You might also be wondering if there is enough light in a mole house, whether it's cold inside or, on the contrary, if it overheats in the summer. Are heat pumps or air conditioning necessary? As the requirements for the energy class of houses tighten, questions about the necessity of ventilation with heat recovery arise. Let's take a closer look at the experiences of owners living in mole houses.
From time to time, clients opened their homes to us, for which we are very grateful. However, we come across the privacy of the owners. During inspections, people often asked similar questions about heating and ventilation, which leads us to summarize the questions. Join us in looking at the responses from two clients as well as from the founder of the mole house and judge for yourself to what extent a mole house will suit you.
A few common details about mole houses: By 2020, none had air conditioning, none had a heat pump or heat recovery in the standard sense. All mole houses have at least 500mm of soil on the roof, all have large windows, and only every tenth one needs a skylight (not a light tube, but a regular skylight through which you can observe the stars). The orientation is to the north, southeast, south, so it varies according to the diversity of the nature in which the houses are embedded, and of course, according to the requirements of investors.
Owner Juraj: Mole house on a flat surface, southeast-oriented, passive ventilation = natural heat recovery. Shading with a canopy. Materials: fired brick, wood, stone, concrete, clay plaster, and wooden floor, waterproofing against water pressure.
Owner Adam: Mole house on a slope, north-oriented, kitchen and terrace to the west. Electric heating, passive ventilation = natural heat recovery. Materials: regular plaster, cork floor, sleeping area underground, living room with kitchen with a regular roof. Ytong, concrete, wood, waterproofing against water pressure.
Owner Martin: Mole house founder. Southeast orientation, without shading, without passive ventilation. Two-story mole house. Materials: clay plaster, hemp facade, wooden partitions, concrete, waterproofing against water pressure.
Names have been changed, article authorized by clients.
VENTILATION question - How do you ensure clean air in the Talpa House?
Do you have to open windows often?
Once every 0.5h
Once every 1h
Once a day
Other…
Answer Juraj: We ventilate when cooking since we don't have an extractor hood. Air in the house is exchanged naturally - passive heat recovery.
Answer Adam: Other.
Answer Martin: Once an hour when visiting. Otherwise, once every 2-3 hours. In winter, the air outside is dirtier than indoors, so we don't overdo it. Not every neighbor burns dry and clean wood.
How long does it take to clear the air in the house after COOKING, using the TOILET, or SHOWER?
5 min
15 min
30 min
Other…
Answer Juraj: It varies in each room.
Answer Adam: 5 min.
Answer Martin: 5 to 10 min. Sometimes we forget and close it only after an hour. That's how long it takes for us to feel a temperature change in the house with open doors or windows.
HUMIDITY question - Ventilation is also related to humidity. Do you have a dry nose feeling? Do your clothes dry out in the house?
How long do clothes stay fragrant in the closet? Do they not get damp and stale?
1 week
2 weeks
4 weeks
Other...
Answer Juraj: Clothes? We don't have that measured. The optimal humidity in the house is 50%.
Answer Adam: Clothes? We have a dryer. Fragrant clothes last for 2 weeks.
Answer Martin: We don't know dry noses at all. The humidity in the house is balanced between 45% and 65% all year round. We have few clothes, so we change them often. I don't know how long they stay fragrant.
COOLING question - Do you have a shelter in front of the house?
Which direction is your house mainly facing?
South
West
East
North
Answer Juraj: Yes, we have a shelter. South-facing house.
Answer Adam: No, we don't have a shelter. We oriented the house to the north.
Answer Martin: We don't have a shelter yet. But we plan to because we have scorched lawn in several places from the windows.
How do you cool your burrow house?
Open windows at night
No need, not necessary
I have air conditioning
Other...
Can you tell the average temperature in the house during the day, or when you return home from work, or over the weekend from the terrace?
Answer Juraj: No need to cool. The house cools or warms by opening and closing doors, as family members go in and out, etc.
Answer Adam: No need to cool.
Answer Martin: We open windows at night. It does a little, especially when we have them open all day to hear the child sleeping outside under the tree. The temperature stays up to 25°C. In winter, we expect to use about 1 cubic meter more wood when the window is often open.
HEATING question - How long have you been living in a burrow house?
Answer Juraj: 3 years.
Answer Adam: 9 months.
Answer Martin: 2 years for us and 3 years for tenants (brother and random) before that.
Do you prefer a temperature between?
20-22°C
around 25°C
around 28°C
other...
Answer Juraj: 22°C is the optimal temperature for us. Up to 23, during the day we also function below 22.
Answer Adam: No need to cool. 20°C
Answer Martin: In summer during the day up to 25°C, it can drop to 22-23°C in the morning. In winter, we maintain 21°C during the day and drop to 19-20°C at night.
Do you feel a difference in temperatures between rooms vs the living room?
Up to 3°C
Up to 5°C
Up to 10°C
Other…
Answer Juraj: Up to 3°C. e.g., if the kids are in the room with the door closed, it feels warmer in the room.
Answer Adam: —
Answer Martin: up to 1°C. When I concentrate, I feel the difference. But I don't usually notice it. That's why I estimate the difference up to 1°C.
How much do you need to heat in a burrow house? Who in the family is sensitive to cold?
Answer Juraj: We heat minimally, more like tempering.
Answer Adam: We reheat. The husband is sensitive to cold.
Answer Martin: My wife is sensitive to cold. I would prefer a temperature of 19-20°C in winter. My wife is comfortable from 21°C. When it's sunny, we only heat water for bathing. When it's cloudy, we also have to heat the house.
UTILIZATION question - What do you grow on the roof?
Once a day
Once a week
Once a year
Not at all
Other...
Answer Juraj: There is a lawn, nature-rain waters it.
Answer Adam: We grow on the roof, I water it once a day.
Answer Martin: The green roof itself with meadow grass is watered by rain. The part where we have a garden is watered with cleaned water from the wastewater treatment plant, and it is done continuously with drip irrigation. Since we have low water consumption, we also have less cleaned water. Therefore, we plan to have a well for the garden and lawn in the future.
If you were to give one piece of advice to those interested in a burrow house, what would you recommend?
Answer Juraj: If we were to build again, we would build a burrow house. Ours suits us, we wouldn't change anything about it.
Answer Adam: Don't hesitate, I don't regret it, I know it was the right decision.
Answer Martin: Pay attention to the quality of details. People judge only what they see. The quality of living for a 2-5 hour visit is difficult to recognize. However, they will notice a cheap detail right away. A cheap building looks cheap. A quality building has a higher value in case of sale. Make a pantry. It's still necessary in the 21st century. It might replace a refrigerator, which has a one-third share in household consumption even in AAA efficiency.