Architect Elrond Burrell provides answers to a few common questions that people have about the Passivhaus standard.
Interview with Elrond Burrell
As part of Ben Adam-Smith's video work, podcasts and meeting with other self builders, he is often asked questions about the Passivhaus standard that he doesn't know how to answer. He recently took the opportunity to put those questions to Elrond Burrell.
Born in New Zealand, Elrond has been working in the UK for the last 18 years. As well as being a qualified Architect and Associate at Architype, he writes a plain speaking and successful blog about Passivhaus, which has a global following. Before he returns to New Zealand we caught up with him to tap into his Passivhaus expertise, and also find out what his plans are for the future.
Is it necessary to have a heating system in a small Passivhaus?
This will depend on the specific heating demand of the project. It is possible on a very small project to get away with just a portable electric heater, bathroom heated towel rail or similar.
A risk of doing this is that if the house is sold or has different occupants they might not be fully aware of this and find that they do get a little cold on rare days of the year. Elrond suggests a more robust approach is to just put in a very small heating system.
Another thing to consider is that heating is only one part of the equation in terms of power consumption, and actually in a Passivhaus building, providing the hot water can quite often be a bigger heating load than providing the space heating.
“And so you tend to design a system that can provide all the hot water needs for the year, and have enough capacity in that to provide the small amount of heating that you might need in the cold days of the year.”
Why might you not want the heat source to be incorporated into the ventilation system?
Firstly, air only has the capacity to carry a certain amount of heat. Water and solid surfaces can carry and radiate much more heat than air can. If you need more heat than the air can provide then you can't do it all through the ventilation system.
Secondly, you need fresh air all of the time! In order to guarantee good quality, fresh, filtered air all year round, then you need the ventilation system running all the time. You don't necessarily want the heating system running all the time though. There may also be times when you want more heating than the ventilation can provide. Although there is some logic in combining them, they are two quite separate systems in a way.
To avoid overheating, can you integrate a cooling system into the house?
The Passivhaus standard allows for 15kW annually of heating per m², and likewise allows for the same of cooling if required. In a relatively mild climate like the UK you shouldn't need cooling if you're designing the building well. In much warmer climates you would expect that in a very efficient Passivhaus you may have a small amount of cooling, the same way you have a small amount of heating. Like the heating, it can be provided by the ventilation system or separately through a radiant or other cooling system.
In a Passivhaus project you wouldn't put something in as a ‘just in case' measure, because using the Passive House Planning Package (PHPP) software you can very accurately design and predict how the building will perform.
“So you shouldn’t be putting in stuff just for the eventuality that it might be needed and you should be designing it to get it so you don’t have that need.”
Does it make sense to have mechanical blinds to give you a sense of control?
More commonly used in Europe and the US than they are in the UK, Ben says that some of the people he comes across like to have the mechanical blinds to give them an extra bit of control. Elrond suggests that it is important for people to feel in control of their environment and that they can modify and change things if they wish to. They shouldn't feel that they're living in a house which they're not allowed to touch or interact with, so if people feel strongly about having the blinds then they should go with it.
Something to be wary of is if they're built within the window it can be an expensive operation to fix or replace them if something goes wrong.
“So it’s not something specific to Passivhaus but it’s more the approach a lot of people that come to Passivhaus want to take is really simplification and trying to avoid moving parts and things that might go wrong at a later stage.”
The power consumption and how they get detailed and built into the building will also need to be accounted for in the Passivhaus modelling.
How adaptive can the house be in terms of comfort?
Regarding temperature, this will come partly come down to the design of the building. The upstairs rooms are likely to be a little warmer so personal preference about whether to sleep in a cooler or warmer room may be a contributing factor to the design. And if heat is being delivered by the ventilation system then wherever the air is being delivered is going to be warmer than where it's being extracted from. If you're heating through a radiant rather than ventilation system, then these can be located in areas where you would want to feel warmer.
Another thing about adaptive comfort, which is in the Passivhaus Institute guidance, is ensuring that all occupied rooms have got windows that can be opened.
When Elrond returns to live in New Zealand in the near future he will be continuing with his blog at elrondburrell.com. He has also set up a new company, VIA architecture, and will be offering a ‘PHeasibility' service.
It is important to Elrond to embody his own personal values in the work he does. “So not just what looks like sustainability but what really counts in the details and in the putting it all together.” VIA architecture is based on the idea “that particularly using the Passivhaus standard we should be able to use architecture to transform the quality of peoples’ lives and so it’s really a process of using architecture to get to a good outcome. Whether it’s a really healthy, comfortable home, or a school or a business or what-have-you. And so architecture is kind of the process to get there rather than the end product in itself.”
The PHeasibility service involves Elrond taking early designs and running them through the PHPP in a basic way, before a commitment to employ a Passivhaus designer has been taken. It will give an indication for self builders or architects without Passivhaus experience, as to what might be involved, taking into account constraints and design, for the building to achieve the Passivhaus standard. It will look at the key aspects which determine if the fabric, orientation, windows etc are going to be of the required standard. They will then be better informed as to whether to pursue the certification.
Find out more about PHeasibility
Visit the PHeasibility website
Special offer: subscribers to Elrond's blog can get Pheasibility for £495 instead of the standard £745 if they book it in September or October. To subscribe to the blog (direct link to subscribe: http://elrondburrell.com/hph_subscribe) and then send an email to PHeasibility@elrondburrell.com
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The Hub update
The Hub has now been going for a year and we'd like to thank the founding members who have put their faith in us. We're always looking at ways to improve what we are offering and in the coming months we'll be trying to make the modules even more step by step and easy to follow.
Our second case study is now under way, the Buckinghamshire Passivhaus, headed up by architect Janet Cotterill from CTT Sustainable Architecture. The project first started out as a retrofit so find out why it didn't continue that way, and went on to be a new build.
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