What is the fundamental purpose of a building?
Buildings serve several needs of society – primarily as shelter from weather, security, living space, privacy, to store belongings, and to comfortably live and work. A building as a shelter represents a physical division of the human habitat (a place of comfort and safety) and the outside (a place that at times may be harsh and harmful).
As you can see, comfort is fundamental to the purpose of a building. So why do we find it so hard to ensure our buildings are actually comfortable? Why does our ‘world-class’ architecture still fail to provide comfortable buildings to live, work, learn and play in? (Besides using far too much energy and emitting far too much CO2!)
The Passivhaus Standard is known as the world’s foremost building energy efficiency standard. And it is that, but it is also a comfort standard. After all, what is the point of a building being energy efficient (or low carbon for that matter) if it compromises the functionality and comfort of the people who use the building? Passivhaus buildings provide exemplary comfort for the occupants by maintaining a healthy comfortable temperature, by being quiet, by having fresh air and by being draught-free.
Comfort is a reason to Love Passivhaus!
Love Passivhaus: Comfort – Warm / Cool
The Passivhaus Standard is a “fabric-first” standard, which means that the building must be insulated to an optimum level for the climate it is located in. Contrary to what is sometimes thought, passivhaus doesn’t require a set U-value (or R-value) for walls, floors and roofs. The U-value is dependent on what climate the building is in, more insulation is required in extreme climates and less insulation in milder climates.
Having an optimum level of insulation ensures that the inside spaces stay warm in cool seasons and cool in warm seasons. Importantly it also means that the inside surfaces of the building fabric (the walls, for examples) maintain a comfortable temperature and never feel like cold radiators!
Being a “fabric-first” standard means passivhaus also requires higher performance windows and doors than is typical in most locations. This means that in the UK for example triple-glazed windows are required. However, in milder parts of New Zealand for example, it is possible that high performance double-glazing is suitable. The result is the same as for insulation – comfortable inside temperatures and comfortable surfaces on the inside of the glazing. You will no doubt be familiar with the cold radiant effect of a typical window in winter if you live in a cool climate like I do in the UK – you don’t stay near it for long!
Keeping the temperature so stable inside does mean the sun needs accounting for; external shading will often be required. Overheating is risk that mustn’t be forgotten, even in relatively cool climates like the UK. Good passivhaus design and modelling will ensure the right shading is included to prevent excessive solar gain in summer.
The Passivhaus Standard requires that the building fabric is airtight. This ensures that the heat inside the building doesn’t unintentionally escape out through small gaps and cracks in the construction. Even a tiny gap can compromise the insulation performance, never mind the moisture risks it introduces.
In most climates, the Passivhaus Standard requires mechanical ventilation with heat recovery. This ensures that the warmth inside the building isn’t thrown out the window when fresh air is needed. The ventilation system recovers the heat from stale outgoing air. This heat is used to warm up the fresh air being brought into the building. This way fresh incoming air arrives at 16°C or more, certainly not at the freezing outdoor winter temperatures!
More than the sum of the parts
All this adds up to excellent indoor temperatures that are more easily controlled by the people. Did you ever notice that with ‘natural ventilation’ you have no choice when it comes to comfort? (Except in perfect climates!) If you want fresh air in winter, you get cold when you open the window. And in summer when you want fresh air, you get hot!
There are also fewer fluctuations in temperature to contend with. Of course it gets warmer and cooler depending on the sunshine, the heating system and people’s activities. But the fluctuation is comfortably low.
Similarly there is very low stratification of internal temperatures. This might seem like a minor detail, however, having cold feet (for example, with an unheated concrete or tile floor) and a warm head can be very uncomfortable!
With passivhaus, being a comfortable temperature is more than just the number on the thermostat!
Love Passivhaus: Comfort – Quiet
We often experience to a certain amount of background noise and learn not to notice it. The Passivhaus Standard offers a quiet indoor experience that often catches people by surprise. Even builders on site get a surprise when the windows are installed and suddenly the internal building site becomes markedly quieter!
This is due to the quality of the building fabric. The high performance windows in particular keep out far more sound than typical windows. No more traffic noise or rowdy neighbours invading your privacy. And of course, when you do want to connect with nature and hear the birds and the wind, you can open a window (or door) for as long as you want to.
Another important factor is the quality of the ventilation system design and installation. In non-passivhaus buildings with mechanical ventilation, there are often complaints about noise. Either the system itself is noisy, or unwanted sounds transfer from one space to another. The Passivhuas Standard requires that acoustic attenuation be provided as part of the ventilation system so unwanted sound isn’t transferred between different spaces through the ventilation ducts. And the ventilation equipment must also be suitably quiet so that it isn’t obtrusive. This is critical with such high performance fabric where outdoor sounds barely intrude.
With passivhaus, being comfortable includes enjoying the quiet!
Love Passivhaus: Comfort – Fresh Air
In most climates, the Passivhaus Standard requires mechanical ventilation with heat recovery as mentioned above. (Here is an exception to this in a comfortable climate in Mexico.) As also mentioned above, this provides exceptional thermal comfort – fresh incoming air is always warmed to a suitable temperature.
The ventilation system in a passivhaus building also provides comfort in the form of consistent clean fresh air. While you may not have considered it before, we actually don’t ventilate our buildings enough a lot of the time. This is particularly the case where we rely on ‘natural ventilation’. So often there is a reason not to open a window or trickle vent – maybe it is too cold outside, or too hot, or too windy, or too noisy! The result is we don’t have enough fresh air indoors. It gets stale and polluted by a variety of gases, including CO2 from our breathing, odours from human activities and VOC’s being emitted from materials and finishes in our buildings.
The ventilation system in a passivhaus building solves all of these issues. It provides slow moving, fresh filtered clean air without noise while at the same time removing indoor pollution, stale air and unwanted smells.
And importantly the ventilation system gives people control over their air! The system can be turned up to provide more air when there are more people (‘Party Mode’?) or turned off it its actually not needed, and of course windows can be opened for extra air!
With passivhaus, being comfortable includes enjoying fresh clean air at all times!
Love Passivhaus: Comfort – Draught-Free
When it comes to unwanted draughts in a building, draught-stopping in obvious places, such as around windows and doors, is usually the solution suggested. In a passivhaus building this is inherently taken care of the by the requirement for the building fabric to be airtight. Not only does this prevent unwanted heat loss, it also prevents unwanted cold draughts coming in.
However, beyond airtightness there are also two other key aspects of the Passivhaus Standard that keep a building draught-free.
The first is the high performance windows. As mentioned above, this keeps the surface temperature of the windows at a comfortable temperature. If this were not the case, in winter the cold glass would cool the air that came into contact with it. This in turn would cause a cool downdraught of air from the windows. Traditionally this has been combatted (in the UK at least) by locating radiators underneath windows – as the cold air falls, it meets the rising warm air from the radiator and theoretically mixes to a comfortable temperature. While this might mitigate the effect to some degree, it is much better to solve the problem in the first place, as the Passivhaus Standard does!
The second is the mechanical ventilation system with heat recovery. In a passivhaus building the ventilation system provides fresh incoming air at a comfortable temperature. This way the fresh air won’t feel cold, nor will it cause any draughts due to a temperature difference with warmer indoor air. The fans in a passivhaus ventilation system also operate at low speed so the movement of the incoming air is barely noticeable. No unpleasant indoor breeze!
With passivhaus, being a comfortable means no draughts!
Love Comfort: Love Passivhaus
For a building to be certified to the Passivhaus Standard it must meet all the comfort requirements as well as the energy efficiency requirements of the standard. There is no point in a building being energy efficient if it isn’t also comfortable and suitable for people to occupy and use. Shelter, and therefore comfort, is the primary function and purpose of a building.
The comfort that passivhaus provides is more than just good internal temperatures. The standard ensures buildings can be affordably kept at comfortable temperatures, are quiet, are supplied with plentiful fresh air and are draught-free.
Unfortunately for many people around the world these qualities are a luxury they may never experience. However, for those of us privileged to live in circumstances where shelter and comfort is readily obtainable, these qualities are what we should expect from our buildings. Our health depends upon these aspects of comfort. People living in cold damp uncomfortable homes contribute to our high asthma rates. It is unacceptable that so many people in the UK and New Zealand particularly continue to suffer unnecessarily from asthma in this day and age.
Architecture in the anthropocene needs to deliver radically energy efficient buildings. Comfort and health must not be compromised in our mission to reduce energy consumption and CO2 emissions though. The world needs more radically energy efficient buildings that provide excellent comfort. Passivhaus buildings.
This blog post is part of a series of posts on reasons to love the Passivhaus Standard – in contrast to the tongue-in-cheek post ‘10 Things I Hate About Passivhaus‘ which you may have already read. The #LovePH series was prompted by the inaugural South Pacific Passive House Conference and Trade Show taking place in Auckland, New Zealand, over Valentines weekend 2015. I was privileged, both as a Kiwi expat and as a passivhaus architect and enthusiast, to be invited to give a presentation at the conference, on behalf of Architype Ltd where I work.
Please join in and share on social media what you love about the Passivhaus Standard using the hashtag #LovePH.
For more posts on reasons to ‘Love Passivhaus’ and to learn more about passivhaus related topics, please subscribe by email at this link.