in size which adds to affordability.
As the picture above illustrates, a net-zero home will be energy-efficient from top to bottom. It will have:
- Insulation in the roof and walls that helps to create a thermal envelope that will keep the building airtight. Good insulation will reduce heating needs as well as cooling demands.
- Good ventilation and air filtration that maintains air quality for those living in the house.
- High-performance windows that filter light and minimize penetration of solar heat. Windows must also seal against drafts, adding to the performance of the thermal envelope. Windows should also be designed for cross-ventilation in summer to make use of natural ventilation and reduce the cooling load.
- High-performance doors that also help to reduce heat loss.
- A heat pump and/or solar photovoltaic (PV) panels for water and space heating. Heat pumps also offer an energy-efficient alternative option to air conditioners and furnaces and can reduce electricity used for heating by as much as 50%. A heat pump water heater provides very efficient electric water heating.
- Low-flow water fixtures in bathrooms, kitchens, and laundries. These operate with high-pressure, producing a consistently strong flow of water that reduces water flow by more than 30% ultimately using less water and reducing the use of hot water specifically.
- Energy-efficient lighting that uses about 75% less energy than old-fashioned incandescent lighting. The key is to use light-emitting diode (LED) or compact fluorescent lamp (or light) CFL light bulbs.
- Energy-efficient appliances, including induction stovetops, that use renewable sources of energy and are designed to function with minimum energy.
- Excellent energy management that optimizes energy use throughout the house.
While net-zero homes are generally new buildings, some upgrades can be done to make older homes more energy efficient, particularly by:
- Improving wall framing if the house is timber frame
- Adding insulation
- Installing solar PV energy systems
In the U.S. and some other parts of the world, it is possible to get energy-efficient mortgages and even loans to cover upgrades to make your home net-zero or at very least more energy efficient.
In terms of cost, a specialist (MEP) engineering firm in Chicago, New York, or whichever city you live in or near to will be able to advise.
Different countries, and even different states and areas within countries are moving at a very varied rate towards the World Green Building Council’s goal to have all new buildings net-zero carbon by 2030 and all buildings by 2050. Some will make it, clearly, others won’t. Similarly, some want to and others don’t seem to care.
In the U.S. for instance, California initially took the lead in terms of net-zero buildings although Massachusetts was recently ranked the most energy-efficient state in the U.S. by advocacy group the American Council for an Energy Efficient Economy (ACEEE). According to their 2018 State Energy Efficiency Scorecard, Massachusetts scored 44/50 while California sored 43.5. At the other end of the scale, Wyoming had an abysmal score of only 4.5/50.
On the other side of the world, the UAE has pledged to be a global leader in sustainability, aiming for new “nearly zero energy buildings” by the end of next year (2020). This means that all new buildings, including homes, will have low energy consumption and they will use renewable energy for most needs. It is also part of a plan to develop a low energy, low carbon economy that will set an example for all the other countries in the Middle East region.
Having said that it doesn’t matter where in the world you live when it comes to net zero, climatic, economic, and other differences do impact on viability. Even traditional design practices and building methods in some regions have a significant influence. For instance, in the Middle East and North Africa (MENA) region as a whole, energy prices and the costs of trying to implement energy efficiency measures are very real factors.
Researcher Moncef Krarti did a relatively recent study that evaluated net-zero energy residential buildings in the MENA region focusing specifically on the cost-effectiveness of designing residential buildings that would minimize lifecycle energy costs. He concluded that it was vital to reduce energy subsidies in the MENA region, and ultimately eliminate them.
The ACEEE suggests other strategies including more stringent building energy codes and an improvement in code compliance in some states, and to find innovative financing mechanisms to lower up-front costs in others.
While the challenges and success rates vary, it is generally agreed that net-zero homes cost about 10% more to build than those that don’t comply with energy-efficiency requirements.
But with an acknowledgment that buildings are responsible for a very big percentage of the total energy used (40% in the U.S.), it is a fact that zero-energy homes are one of the cornerstones of a globally reduced carbon future that isn’t going to rely on harmful fossil fuels.
Certainly, net-zero is the way to go.