Last Updated 1 year by Lukas
In this article I’d like to share my experience of owning a Passive House. I’ll also describe what I would have done differently if I had known what I know now. Together we will explore what are reasonable expectations of a Passive House. How to avoid the pitfalls I’ve fallen into, and how to get the most enjoyment and benefit from your new Passive House. As in the previous article, which described systems I had personal experience of, we will now go system by system and evaluate them. This article is based on almost three years of using, learning and fine-tuning the Passive House.
What are the benefits and drawbacks of systems used inside passive houses?
Recuperation of energy, heating, water system, heat pump
- System parameters
- Recuperation unit from Atrea R-5 series type RA5
- Water tank 425 l with flow-through water heating. It’s used to hold energy, heat water and heat air through recuperation unit
- 65 l water heater installed on the output from main water tank 425 l
- Outside heat pump unit from Sinclair ASGE-12BI with R-32 coolant
- Water softener with 20 l of katex medium
- E-vodnik system with flooding prevention, water consumption monitoring and inflow, water filter
- Advantages
- Recuperation automatically brings you fresh air and keeps as much energy as possible inside the house. It simply uses exhaust air to heat/cool fresh air from outside. It’s also able to detect high concentration of CO2 and start ventilation/recirculation of indoor air based on that.
- A 425 litre water tank acts as an energy battery and split unit for the external heat pump unit. It can store energy in ‘technical water’ and use it later when needed to either heat air and dilute it through the recuperation unit into the house. Or it can heat water flowing from outside to provide a hot shower. It can also store extra energy from a solar system.
- With the 65 litre ad hoc water heater you can set a low temperature in the water tank. This allows you to either use the heat pump in the most efficient way or create more space for storing energy from the solar system. At the same time, it doesn’t reduce your comfort as this amount of water is more than enough for a shower or a small bath. Also this amount of water is heated up to 60-65 degrees in a reasonable time (up to 15-30 minutes depending on the heating power).
- The external heat pump unit allows you to absorb energy from the outside air and transfer it into heated water in the water tank. The system is also able to switch valves and use the outdoor unit to cool air directly during hot summer days. This is very beneficial in a house that tries to keep the internal environment as isolated from the outside as possible from an energy exchange point of view.
- The water softener, together with the filtration and E-vodnik system, ensures that internal appliances are protected from limescale. It also makes cleaning much easier. It also gives you an overview of water consumption and you can close the main valve remotely. Inflow filters are very good at keeping your internal water systems free of small particles from outside. These can damage your valves or get into the water you drink.
- Disadvantages
- It’s a very complex system with lots of moving parts. If the owner wants to be able to fix it, fine-tune it. It will take a reasonable amount of time to understand. Otherwise it’s maintenance, solving basic problems can get very expensive. Of course, as the system improves comfort a lot, maintenance costs are something to be expected.
- A heat pump can usually only work effectively up to 50-55 degrees Celsius. Unfortunately, in the case of a 425 litre water tank with flow-through heating of outside water. This is not enough to fill standard baths with sufficiently hot water. This is because the performance of the heat pump depends on the outside air temperature (in the case of air-water systems). It usually takes 60-120 minutes for the outdoor heat pump unit to raise the temperature of 425 litres of water by 10 degrees. This can be very limiting for bathing lovers.
- Technical water from the water tank is also used to heat the air through recuperation. If you set the temperature above 52 degrees (as high as the external heat pump unit can go). You have effectively turned the system into an electric heater. Because above 52 degrees heating is done by 3 phase heating rod and that’s not very efficient way how to heat water (factor 1:1 compared to heat pump with in average 1:3. In other words, 1 kWh consumed produces 3 kW of heat energy into water).
- An extra 65 l water heater will consume extra electricity. It’s important to compensate for this with a solar system and to invest in an efficient water heater.
- To prolong the life of your internal appliances and keep them working at maximum efficiency. You need to invest in a water softener (if you have high levels of limescale in your water). For example, Katex water softeners require regeneration after some time with salt water. You need to consider the availability of the drain
- If the system is improperly installed, it can have a huge energy consumption during the cold winter days.
- Changes / Improvements to the system over time
- Installation of Katex water softener with inlet filtration
- To keep appliances free of limescale and working efficiently
- To prevent solid particles (larger than 50 microns) from entering the water system.
- Installation of an additional 65-litre water heater for hot water on demand
- To increase comfort, it’s able to reheat water to 60 degrees by the time a person finishes showering, bathing.
- To allow further system optimisation, the water tank is kept at a low temperature to store as much energy as possible from the solar system.
- Fine-tune the parameters to run the heat pump as efficiently as possible to avoid huge electricity consumption on cold winter days.
- Save money by limiting electricity consumption
- To extend the life of the heat pump compressor
- Fine-tune parameters to store as much energy from the solar system as possible
- To save money by reducing electricity consumption
- To increase the self-consumption of the solar system as much as possible
- Installation of Katex water softener with inlet filtration
All in all, if I forget all the hours and long nights I spent fine-tuning and learning the system. And the many failures I had to endure before I learned how to connect it to other systems in the house. To run the system in the most efficient way. I’d be happy to buy something similar again. I really like the in-built monitoring tools within the system, the large number of parameters you can fine-tune and of course the ability to store a lot of energy in the water. I’d change the external heat pump unit to a more powerful one, increase the size of the water tank and let the system run on its own automatic control. At the moment everything is controlled centrally by Loxon, but unfortunately it is not always possible to integrate Loxon without compromises. I’d like to emphasise the importance of taking a step back and looking at all the systems you want to install in your home and assessing whether it’s even possible/feasible. This kind of thinking exercise will save you a lot of trouble in the future when it’s hard/expensive to change things.