Design Process
Design of a 150 m² house
Today we are talking about the design of a 150 m² house, a spacious size yet tailored to the needs of an average family, which allows us to have between 3 and 4 comfortable bedrooms without sacrificing the benefits of a passive house.
On several occasions, we have addressed house design based on surface area; today, a house is inconceivable without being efficient, and the fact that we design a larger or smaller house will have direct implications for its energy consumption.
A key aspect in the design of a 150 m² house will be the choice of land, its size, and its orientation. To have a house that does not consume energy, we need the sun to help us heat the spaces naturally. Therefore, if the land does not allow for good sunlight in most spaces, we must use energy, either by generating it on the site itself through renewable systems or by connecting to the grid to meet the energy demand.
A suitable plot for the design of a 150 m² house
Depending on a series of characteristics that we will list below, the land can represent a better or worse starting point for the design of a 150 m² house. While many issues can be solved through good design, it is also true that everything is much easier if we know how to properly analyze the pros and cons of a plot to make a decision with all the facts on the table. The idea is to tilt all variables in our favor to enjoy not only an efficient and environmentally friendly house but also a comfortable one.
Minimum surface area
To guarantee the construction of a 150 m² house design, a good plot should have a minimum area. Typically, for land outside the urban center—that is, not located between party walls—the minimum surface area we usually recommend is about 500 m² to have a minimum of freedom in the placement of the dwelling and good sunlight.
A plot smaller than 500 m² will not allow us to enjoy outdoor spaces if it leaves us no margin for the placement of the house. We must take into account that most municipal regulations require us to set back between 3 and 6 meters from both neighbors and the street facade (except for urban dwellings); therefore, on small plots, once we subtract the mandatory square meters for setbacks, the location of the house becomes very restricted.
Morphology
Morphology refers to the shape of the land, with a rectangular or square geometry being the most optimal for making the most of the available square meters.
On a rectangular plot, the priority will, of course, be for the longest side to have good orientation. This is not always possible on sloping land where the short side is often the one with the views and the sun.
Triangular plots are the most limiting for distribution, as applying regulatory restrictions and subtracting the required separation distance from the street and neighbors often leaves an excessively limited surface area for locating the house.
Surroundings
Another characteristic we must observe is the surroundings of the land we are going to purchase for the design of a 150 m² house. We must assess potential neighboring buildings and their height, as they can hinder sunlight to our house, potentially limiting our possibilities for capturing light and generating energy naturally.
Regarding the surroundings, at Slow Studio we have a complete checklist to perform, from potential high-voltage lines to proximity to schools; you can find the checklist before buying land at this link.
Slope
Sloping land complicates the relationship with the terrain; if we are building a house, it is normal to seek a good connection with the outdoors in most of the dwelling, but if the slope is excessive, this direct relationship can become complicated.
However, it is not all downsides, and sloping plots are often more affordable than flat ones. On sloping land, we can apply certain implementation strategies that improve both the relationship with the terrain and the bioclimatic performance of the house, such as semi-burying the ground floor so it rests against the earth—an element that serves as a thermal buffer with a constant temperature of about 20 degrees Celsius throughout the year.
Furthermore, we must consider that a poorly oriented slope makes solar incidence on our house very difficult. In cases where we doubt if the slope might be poorly oriented—that is, with north, northwest, or northeast orientations—the ideal is to visit the land in winter when the sun hits more horizontally, around 3 or 4 in the afternoon, which is when we will want our house to be heating up naturally. If the sun does not reach the plot, then it has a poor orientation.
Regulations
For the design of a 150 m² house, as we have seen, a minimum land area of about 500 m² is recommended; this is because construction regulations for any plot require us to separate from neighbors and the street by 3 to 6 meters.
What other regulatory issues can limit the design of a 150 m² house?
In general, the main aspects to check are the footprint and the buildability of our land. The footprint is the percentage of square meters we can occupy on the ground relative to the total area of our land—that is, if we take an aerial photo of our house, how many square meters does it occupy? Buildability is the total square meters counting all floors of our dwelling.
In the case of a 150 m² house design, we can, for example, distribute the entire house on a single floor of 150 m², in which case we will have occupied and built 150 m²; or distribute the dwelling over two floors of 75 m², in which case we will be occupying 75 m² and building 150 m². The maximums are established by the regulations of each local council.
Other issues to check regarding regulations include, for example, knowing if we are allowed or required to have a parking space inside our plot, if there is access to all services (electricity, water, fiber optics, sanitation, or even gas, though it is not eco-friendly), or if we are required to replace cut trees or have a water tank.
Distribution in the design of a 150 m² house
The first question clients ask us when they know their budget fits the design of a 150 m² house is how many bedrooms will fit. Here the answer will be: it depends.
It depends on the square meters we want our bedrooms to have. If we follow the technical building code, minimum room sizes are somewhat tight, and we could reach 4 or even 5 bedrooms if they are singles. For an average family with comfortable standard rooms, we would aim for 3-4 proper bedrooms, including doubles and singles.
It is all a matter of priorities; we can prioritize a maximum number of bedrooms and study spaces that meet minimums, or opt for a solution that allows for a smaller number of larger, more spacious rooms, as well as a generous living room and kitchen. In any case, the second solution will be easier to distribute and allow for sunlight conditions or cross-ventilation, which are highly valued in passive architecture.
In summary, for some families, 150 m² is the minimum necessary surface area to have 3 or 4 bedrooms or study spaces. For others, 150 m² can mean 3 very large, spacious bedrooms and a wide living room and kitchen.
In any case, at Slow Studio, we always remind you to maintain a balance between your needs and the requirements for efficiency and a healthy home.
Any house project starts from a maximum budget that we do not want to exceed, and in this sense, it is important to decide whether we want to go for maximum square footage or allocate part of the budget to achieving greater efficiency or even zero consumption.
Single-story 150 m² house design
The distribution for the design of a 150 m² house must take into account the orientation of the rooms based on their use and the user’s needs. The main factors of its design are that the dimensions of the spaces align with the user’s needs and that the floor plan distribution is comfortable, practical, coherent, and with an architectural morphology integrated into the surroundings.
Distributing the entire program on one floor reduces the number of square meters dedicated to circulation and accessibility and simplifies the structure, reducing its cost. Furthermore, many families choose this option, if the land allows, with the aim of gaining comfort, especially considering a house that is for a lifetime and must also serve us as we get older.
In general, we can place daytime use rooms in areas that receive light during the day, such as the south, east, and west. In contrast, service rooms, storage, or simply nighttime use areas that do not benefit as much from natural light can be located in northern zones.
There are many options for the design of a 150 m² house. A first option would be to invest in bedrooms to achieve greater flexibility of use or capacity for more users, in anticipation of wanting to expand the family or regularly sharing the space with family and friends; in this case, we can choose to include up to 4 bedrooms, including doubles and singles.
A second option would consist of opting for very spacious common areas and a kitchen, with a large south-facing window of about 40 to 60 m², and reducing the number of bedrooms to just a couple of rooms with a bathroom and a toilet.
Finally, the hybrid option, and therefore the most common, would be to distribute the 150 m² into a medium-sized kitchen-living-dining area, connected to a small multipurpose study that can be a bedroom if needed, a double suite-style bedroom, and two smaller bedrooms for children; the size of all of them can vary, and we must take into account the size or number of bathrooms we need for dimensioning.
Two-story 150 m² house design
In the case of opting for two floors, a decision that is usually conditioned by the characteristics of the land itself, we must know that we will gain and lose certain things. Naturally, we will lose some comfort, but depending on the land, we will gain in sunlight, potentially achieving two south-facing facades. In the case of a two-story distribution, we will generally locate the daytime areas such as the living-dining room and lounge on the ground floor, and the nighttime areas such as bedrooms and private family bathrooms on the first floor.
In the design of a two-story 150 m² house, we will often find that splitting two 75 m² floors will be very tight, especially after subtracting circulation and stairs; therefore, in these cases, the most common approach is to locate a ground floor of about 100 m² and an upper floor with the suite, for example, of 30 m² plus circulation and stairs.
As mentioned, segregating two distinct zones on different floors allows us to gain privacy, as well as achieve better views and sunlight on the upper floor.
Furthermore, as this is an aspect that depends directly on the size and characteristics of the land, we also find the possibility of having no choice but to add a floor. Following a similar scheme to the previous one, service, storage, and accessibility spaces are usually assimilated on the north facade in the form of a vertical and structural core. This block will allow us to close off where there is no need for capture, thus generating the necessary privacy in contact with the street/neighbors.
We must not forget that a second floor gives us the possibility of creating terraces, as well as working in section on steeply sloping land, allowing for greater contact with the terrain.
Examples of 150 m² house designs
Having seen the different types of distribution, let us now look at specific cases of implementation for houses of approximately 150 m² that we have carried out at the studio.
House in Monte el Pardo
The House in Monte el Pardo, measuring 150 m², is located in Torrelodones, Madrid, and represented a significant challenge for Slow Studio in integrating the lifestyle of an adventurous family. The main premise consists of making part of the house independent so it can be rented out during periods when they are not in Madrid.
In terms of distribution, the entrance is on the first floor via a walkway that resolves a steep slope in the first few meters of the plot. On this upper floor, we find a suite and another bedroom with a bathroom, with plans to divide it into two single bedrooms. This is the floor that can be completely independent from the lower floor.
The lower floor houses the living-dining area, the kitchen, and a small study that can be converted into a bedroom, all in complete relationship with the outdoors.
On the other hand, we find two courtyards on both sides of the house, positioned to guarantee cross-ventilation for all rooms. Additionally, both can be covered or uncovered so that, depending on the time of year, they can serve as additional ventilation in summer or as winter gardens that also help regulate temperature and humidity inside naturally.
House in Badalona
The House in Badalona is located in that city and encompasses a complex program consisting of a home and a recording studio. Similarly to Carlos and Verónica’s case, by sharing private and professional life on the same plot, the need arises to make the recording studio independent on the upper floor.
Thus, we decided to separate the two programs with a courtyard that serves as access to both and is reached through a porch that also functions as a parking area.
On the east side, we located the recording studio, just above the entrance porch, consisting of a double-height volume with excellent acoustic insulation and whose interior is completely empty to allow for the creation of different scenarios according to the client. The studio relates to the exterior in the northern area of the dwelling, maintaining the family’s privacy in the south-oriented garden should both uses coincide.
On the other side of the courtyard, we located the dwelling, which, with the aim of relating as best as possible to the terrain, we distributed over two floors: on the ground floor, with direct access to the outdoors and maximum opening to the south, the daytime areas: living room, dining room, and kitchen plus a double bedroom. On the second floor, with better views but no outdoor connection, we located the suite.
The energy efficiency system, as in most of our projects, is based on an inertia wall that accumulates heat from large south-facing openings, airtightness, and high insulation that help us maintain heat in winter. In summer, solar protection and cross-ventilation, together with the thermal inertia of the walls, contribute to maintaining a cool environment without the need for air conditioning.
House in Santa Maria de Palautordera
The house located in Santa Maria de Palautordera proposes a simple and effective scheme: an L-shaped house where the daytime areas were located on one side and the nighttime areas on the other, articulated by the access and service area.
After much consideration of the initial scheme, we decided to propose improvements that involved swapping the location of the daytime and nighttime areas to achieve a larger south facade in the daytime areas and a better relationship with the outdoors, as well as adding a second floor to provide more space to the ground floor and achieve views of the Montseny on the first floor, where the master bedroom will be located.
With this improvement, the living room, dining room, and kitchen have a better relationship with the outdoors on the long side of the plot, making the most of the sun. Additionally, the bathrooms are relocated to the northern zone to improve the thermal buffer of the coldest facade.