A ‘passive house’ is an energy-efficient home built to the highest standards of energy efficiency. It is a modern alternative to older energy-inefficient homes.
Passive houses are designed with very high levels of energy efficiency. A passive house is well below 0.5 energy factors, while a typical new home is around 2-10 energy factors and an efficient office building may be around 30 energy factor.
In this article, we will discuss the basics of passive house design, the different levels of passive house design, the types of passive houses, and the advantages of building a passive house.
You have to keep in mind that it is still quite challenging to build a house that is completely passive in some locations that don’t receive a lot of (sun)light. In other locations, it is easier to do this. Engineers are developing new materials to make it easier to build this type of house. We can expect big advances in the coming years as new technologies come to the market.
Types of passive house
There are many different types of passive houses, but they all have one thing in common: they are all designed to very high levels of energy efficiency.
Some of the more common types of passive houses are:
- Zero energy: using the most energy-efficient technologies available, consuming as little energy as possible while still providing all basic domestic needs
- Energy Positive: using solar power, T&D losses are minimized, overhead is nil
- Net Zero energy: energy is completely offset by renewable energy or energy-efficient technologies or both. A net-zero energy passive house is designed to consume as little energy as possible while providing all basic domestic needs. These needs include: hot water, water for hygiene and appliances, and electricity for lights, appliances, and essential services.
- The main differences between a net-zero energy passive house and a typical suburban home are the solar panels, energy-efficient appliances, efficient lighting, and a high level of insulation.
To achieve this advanced software is used to make sure that everything runs smoothly. Solar panels, specific materials, and ventilation are installed to make sure that the home can produce its own energy as much as possible and doesn’t have to use a lot of external energy. Most homes need more energy during the winter to heat it and during summer to cool it down. Passive houses try to avoid this peak in demand by adding design elements that are able to deal with these peaks.
Types of passive house
There are many different levels of passive house design, each with its own advantages and disadvantages. Below is a brief overview of each level and the technologies and design techniques used:
Level 1: Minimum Energy Standard (MES) – Uses heating that is efficient and advanced cooling systems, special windows, and doors that insulate better.
Level 2: Energy Efficiency Standard (EES) – A more restrictive version of MES. It uses the same advanced heating and cooling systems, windows, doors, and walls, and an attic space that is insulated and airtight. The main difference is the water heater that has to be more efficient. We are seeing a transition from gas-powered water heaters to heat pumps that use hot water as an energy source. It is not possible to install this everywhere though so sometimes we have to connect multiple homes to share the heat production.
Level 3: Net Zero Energy (NZE) – The most stringent level of passive house design. It requires a building that is either completely passive or runs completely off renewables such as solar and wind. Houses get an energy score and this is something that buyers can take into consideration as it can provide an indication of their energy bill.
We can expect that these definitions will evolve in the coming decades as new building techniques such as 3D printed houses change the way in which the buildings are being designed and constructed. Building techniques evolve a lot and new materials are being tested all the time.
Advantages of a passive house
The main advantages of building a passive house include:
- Very low energy bills, even during peak usage periods
- No gas, oil, or electricity bills, as all energy is supplied by renewable or highly efficient sources
- Long life expectancy of building components
- Minimal disruption during construction
- No risk of damage from natural disasters
- Very low maintenance requirements, especially considering the house will be nearly maintenance-free
The technologies to do this are still being developed further. It is important to balance the comfort of living in this type of house with the energy needs. We can expect to see big progress on this front in the coming years as new materials and techniques are being developed all the time.
Disadvantages of a passive house
The main disadvantages of building a passive house include:
- Construction is more complicated and expensive due to the increased level of engineering required
- Greater use of energy-efficient technologies, which may have a negative impact on the environment
At the moment passive houses can be more expensive as they haven’t been developed on a larger scale. As local codes become stricter, builders have to spend more time thinking about energy efficiency and how they can optimize this. We can expect that the prices of these advanced materials and building techniques will come down in the years to come. More work is needed before passive houses can become the standard but we are taking leaps towards this.
So, should you consider building a passive house? The answer is yes, if you can afford the higher construction costs and if you are willing to accept some tradeoffs to promote a more sustainable lifestyle.
A passive house should ideally be designed to meet the needs and climate zone of the inhabitants. Do your research online and speak to local builders about passive house designs that can meet your specific needs. We can expect to see a lot of new technologies in the coming years so it will be exciting to watch what happens.