While temperature and humidity are the two factors that affect indoor comfort directly, the way they behave depends on a few construction details of your house.

These details are often overlooked by Architects and Engineers.

So, how can you make sure you get them right?

Here is how you do it...

Yes, it is frustrating.

You thought that paying a professional to design your house should be enough to guarantee excellent results on every aspect of construction and quality.

In reality (with a few exceptions for truly remarkable professionals), when you hire an Architect you get a nice and functional house but not necessarily a high-performing one in terms of comfort and energy.

Your house can be only as good as the people who worked on its design, therefore your main concern should be on hiring competent professionals.

But how can you tell the difference between someone who just does the job and someone who really takes care of every aspect?

It is not easy... impossible - I'd say - if you do not have a technical background yourself.

What if I give you a few tips to guide you on what you should keep your eyes on?

Once you know the important details that should be considered carefully, you can bring them to the attention of your Architect/Engineer and you can understand whether he/she is up to the game or you need extra support to get everything right.

Sounds good?

So let's begin...

First thing first.

In case you feel like you need extra support where do you turn to?

In the article "Your House Manufacturer: The 5 Benefits of Choosing Early", we explained that one of the benefits of partnering up early with a Producer is that he can help you spotting design and technical issues. This is exactly the case we were talking about.

The good news is that this extra support does not come at an extra cost (how awesome is that?).

The Manufacturer you choose should be able to comfortably discuss all the 5 points below and to propose solutions to improve your existing design, within the limits of your budget.

NOTE: if your Manufacturer is not able to address the following 5 points, well... you probably picked the wrong one. You know what you should do.

1. Air-tightness

In a modern building, air-tightness is the single point of failure... therefore it deserves careful attention.

With the advent of modern mechanical ventilation machines, it became possible to regulate the amount of air a house exchanges with the outdoor environment. This is done automatically by the machine in an effective and energy efficient way.

For the system to work, the house must be  and air-tightness is achieved by installing a tiny plastic film (or membrane) inside the construction of external walls and roof.

The membranes of different wall elements are taped together to form an envelope (a giant plastic bag) that encloses the entire indoor volume.
This is called air-tight layer.

But why you want to enclose the living space in this giant bag?

Being in control of the amount of air leaked from (and voluntarily introduced in) the house brings the following advantages:

  • reduced energy loss;
  • increased indoor air-quality;
  • reduced condensation risk inside the insulation of external walls / roof.

Even if you are not particularly sensitive to energy consumption problems, you should care enough about the quality of the air in your house. In the long run, air-quality plays a big role on your health and on the health of your family.

The biggest harm to air quality comes from the mold that might develop inside the external walls due to unwanted condensation of humid indoor air.

If the air-tight layer leaks air towards the outside, condensation will occur and mold will form inside the insulation, leading eventually to the rotting of the insulation material.

Although the process takes years, a faulty air-tight layer will result in your family breathing unhealthy mold.

Disgusting, right?

This is why getting the air-tight layer right is so important.

The correct installation of the membranes and taping is tested with a pressure test.
To make sure the air-tight layer is working fine, the pressure test should be executed once during construction (before finalizing the interiors) and once the house is fully ready and delivered.

Double checking the integrity of the air-tight layer is so important because any leak is virtually impossible to fix without taking apart part the portion of wall or roof around it.



  • ask your Architect and Manufacturers how they are going to take care of air-tightness;
  • make sure your Manufacturer has records of measures executed on previous buildings and that those records conform to the Norms;
  • make sure pressure tests are scheduled at some point in the construction process, either by you or by the Manufacturer.

2. Windows quality

Windows give light to the indoor space but also keep the cold out.

When it comes to indoor comfort, the most important function of windows is to ensure a uniform distribution of temperature across the room.

The glass and the frame of the windows are exposed on one side to the cold external environment. External walls are also exposed but they contain a lot of insulation.
The result is that the interior surface temperature of the external walls and windows will be different.

If this difference exceeds 3° Kelvin, you will feel "cold" coming from the window.

Of course you don't want that... right?

So it is important to install excellent windows.

Today materials are so good that wood and PVC perform essentially the same.
Some aluminum profiles are also well performing but generally way more expensive than PVC and wood.

When it comes to glass, given the small price difference between double-glass and triple-glass, we warmly recommend using triple-glass.

Triple glazing will guarantee higher temperatures on the internal surface of the wall and this will ensure no condensation (no mold) and no cold air falling down to the floor.

The phenomenon of cold air falling from large windows is what causes "cold feet" for those who live in the house.

As a rule of thumb, the larger the window, the better the glass should be.



  • ask your Manufacturers to provide windows with good frames (low U-Value);
  • ask your Manufacturers to provide windows with excellent glass (low U-Value).

3. Quality and type of insulation

The insulation material of your house is important because it keeps the cold out in winter and prevents the heat coming in during summer.

It is recommendable to use the best type of insulation you can afford - with regard to its insulation properties, measured with "lambda" values.

Standard insulation has lambda 0.37.
The unit of measure of lambda is W/(mK).

Modern insulation materials can have lambda values of 0.33 which is over 10% more performing than the standard 0.37.

Polyurethane insulation has lambda in the order of 0.22, which is a whopping 40% increase in performance!

Of course polyurethane insulation is much more expensive, so you should evaluate which is the optimal tradeoff between energy saving and cost of the structure.

Besides the energy aspect, one should care to use eco-friendly insulation materials on the indoor side of the air-tight layer.

This is important because particles from the insulation materials are free to move in the indoor space.

You definitely do not want them to end up in the air you breathe!

Using eco-friendly insulation in the indoor spaces is a seldom-adopted (although quite inexpensive) fix that will ensure way better air-quality for you and your family.



  • always ask your Manufacturers a price offer with standard insulation (the first offer, to get a feeling of the base price);
  • ask a revised offer with better insulation material (lambda 0.33);
  • ask for formaldehyde-free insulation on the indoor side of the air-tight layer (usually 50mm).

4. Energy Performance

This is a no-brainer.

The better your house performs from an energy point of view, the more uniform temperature you'll have on the inside and the less money you'll spend to heat the building and to keep it warm.

Good energy performance is achieved by making the building envelope as insulated as possible.

The building envelope is composed of external walls, windows, roof, foundation.

Part of the energy performance is taken care of when choosing the best windows you can afford. However, it is important to focus also on the other components.

While your Manufacturer will suggest you the best solutions for walls and roof, the solution for a good foundation should come from your Architect (since Manufacturers usually do not deal with foundations).

Always make sure you build to reach the best energy performance you can afford.

5. Walls sturdiness and Soundproofing

Finally, the house is a space you should be able to enjoy and utilize in any way you want.
To ensure this is true for all the indoor areas, you should pay close attention to the structure of the walls.

You are going to need to hang things on walls, so you need them to be very robust.

A double layer of gypsum will NOT do the job, let alone a single one. You really cannot hang a shelf securely on a gypsum wall.

The best construction for the interior side of a wall (be it external or internal) is a chipboard + a gypsum board.

The gypsum board behind the gypsum gives the walls robustness and ensures you can easily and firmly screw things on any wall of the house.

This is a simple and affordable solution that will save you headaches in the future.

The chipboard in the wall also guarantees the wall does not get broken when accidentally smashing heavy objects on it and it also delivers better soundproofing performance.

To maximize soundproofing, all internal walls and ceilings between floors should also contain insulation material.



  • always ask your Manufacturers to quote walls with chipboard behind the interior gypsum;
  • make sure they use insulation in the interior walls and ceilings. Note that this insulation should preferably be formaldehyde-free since it is inside the living space.

A Home Your Friends Will Envy

Following the suggestions above you will be able to build a home like no other.

Getting everything right might increase the cost of the build a little bit. However, when you consider the long-term benefits you get from living in a healthy, clean, warm environment... it is well worth the money.

NOTE: do not be scared of spending a few thousand euro more on Quality, Comfort and protection of your health. This sum will be paid out over the period of your mortgage and it will probably increase your monthly payments by a few euros only!