"The German connection"- Ventilation and heating

First (and only) foreign component arrived today after a 3 week journey from Germany. The Mechanical Heat Recovery Ventilation unit (MHRV) will provide the house with a constant supply of fresh air. We choose this particular model as part of the design stage assurance and stuck by our design decision as it provided the greatest efficiency. In this particular application we know that this model will retain 91% of the energy from the extracted air and heat the incoming fresh air so that there is a very small 9% shortfall in the heat to be made up.

The MHRV will process the same volume of fresh air though the house as there is water in Dungannon swimming pool every 22 hours, reducing carbon dioxide levels internally and filtering out unwanted spores and bacteria to greatly increase the inhabitant's air quality.

It is a myth that a Passive house needs no heating system – it requires a very small amount of heating. In this case we will be installing a buffer tank in the hotpress that will be heated primarily by the solar panels on the roof. On winter days when there isn't enough sunlight to heat the buffer tank we will have a small oil boiler in the garage to "top-up" the buffer tank.

The photo below shows the solar panel installed. We trialled 3 brands but settled on this one as it had a better aperture area than its competitors (4.64m²) and according to the climate data relative to Dungannon inputted into our PHPP, we know in advance that these panels will meet 41% of the building's heating needs.

As previously mentioned the MHRV will recoup 91% of the heat in the air leaving the house leaving only 9% to be heated. This will be achieved via the ventilation input air over a coiled hot water heating pipe commonly referred to as a "Wet heater battery" or "post heater" attached to the buffer tank (see below).

When sizing said battery it was noted that it would output 0.3kW to heat the air, essentially this means that to maintain 20°C throughout the house we will be using the same direct energy as 3No 100watt light bulbs, staggering!

The photo below shows the upstairs ventilation configuration.

The photo of the downstairs service void with the MHRV is installed