When you think of building a new house you want to make sure you get the best value for your bucks.
Yes, it has to look nice... but it also must be performing well so that it doesn't cost you a fortune in monthly bills.
This aspect depends on how energy-efficient the house will be.
To get to the bottom of this issue, we met a successful Architect and Passivhaus Designer and we asked him to tell us more about energy-efficient buildings.
Here is what he told us...
Kaur Talpsep is a successful Architect based in Tallinn, Estonia.
He is Partner at Kauss Architecture and his Studio employs 9 people.
Kaur's work is oriented to create modern spaces and to satisfy the needs of his Clients. However, in all his creations, Kaur keeps an eye on energy-efficiency.
In 2010 Kaur got a certification as Passivhaus Designer and, since then, he has been taking energy-efficiency very seriously.
Andrea Bronzini: why do you think that energy efficiency is important?
Kaur Talpsep: it was eight years ago when I started paying careful attention to energy efficiency. Energy-efficiency is a basic need.
The first attempt to improve energy efficiency was made when humans started to use furs to cover themselves.
Being naked in a cave, you are losing too much energy. You have to burn more calories and then you have to eat more.
When you cover yourself with the fur, you don't need to eat that much.
Stepping forward tens of thousands of years, we don't need to think about furs anymore... we are now focusing on the cave (the house).
We are building more energy efficient houses.
I think this is a logical way of thinking.
Andrea Bronzini: if you are building a new house and you want to make it more energy-efficient, you need to spend a little bit more on the construction and you're going to save money later.
Is that a wise choice?
Kaur Talpsep: when you're going to shop for a car, as a first thing, you are not going to look how much fuel it burns... but it might be the second thing you look at.
Look and functionalities are tied together and, generally, they are the most important thing.
Energy-efficiency is just a small step behind.
As Architects, we first think about the aesthetics and about how the building is going to be used by the inhabitants.
Power Tip: it is wise to try to minimize the monthly cost of the house, that is the sum of the mortgage monthly-rate and the monthly energy bills.
Minimizing just one or the other does not give the optimal result.
Andrea Bronzini: in your experience do people care about energy efficiency or not?
Kaur Talpsep: on the first meeting they say "yes, we do care about energy efficiency... we want to have a zero-energy-building".
You should know that the most energy efficient housing would be a house without windows and that is extremely unpractical.
So, during the design process, Clients realize they have also other needs so they let go a bit of the focus on energy-efficiency.
In general, it is never only about saving energy. Everyone wants to find a compromise between the openings (windows or glass facade) and energy efficiency.
Power Tip: glass is less energy efficient than wall - by far!
When you design your own house, keep in mind that windows you should be made of a nice size
but not too big... otherwise you're gonna spill energy out.
Andrea Bronzini: let's talk a little bit about why we should choose wood over bricks or concrete or other materials.
Kaur Talpsep: I think building materials are very much connected to region people are living in.
I have been living in Spain for one year and the wood was very scarce there.
Traditionally they have other construction materials. They use mainly concrete.
Coming to North, let's say to Eastern Europe, bringing the concrete to the construction site and building only out of concrete wouldn't be a wise choice.
If you want to build in the middle of the winter, probably the only choice you have is to do it with other materials (water in the concrete freezes in winter, making it more difficult an expensive to use build in concrete).
Every kid knows that stone is cold when it's cold outside. So you need to insulate it.
Going back to the wood, there are several kinds of constructions one can use.
Today, the traditional log buildings are for the countryside houses.
People do use it but it's worth considering only for a holiday house.
So basically, the wooden frame technology is probably the most efficient way to build today. This is because you can pack lots of insulation within the thickness of the wall.
One could also build a house out of bricks and then put a wooden structure outside and insulate it in between... this is a very common way of building. However, thinking about environment and economics, it probably is the stupidest way.
One could use a timber-frame main structure and finish it with bricks outside. This is much more energy efficient and cost-effective.
So, yes, building with wood is a wise choice if you are considering smart ways of insulating the house.
Andrea Bronzini: if a client comes to you and tells you - "I want to build a wooden house" - what are your suggestions?
Kaur Talpsep: I think it's a wise and environmentally-friendly choice.
There are questions you have to ask: how are you going to build the house in wood?
is it going to be log building? ...no, right?
is it going to be a balloon frame building? ...well, it could be yes.
is it going to be cross-laminated timber frame or panel building? ...that could also be.
When thinking about building with wood and about the traditional methods of building, there are obstacles you have to overcome.
The main obstacle is the human factor: the person who's building on-site.
When building on-site, things are quite error-prone.
First of all, you have to find the right crew. Then you have to check if they do follow the project and if they follow the procedure of applying the different layers of the materials.
In the end, when I'm thinking about building a balloon frame house, I only consider producing it in a safe environment, under controlled circumstances.
I would only go with factory production.
Andrea Bronzini: today, everything we own comes out of factories. Car, computers, phones, whatever machinery we use, it comes from a factory... but houses?
Houses generally do not come from a factory and if we say we got our house from a factory, people ask: how can you do that?
We can... and the more we do it, the more we can specialize in this and the process looks more and more different from the carpenter work on site...
Kaur Talpsep: yes, the factory worker is going to work every day and every day he does the same thing in the same place. He has the tools always in the same spot and he practices the same procedures every day. So he becomes highly specialized and highly skilled.
This is not what usually happens on the site.
Andrea Bronzini: let's spend a few words to describe what happens instead when construction is done entirely on the site...
Kaur Talpsep: it is more difficult to control what is going on on-site.
Without talking of possible structural problems coming from human-error, coping with the weather might be the biggest challenge.
Once the frame of the house is up, rain-protection barriers should be installed before attempting to install insulation... but in reality this does not always happen and it is difficult to monitor the process... you should always be on-site.
If the insulation gets wet, it loses its insulating properties and if the moisture is not removed it will remain in the walls. With time, wet areas will grow molds and this is very harmful to the health of the inhabitants of the house.
Andrea Bronzini: how long it takes to build a house entirely on-site?
Kaur Talpsep: it used to take years. Now it is typically a one-year process.
For comparison, a factory-made house goes up in about five days or so. This means that even if the weather is not wonderful, you can still cope with it and have the house built without damaging the insulation.
If some humidity gets inside during the assembly process, it can be removed when the house is closed.
It is sufficient to warm up the house and install ventilators that will push out the humid air.
It is very important that the insulation doesn't get wet.
Another important thing is air-tightness.
Modern energy-efficient houses must be air-tight. Air-tightness is achieved with plastic membranes installed on the interior of the house.
When you build on-site you have little control over the way workers install those membranes.
Instead, when the house is produced in a factory, the membrane is just another layer on the element and workers take great care when installing it.
It is all part of a process. It is easy to control.
When you install the elements on the site, you just need to control the taping of those few overlapping panes. It is much less hassle.
Prefabrication is a very efficient way of building houses.
Andrea Bronzini: when we build a house in the factory, we have a lot more design than when we make house entirely on site.
Kaur Talpsep: yes, on-site basically you give instruction to workers and they have just the blueprint of the house. They look at the blueprints and they figure out how to put things together.
In factory production, every element has its own detailed drawings and things are never left to the opinion of workers. Workers are always told what to do.
Also, quality checks are built in the process and so each component of the house should be produced to a higher standers. The entire house should be better.
Andrea Bronzini: yes, this is why here on katus.eu we focus on wooden prefabricated houses.
Their quality is generally excellent and they offer better energy performance for the same size of walls. The price is not that different.
The price of a prefab wooden house is generally lower than a brick house or a concrete house that has the same energy performance. On top of that, the timber-framed wall is way less thick.
This is true also for walls built with cross-laminated timber.
Kaur Talpsep: yes, CLT offers a better structure but then you still have to add the insulation.
CLT is good if you have to go high (tall buildings, more than 3 floors). If you stay low, you don't need to use CLT, unless you want to have it for aesthetical purpose or other reasons.
In the end, the key takeaways from this talk with Kaur are:
- timber-framed construction if the most energy-efficient type of construction because it allows packing the insulation inside the wall, resulting in slimmer walls;
- size of windows should be carefully considered if one wants to save energy;
- prefabrication is highly recommendable because it delivers more quality and it avoids mistakes;
- air-tightness of prefabricated buildings is better than in building built on-site because the design and the assembly are executed with a detailed and clear process.
If you need more information on any of the points above or you want to discuss it further, feel free to reach out to us.