"Yposkafo," or undercut, refers to a building or part of a building constructed below the natural ground level, with only one visible façade. Its construction involves excavating below the natural terrain, followed by restoring the ground to its original form.

Historically, the use of undercut spaces as residences dates back to the beginning of human civilization, as a natural consequence of the need for protection from the elements. Remarkable examples of cave dwellings have been created in various geographical places, cultures, and times, such as in Santorini, Meteora, Granada in Spain, Cappadocia in Turkey, Matera in Italy, Tunisia, and other locations.

The ideal condition for choosing to create an undercut residence over a conventional one is the steep slope of the terrain. In Greece, many areas feature rocky outcrops that are ideal for undercut residences.

The advantages and benefits are numerous. There is minimal intervention in the natural landscape. "Architectural egos" are by definition rejected in cave buildings, which are perfectly in harmony with their surroundings, and their design is oriented based on the view (a slope usually faces the view).

An important advantage is also the stable temperature of the residence throughout the year. The soil maintains relatively stable temperatures, 12-13°C in mainland Greece and 16-18°C on our southern islands. Therefore, the air temperature inside the residence remains almost stable at 16-20°C year-round.

Having, by law, only one building face open, we almost always create skylights or patios directly opposite the façade. This gives us transparency, a basic principle of bioclimatic architecture, and ensures continuous ventilation and low moisture levels, which is highly effective. As a result, the required mechanical means and corresponding energy consumption are minimized.

We also have increased protection against noise, dust, radiation, and extreme weather conditions. Additionally, fire protection is enhanced. The building has minimal exposure, and with the appropriate choice of materials and insulation, it requires zero maintenance.

But are there any downsides? It depends on your perspective. If the creator or owner, for some reason, wants the building to stand out from afar, this won’t happen with an undercut building. Also, the common question asked when discussing undercut buildings with clients is: "Will I always have moisture problems?" The answer is yes, but only if you choose the cheapest construction instead of the correct one. If the undercut building is constructed with the right materials by specialized technicians for each task, and under the supervision of an engineer, there will be no problems.

I would identify a disadvantage in the legislation, as here too the legal framework is not clear, and there is often disagreement between engineers and urban planning department employees, which leads to disputes, delays, and shifting responsibilities. However, sooner or later, the solution is found.

It is worth mentioning that when we design an undercut house, based on the legislation defined by the New Building Regulations, our permitted construction square meters are doubled. In many cases, we choose not to follow the undercut building legislation strictly, in order to double our buildable area but still create "cave-style" buildings. This way, we can take advantage of all the benefits of undercut housing without the limitation of a single open face or placing the entire building below the natural ground level.