Building Science is continually evolving and getting more efficient so how to get to netzero is subject to change but here is our best for now 🙂 Check out the end of the post for how to renovate your home in stages to NetZero, everyone can have this!
What is NetZero? Why does it make sense?
- A NetZero home is one that produces as much energy as it uses each year so it no longer contributes to global warming.
- Buildings are 45 percent of the global carbon emissions problem so homeowners, architects and building designers have a lot of power to change sea level rise and the other major concerns we are encountering worldwide.
We need to create a building that uses less energy than before because it is better built and has the ability to generate its own energy.
Let’s look at how to design a house in preparation for NetZero use:
Passive Solar Design: What is this?
It is usually not possible to get this exact, as sites differ, but the intent is below.
- In passive solar building design, windows, walls, and floors are made to collect, store, reflect, and distribute solar energy in the form of heat in the winter and reject solar heat in the summer
- Design the house to use the sun, breezes to heat and cool.
- East West Orientation in the northern hemisphere: (Orientation is different in southern hemisphere)
- Design the building long in the east west face, maximizing the south face. The north face has very little windows and more thermal mass.
- South facing sun: in the summer when it is too hot, the angle of the sun is very high so an overhang can keep your house cool
- In the winter, the south facing sun is low in the sky and can bring in the sunlight to the interior to warm the home.
- We can create models on our computers to show where the sun will travel around your home.
Thermal mass: what is this?
- Thermal mass captures the sun’s energy
- In the daytime, the sun comes in and heats up the thermal mass, it soaks the heat up
- In the evening the concrete, stone or other thermal mass material radiates off the heat slowly, heating the home.
Air movement to passively cool:
- Air movement is not always used for NetZero as a really tight and efficient envelope is more energy saving but it depends on individual house design
- we can modify other elements to use passive cooling.
Energy efficient building envelope:
To get to netzero it helps to have a really energy efficient building envelope, basically a blanket over and around your structure to keep heat in when its cold outside and keep cool air inside when it heats up. Insulation can provide half of the heat needed to heat your home.
Does that mean the air is stuffy inside?
- there is a system which will bring in fresh air from the outside
- the air goes through a unit that captures the heat content of the air to make it similar to what is inside the house and releases it into the home
- It also removes air continuously from the house so you get a very fresh house
- This system has filters so it actually can be really helpful if you have someone prone to asthma or allergies in your family
How do you get an energy efficient envelope?
- Insulation is cheap and you will lose less energy heating and cooling so you insulate all the building envelope, windows and doors, below slab, walls above grade, walls below grade and roof
- Closed cell insulation has become more and more energy efficient but is higher cost
- We will cover options to super insulate your home in another Orla Studios Guide.
- The diagram below is just one option using regular insulation and double wall construction from fine home building magazine but there are lots of less labor intensive options!
- For windows and doors, manufacturers are bringing out more efficient models every year so you do not necessarily need to use triple glazing anymore to get to netzero.
How do you test for a no leak tight exterior envelope:
- Sealing up the house perimeter is important so there are no air leaks.
- There is a test your contractor can do call a blower test to see how airtight the envelope is.
- There are a number of new products on the market to help seal the natural openings created during construction that we will cover in another Orla Studios Guide.
So how do you make your house use as little energy as possible:
Let’s look at the typical energy users in your house:
Heating and cooling:
- HVAC equipment designers work with the most efficient compressors, fans, and pumps, coupled with advanced controls, to meet the net-zero energy goal. The result is a more efficient system that uses less energy and saves operational costs.
- Smarter controls and the Internet of Things (IoT) are playing a large part in ensuring a building is operating as efficiently as possible.
Here are some of the most efficient and green options for heating and cooling your home:
Geothermal energy is thermal energy generated and stored in the Earth.
If the ground temperature is warmer than the ambient air temperature, the heat pump can move heat from the ground to the building. The heat pump can also operate in reverse, moving heat from the ambient air in a building into the ground, in effect cooling the building. Ground source heat pumps require a small amount of electricity to drive the heating/cooling process.
Ductless Heat Pumps
Air-source ductless heat pumps (DHPs) require no ducts or water pipes and are sometimes referred to as mini-splits. In addition to saving energy, they cost less to install and create only two penetrations in the building shell. DHPs can be sized accurately to meet the needs of small, efficient homes, which makes them a good match for many zero energy homes.
Hydronic radiant heating and cooling is used in 50% of net-zero energy buildings. It’s a cost-effective way to downsize forced-air HVAC systems, cutting energy use yet enhancing comfort.
Use Heat pump water heaters:
Takes heat out of the air and uses it to start to heat the water so you use less energy to get hot water.
Some models have both input and output ducts so you can have a water heater that blows cold air.
Huge energy savings. Standard electric water heaters uses $500 per year for family for four, heat pump is $208 per year.
Induction cooktops are instant on, instant off and all electric so you can use your solar panels to operate them. They use magnets and are really efficient using special pans, see egg below, the cooktop stays cool always so it is safer for your family.
There are heat pump dryers that are terrific. Diagram below of how it can help
There are many wonderful LED lighting options now to light your home using very little electricity.
How does your home generate its own energy?
This is where you generate power and we can do calculations to figure out how many panels you need to get to NetZero. It depends on the local utility how they value the energy you provide and how much you can save.
More and more affordable options are being developed every day. Wind power has about a quarter of the carbon footprint of solar panels which means the manufacturing process contributes less to global warming.
- An advantage of the microturbines required for home use is that they need less wind to begin turning than their commercial cousins.
- Being smaller they generate less power
- Small wind turbines are defined as producing less that 100 kilowatts per hour, usually less than ten, with quite a number generating more like 1.5kW/hr.
- The higher above the roof the turbine can be positioned the stronger the breeze will be. Wind speed increases at the seventh power above effective ground level.
Electric car: Not really part of the netzero equation but will save you money if you build a netzero house
Netzero will be a requirement in California for new houses starting 2020.
Tumble Creek Cabin #coate
How the home above got to Netzero:
- High-performance rain screen building envelope with continuous exterior insulation
- Over insulated roof beyond required Washington State Energy code minimums
- Radiant floor heating and Energy Recovery Ventilation System
- 10 kWh PV Solar Panel array, engineered for Tesla Powerwall battery backup system
- Use of rustic materials, including stone, Cor-ten steel, and reclaimed barn wood with modern detailing
- Exposed steel and wood structure throughout the main spaces
- Radiant Heat
- Heating and ventilation system can be monitored and adjusted remotely
- Massive board-formed concrete fireplace
- LED lighting
- Energy efficient aluminum-clad wood windows and doors
- Electric car charging station
You can also renovate your home to NetZero in steps: check out one of our favorite Canadians who does just that:
#renovate #netzero #globalwarming #stopglobalwarming #cop24 #cop25 #solar