Highlights of our JAHUS projects

Background info: I realized that I have been so eager to get started with this blog that I forgot to describe what we’re trying to do in our house. Included below are the highlights of our JAHUS project:

Step 1: We asked specialists about where to start to get the most “bang for the buck” (“bang” for us = lower electricity usage). They recommended to replace old windows and doors and add more isolation in the attic – and closing all the old air-valves (minimum 2 per room). These are the actions that will give the best immediate effect (and it will give the same effect for the people living in this house in 2050).

Step 2: Because the house is better isolated there is no longer sufficient recirculation of the air. We therefore needed to add a ventilation system. It was a pleasant surprise to understand that the latest technology available on the market can recover 90% of the energy in the air before it is “blown” out of the house. This is obviously a better solution than a lot of air-valves that lets 22C air straight out in the cold outside air. (In Norway we say that the old way is “heating for the crows”…).

Step 3: The ventilation system does not add heat (or cool down) to the fresh and filtered air it pushes around in the house. And even though the above mentioned activities dramatically reduces the energy lost to the outside air – we still need to add heating (and cooling in the warmest summer months). We have not removed the electrical heating we have in all rooms, but we are adding a heatpump that is 3-4 times as efficient as traditional electrical heating (1KW gives a minimum of 3-4KW of heating).

Step 4?: Specialists also say that you can save 20%+ by implementing a central control system for lights and heating in the house. We have asked for proposals, but there seems to be issues associated with the integration of our ventilation-system and heatpump. This last step is in status = To Be Decided.

Decision point
There are multiple versions of heatpump to choose from:

• Air-to-air: these are the cheapest and most widely used.
• Air-to-fluid: used for new buildings or old buildings with a distribution-system for heating already in place (heated fluids).
• Fluid-to-fluid: requires drilling a well in the garden (typically 200m deep) and this system has the same requirement for an in-house distribution system. Into the well you insert a special fluid in a closed loop with the heatpump. After having pulled energy out of the fluid and transferred it to the loop inside the house – the heatpump sends the cooled fluid back into the loop (to be warmed by the higher ground temperature 200m down in the well).

We have an old house without a distribution system for heated fluids, and the only economically feasible solution for us was “air-to-air” heatpump. One of the challenges of a single air-to-air heatpump in a relatively big house is the distribution of the heat in winter and cold air in the summer. Hot air is lighter than cold air and hence tends to move upwards, and the opposite is true for cold air – so how to get cold air to the first floor in the summer and warm air to the ground floor during winter? The ventilation system we’re installing takes care of this (according to the specialists).

Note: the project is being implemented in a climate close to the polar circle, but in warmer parts of our planet – people face the same (but opposite) challenges. The outside temperature is very different from the comfort temperature inside and A/C systems are installed to fix this problem. You can either use a lot of electricity do drive the A/C at full throttle – or you can do like we did: isolate and add a ventilation system that recovers most of the desired energy (in this case negative energy = cold air).