Founder | BPI® Energy Auditor Certified Professional
Why is everyone so excited about net-zero construction?
When you go into a house built using net-zero construction components and techniques, you won’t notice anything obviously different. But a net-zero energy home will feel different.
There won’t be any sci-fi movie doors that slide open as you approach and close again after you walk through. But you’ll have a computer program working silently in the background to monitor and control your energy use so you don’t waste any energy.
In this article, we cover some of the main differences that you’ll find when using net zero construction versus traditional building with none of these optimizations in mind.
So How is Net-Zero Construction Different From Regular Construction?
As opposed to regular or traditional homebuilding, the main objective of net-zero construction is energy efficiency, and other benefits flow from that. You get a house that is comfortable in ways you may not expect. Temperatures are even throughout, with no drafts. It’s quiet. The air is fresh and clean, along with saving on the utility bills for the life of the home.
Net-Zero Construction is based on building science, which has revolutionized home building. It combines thoughtful designs with careful construction practices and computer controls. In this framework, novel energy-efficient building components and equipment work together to minimize energy use. On-site generating equipment offsets out the energy consumption.
Elements of Net-Zero Construction
If you’d like to learn more about the specifics of what makes net-zero homes different, read on! You’ll find quite a few differences between net zero construction and older construction methods.
Site Factors
The house is oriented to take advantage of the sun and natural shade (if any). You want to make the most of the sun for heating and take advantage of any natural shade to minimize the need for cooling. Traditional construction looks toward the aesthetics of the site placement.
There may be trade-offs here depending on your environment; these are design issues before the first nail is driven. Hot climates and cold climates have different concerns that can determine the best location of rooms and windows.
Air Sealing
Sealing all the gaps between building components keeps the air inside your net-zero energy home once it’s been heated or cooled. The joints where walls meet each other at corners, where walls meet floors and ceilings, all around the roof, around windows and doors—all these joints are carefully sealed.
There are many other places where openings in the building structure could allow air to leak out. You have to make sure that you seal all the holes where pipes and electrical wiring penetrate walls or other structural elements.
None of this was done in older construction. If you measure all the gaps and holes in a typical older house of moderate size, they add up to a single hole about three feet in diameter. That’s a lot of leakage!
Attics are a particular area of attention in net-zero energy homes, as houses can have quite a bit of energy loss through their attics. You’ll often have an attic that is part of the house, heated and cooled like everywhere else.
Windows and Doors
Windows and doors in older construction leak energy, but in net-zero construction, we use double or triple glazed windows that are much more energy-efficient. You can specify their glass for different locations in the house, depending on, for instance, whether you want to let the heat of the sun come in or not.
These new windows and doors are well-sealed around their moving parts, and their installation is different. As a result, they do not allow the heated or cooled air to leak out, like older windows and doors.
Insulation
Walls, ceilings, and floors are well-insulated to keep the inside temperature inside and the outside temperature outside. Insulation is carefully installed, unlike in most regular construction. Even minor irregularities in the insulation can disproportionately reduce its effectiveness.
The walls may be thicker to allow room for more insulation. The underside of the roof may be insulated so that your attic is part of the house, or else the topmost ceiling is especially well-insulated.
Heating and Air Conditioning Equipment
The heating/air conditioning system itself gets special attention in a net-zero energy home. Older homes typically waste one-third or more of the heating or cooling energy. The systems were not carefully designed or installed; sometimes, the contractor will use whatever parts are available if the specified ones aren’t in stock,
A model uses complex calculations to create a design that minimizes energy use. The design specifies the ducts’ size, length, and insulation to provide the precise amount of heating and cooling needed in each room. It also gives the optimum size and capacity of the equipment.
You’ll have diffusers that spread the air evenly in each room; there are literally thousands of models for every different situation. Most heating/air conditioning contractors choose from only a handful, so they don’t get good results.
In most net-zero homes, you’ll have a heat pump instead of a gas-burning furnace. Heat pumps can run in reverse to either heat or cool. The most efficient systems are ductless: individual blowers are installed in each room, so rooms are heated or cooled independently.
Advanced technologies are available to provide highly energy-efficient operations.
Ducting Systems
Many heat pump systems and all gas-burning furnaces use ducts to distribute air from where it is heated or cooled to each room. In older construction, carelessly installed ducts typically result in the loss of 20%-30% of your energy. You could lose as much as 70% of your cooling dollar in some cases.
In net-zero construction, ducts are no longer than necessary. Installers are careful to seal all the joints very well so they don’t leak. The ducts are insulated, in some cases heavily insulated, to reduce energy loss.
Water Use Efficiency
You’ll have low-flow fixtures for water use efficiency. Your showerheads and sink faucets will all be reduced flow. Toilets will be 1.2 gpf. Older fixtures were water-wasters.
You may even have a system where you turn on the hot water, and while you are waiting for it to get hot, it flows back to the water heater instead of going down the drain. When the hot water reaches the sink or shower, water comes out—not before. A lot of water was wasted waiting for it to get hot in older plumbing systems.
Efficient Water Heating
Net-zero construction uses energy-efficient water heating equipment. It might be tankless; it might heat with electricity or gas. You can now get a heat pump-based water heater for the ultimate in water heating energy conservation.
Your hot water pipes are insulated along their entire length to minimize heat loss.
Traditional construction used tanks heated with gas; the tanks and the uninsulated piping wasted a lot of energy.
Ventilation
Ventilation is essential for creating a healthy environment. In regular construction, you got your ventilation from a leaky structure, which barely restricted air exchange between inside and outdoors. Since net zero houses don’t leak at all, a new system was required.
Your net zero ventilation system recovers energy from the air it exhausts and puts it into the fresh air intake. This helps minimize your energy loss while giving you fresh air and expelling pollutants.
Your ventilation system also regulates the humidity in your home, keeping it around 50%. Molds thrive at high humidity, and bacteria thrive at low humidity—in the middle is the best level for you.
Efficient Lighting
You’ll have efficient lighting using LEDs. LED lighting uses much less electricity than other kinds.
And it has improved to the point where it is better than the older types of lighting in many ways. The lights last much longer, and you rarely have to replace them.
Energy-Efficient Appliances
You’ll have Energy Star appliances, developed and certified to be the most efficient ones available: refrigerators, washers and dryers, microwaves, cooktops and stoves, ovens, exhaust fans, etc. These were developed to replace older models that didn’t care how much energy they used.
Energy Management System
A basic energy management system gets to know your daily patterns, or you can program it. The system regulates heating and air conditioning to your schedule, turning it on before you get home and before you wake up, turning it off when you go to sleep or leave for work.
An advanced system will even track your movements through the house to turn lights and heating/air conditioning on and off.
All you had in older homes was a manually operated thermostat.
Solar Cells or Other Generating Equipment
In most cases, you’ll choose solar cells for generating the electricity to offset the house’s power use. They are relatively inexpensive, and specialists know how to install them properly.
Less-common ways are starting to appear in net-zero energy homes, although they tend to be more expensive. Huge windmills have gained widespread use to generate lots of electricity; now smaller ones are available to serve a house. Geothermal power generation may be an option for certain areas.
Conclusion
So, you can see that the components used in net-zero construction are different and they are installed differently; they are quite energy-efficient. The workmen are much more careful so that nothing leaks. The systems that support the house are different; computer controls minimize energy usage.
All this adds up to a house that is very different from typical older ones, but is packed with so many benefits that it just makes sense.