Tag: low energy buildings

HPH299 : Is mechanical ventilation just something else to go wrong? – with Ben Adam-Smith
Ben Adam-Smith shares his own experience of living with a mechanical ventilation system. While he’s clocked up a few error messages on the unit and had more problems than most, he explains why he wouldn’t want to go back to natural ventilation.

MVHR is a key component of low energy buildings

In case you’re wondering what MVHR is, well, it stands for mechanical ventilation with heat recovery.

As buildings become increasingly airtight, a good ventilation strategy becomes all the more important.

But there’s a clever twist: by controlling the ventilation you can recover the heat when you want to (transferring it to the fresh incoming air).

Hopefully that’s clear, but if not we made a documentary about airtightness a few years ago!

Since this documentary was made I have moved into my own Passivhaus.

Error messages are warnings

I am a big fan of MVHR (pun intended) but that doesn’t mean I’ve had the best relationship with my MVHR unit.

I’ve had 3 sets of errors on the machine in the two and a half years I’ve had it.

The first errors might have been in connection with a silencer that was retrofitted a year after we moved in. I suspect the machine was clever enough to notice something had changed. The errors resolved themselves!

About a year later, an external pressure message cropped up a number of times.

The fan status readings on fan speed two which should be 200m3/hour are:
Supply fan – Speed 550rpm, Duty 15%, Flow 93% ( a noticeable drop in air flow)
Extract fan – Speed 1900rpm, Duty 48%, Flow 0% ( air flow can be detected from the extract air valves when a piece of tissue is held up to them )

Error messages can be reset

Interestingly, these errors can be reset while you’re investigating the cause… but they usually return, even if that is weeks later.

Apparently there was a known issue with the humidity sensors on my particular unit. This was changed and again it was business as usual.

However, at the beginning of the year a new error cropped up!

Nobody likes seeing a flashing red light on their control panel because it means something needs fixing (or at least investigating).

At this particular point we’d been getting night-time temperatures between -2C and -5C, which is the coldest we’ve experienced since we built the house.

When the temperature warmed up a little I was able to reset the error and everything would return to normal (or until I could get the machine looked at).

However, that trick didn’t work the next day.

The machine completely died and I couldn’t get it to come back on. There was also a light burning smell inside the house.

I had a couple of concerns at this point:
- How long will it be until I get my machine back up and running?
- Might I get a build up of mould somewhere in my system if I can’t get it fixed soon?
Fortunately when it comes to mould, I was quickly reassured by my friends in the know.

So, now whilst the problem was investigated we had to survive without the machine.

With no MVHR running, we resorted to opening windows!

Not that I’d choose to do this experiment but it was quite interesting to see the impact of living in a Passivhaus with no MVHR running.

Firstly, the house remained nice and warm inside (the insulation has gone nowhere). Perhaps the heat wasn’t as even; I don’t know. But it wasn’t a terrible experience.

It was however, a right faff to have to open the windows every few hours… not to mention the heat we must have wasted… and the family complaining at having the windows open when it was freezing outside.

Perhaps the most interesting impact of no MVHR was the instant lingering smells. My wife noticed that each room had its own smell! And it was definitely harder to shift cooking smells.

Eliminate the simple stuff first

On a chat with Steve Clarke at Green Building Store trying to diagnose the problem, we double-checked that power was getting to the unit.

Embarrassingly I hadn’t even checked the trip switches. In fact, we’d managed to cover them up with a shelving unit so that I’d forgotten they were even there!

With the machine humming to life, I had a massive sense of relief. Whatever the issue is it’s not quite so urgent when the system is at least on.

The preheater needs to be replaced

It didn’t take long to diagnose the problem (the burning smell was the preheater working for the last time) but British wisdom of leaving the EU meant the new preheater took several weeks to get here.

The warranty period on MVHR units is typically 2 years

For an essential item for Passivhaus dwellers, this does seem short.

The clock also starts ticking when you buy it.

Mike Coe, the self-builder behind Portree Passivhaus, bought his unit in advance and subsequent delays have meant it will already be out of warranty.

My own unit was out of warranty, too, but the manufacturers kindly supplied the new part free of charge.

I installed my new preheater!

With Steve Clarke from Green Building Store on the phone, I was expertly talked through what I needed to do.

Buying through a company with good customer service was a great move.

We’ll have to wait for more cold weather to check it has done the job.

‘MVHR needs to be as reliable as a fridge’

I was interested to see whether other people had had trouble with their units and so I posted up on social media.

I don’t believe many Passivhaus owners have actually had problems, which is a good sign. As Fionn Stevenson says ‘good quality assurance is essential’.

Andy Simmonds, Chief Executive of the AECB, stressed it is such an important piece of kit. The emphasis needs to be on durability, reliability and repairability.

He likened an MVHR unit to a fridge.

Having bought a new fridge when I built the house I have noticed that even fridges have got more complicated.

In the past it’s normally the plastic door seal that has failed before anything else, but on the new more complex models water dispensers get jammed on and ice trays freezer up, and don’t get me started on the plastic water filters!

I would not go back to ‘natural ventilation’

Despite the inconvenience of investigating different error messages, my MVHR unit has never stopped! Yes, I was a bit slow to check the trip switches, but if there’s a next time I won’t make the same mistake.

If the machine is still operating, you haven’t got a big problem

If your machine is not working at all – i.e no ventilation whatsoever – then I would really be looking for a speedy repair.

As with anything in life that breaks, it normally takes a little while to fix it.

So it would be lovely to have the option of a 24-hour repair service in the years to come.

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March 24, 2021
HPH264 : Your forever home lifestyle – with Mark Siddall from LEAP

Mark Siddall from LEAP explains his framework the ‘Forever Home Lifestyle’ and how he uses it with his clients.

Interview with Mark Siddall

Mark Siddall is an architect with a passion for designing low energy buildings. Recently he’s taken a look back at his last decade of projects and thought about the things that clients have asked for and what their cumulative thinking is. He’s used this as a starting point to come up with his ten point framework for a forever home lifestyle.

Preston Springs Passivhaus

Contentment and character

The first step on Mark’s framework is to think about contentment in the right ways and in different timeframes.

When we think about contentment it is usually in terms of an actual design and, largely the character of the design. That can be broken down into the interior and the exterior. Externally there might be constraints by planning related considerations, and internally it’s more about budget and aspirations that can transfer into elements of style.

“The sense of wellbeing that comes from being content is incredibly important and it means different things in different contexts. It’s an opening into a deeper level of conversation that will allow people to make a more robust appreciation of what they actually want.”

Convenience

Once emotional constraints have been considered, then there’s convenience. This covers the room layout, the accessibility around the house, and the way that it supports and compliments our lifestyle. This means thinking about the flow, the circulation spaces, the function of the rooms, the furniture and fittings that come with that.

When Mark goes through the process of developing a brief, he will conduct a survey of what people do and don’t like about where they’re currently living, to determine how important a particular factor is and what the implications are.

“They’ve obviously selected to live there; they’ve made those choices and its informed their understanding. So, if they want to then move to the next level and improve their quality of life, how can we take the best of what they’ve got and then top it and make it even better?”

Control

Having control over your own comfort is very important, and ties in to an emotional criteria. That can be down to opening or closing windows, controlling heating systems, creating a healthy environment through air quality, noise levels and controlling sunlight levels to prevent overheating.

Confidence

This is about how confident a self-builder / homeowner can be about what they’re seeking to achieve. Mark says that his building performance evaluation provides evidence-based reassurance to support and justify decision making. Using PHPP is part of that process for Mark, as without it you wouldn’t get the quality control that is required for delivering buildings that the performance predicted. He says there are no definitive answers from this, but that he is there to provide guidance to help clients make their own informed decisions.

Community

Community is important when putting your 25 or 50 year framework in place. It is about thinking of whether you want to live in isolation, or within a hamlet or town setting for example, and considering what kind of support you might need in the future or can offer yourself. That can also lead to thoughts about co-housing or community-led housing which might compliment different lifestyles.

Connection

A natural progression is to then consider connection and accessibility of amenities and looking ahead to whether you will be living in an area that can support your needs in older age. These thoughts then inform what kind of site you’re looking for, and whether you’ll be able to walk or cycle safely, or if it’s a walkable distance from bus stops taking you where you might need to go once driving is no longer an option. Mark says clients will often have an emotional connection to a site because of the remote location or wonderful views, without thinking about how well it will serve them in the future.

Larch Corner interior

Futureproofing

This looks at getting the right kinds of spaces and also thinking about how things might change over time. It also ties in with low-energy housing and Passivhaus, where energy bills can be fairly inconsequential, thus offering a level of financial independence once a mortgage has been paid off.

There is sense in designing the building so that in the future it could be adapted if mobility was a problem, by making level flooring, having the right things in the walls ready in case handrails are needed, and having access through the house for wheelchairs or walking frames.

Financial Peace

As well as thinking about the freedom from energy bills, this is concerned with budgets and how to stick to them.

Even before Mark is instructed as an architect he will do a piece of work using his experience of previous similar builds to give a rough range of costs. This can give the basis for conversations to be had around what might be achievable in terms of what the size and nature of the house might be, before even getting into the design stage. It is however only a starting point.

“That means that informed decisions can happen before there’s a design taking place. And that’s really important. That way we understand what we’re designing because the budget informs the brief incredibly and we’ve got to design within those budgetary constraints.”

“I can provide a bracket somewhere between this and that, at a very formative stage. There are things that I can do as an architect that can help to stack the odds in our favour of it being more cost effective in terms of the compact form and thinking about things like that, but at the same time, there’s that reconciliation and there’s always the changing marketplace which means that we always can find that there is going to be some movement and further conversations to have. It’s not done once and then never looked at again.”

Faithful custodian

Mark sees himself as an architect and also custodian of the built environment. He says that sustainability can seem broad and rather distant, but once his clients see themselves as custodians too they have positive and constructive conversations that develop and benefit their designs.

“So, as a custodian, we’re thinking about how we can address climate change, how we can reduce carbon emissions, how we can live more sustainably, how we can help repair and remediate damage to the ecology and biodiversity. And how we can then start to use the buildings that we design collaboratively; how they can then start to do something restorative to improve the quality of life and at least impact less than may have been the previous case.
There are all sorts of different perspectives about what that might mean and how it relates to their lifestyle, and that’s all fruitful conversation which helps enrich my understanding and I can then pass that on and enrich somebody else’s.”

Abundant free time

This asks how the house will support and provide a framework for having an abundance of free time and improving quality of life.

In simple terms it can be about providing opportunities to work from home and avoid a long commute. It also thinks about diet and fitness and keeping physically and mentally active.

Find out more

Visit the Forever Home Lifestyle website

Find out more about LEAP

Follow Mark Siddall on Twitter

Transcript

Download a transcript of the interview with Mark Siddall

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September 25, 2019
HPH227 : What’s the best way to build an airtight structure? – with Paul Jennings
Air leakage expert Paul Jennings looks at how best to achieve that all important airtightness when using particular construction methods.

Interview with Paul Jennings

Paul Jennings is an air leakage expert with over 25 years experience. In our previous interview with him he explained how to achieve airtightness in low energy buildings. He also appeared in our documentary “The Future of Housing – and How Airtightness Can Help”, taking a look at housing construction quality and building performance to see how they could be improved.

For this podcast, he looks at some of the issues with achieving airtightness in different construction types.

Cross Laminated Timber (CLT)

Paul recently tested a bungalow that was built using Cross Laminated Timber. The airtightness is essentially in the timber, and in this bungalow there were up to 8 laminations in each of the panels. The roof was a sandwich panel with layers of lamination, insulation, and more laminations on top. With the panels being larger than standard OSB boards, there is less taping involved. Each panel is also very strong, and strengthened further when screwed together. The taping goes where the panels butt up to each other, around windows, ventilation ducts, sun pipes etc. Once you have taped to the timber you have airtightness.

Paul is starting to think that there is no need for a membrane on the outside. The CLT doesn’t meet insulation values but he thinks it’s perhaps easiest to insulate it externally and make it airtight on the inside.

Structural Insulated Panel Systems (SIPS)

Paul has experienced very good results with SIPS panels, which he feels have the potential to be very airtight. So far he hasn’t seen anyone using the airtight OSB as one of the faces of a SIPS panel system, which he thinks could improve it further.

He explains there is a difference in results depending on whether foam is injected into the pre-made box, or whether a piece of foam is cut and put into a section of wood which then has sides added. The latter won’t be as airtight.

SIPS panels can be a problem on site if they get saturated with water as they take such a long time to dry out, and the airtightness tapes do not adhere properly.

Masonry Construction

Masonry construction ticks the box of being a system that normal builders are used to building, where most materials can be sourced from a standard builders’ merchant. Paul offers Denby Dale Passivhaus as a great example of this.

Paul explains that any construction with a cavity in, is a weakness for airtightness. If air can move laterally it can get around things and leak where you wouldn’t expect it to. He prefers a masonry build that has a masonry wall which is ideally wet plastered for airtightness on the inside, with insulation and render on the outside.

“Because at that point, you have to have a continuous hole from the inside to the outside. You can’t have a hole through the inner leaf, then air moving in which way it likes in a cavity and then coming out somewhere else. It’s more robust for airtightness.”

Paul points out that almost every masonry build has a timber frame roof, so as soon as you’ve opted for masonry construction you’ve doubled the number the number of build forms in your house anyway.

Paul emphasises how the more complicated a build is, the harder it will be to achieve the airtightness. There is greater scope for people on site getting confused, doing the wrong thing or not checking details properly.

Modular construction

This isn’t a widely used construction method in the UK but there are increasing numbers of companies trying to develop it. The benefits of this method are that production has less of an issue with weather, shortage of trades people etc, than for on-site construction. The ones Paul has seen have been generally at a prototype stage with initial positive signs and great potential. He believes they will have to be built to be incredibly robust, as otherwise they wouldn’t survive being craned on to a lorry, driven to the site and craned off again.

One of the big advantages of modular construction is there is less time spent on site, which means less financial impact from weather delays, and less overheads on things like site supervision, site cabins and toilets.

Airtight OSB is gaining in popularity

The trend that Paul is seeing at the moment is that membranes are losing out to the airtight Oriented Strand Board (OSB) and, for refurbishment particularly, to blowerproof paint. The most popular he currently sees in the market, and which he thinks are proving to be very successful, are the Durelis and the Propassiv.

“At the same time, the refurbishment market is a bigger market than the new build market. We need to tackle refurbishment and we need to tackle it better. And we’re not. We’re learning lessons but really we’re taking our time over getting it and I don’t think we can afford that time.”

Choose the right tape for the job

Choose the right manufacturer, and the right tape. For example, don’t try and use 50mm tape to cover a gap of 60mm. Choose one that is wide enough for the gap.

Paul believes the two best products for airtightness are produced by SIGA and Pro Clima. But no matter how good the tapes, most important of all is how well they’re applied.

Plan early and get advice from the experts

“You really want to get your designing done early, get your planning done early and then don’t mess with it. Because every time you change it, there will be unforeseen consequences. Usually those will be things that make your airtightness worse or harder at least.”

Paul encourages self builders to take advantage of the Passivhaus Open Days and talking to the people who have built them. There are also the AECB and UK Passivhaus conferences that people can attend and find out more about the network of experts.

“There are networks of people and a lot of them are very committed people. They give their time, they give their energy and they often don’t charge as much as they should for it, because they believe in it.”

Find out more

Visit the website of Design Buro

Transcript

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September 19, 2018

HPH191 : Key decisions that impact on the sustainability of a house build – with Lloyd Alter from TreeHugger

Lloyd Alter from TreeHugger shares his advice on what we should be prioritising as 21^st century self-builders.

Interview with Lloyd Alter

We catch up again with Lloyd Alter, whose work as an architect and a real estate developer led to his interest in modern building methods. He blogs for the website TreeHugger and also teaches sustainable design at Ryerson University in Toronto, Canada. Previously, Lloyd’s talked to us about worldwide trends in green designs.

Don’t measure value in pounds per square foot

Lloyd says that size will be the most important decision about a house build because so much relates to it. While building small may be preferable for sustainability, he acknowledges there are various problems to overcome.

Some contractors may refuse work on smaller houses, or argue that a bigger house is better value. Lloyd warns against buying more space than you need. A bigger house may cost less per square foot but that is a dangerous criterion for measuring value. He explains, “It will cost you more per unit of area to build smaller but the aggregate, it will still cost you less.” Operating and maintenance costs will also be less with a smaller dwelling.

House size may be dictated by the plot

Re-sale value can force a self-builder into a larger project. Often it’s the land that really has the value, so there’s a judgement to be made about the right sized house for the size of the plot. And Lloyd points out that putting in services costs the same regardless of house size, potentially making it harder to recoup costs on a smaller house.

By-laws can, in some instances, prevent small homes being built. For example, Lloyd explains that some North American municipalities fix minimum square footages to guarantee a minimum tax return.

Balance location with lifestyle

Lloyd recognises the dilemma for self-builders who want to minimise their carbon footprint but can’t afford the expensive land located close to facilities.

Low energy buildings can reduce environmental impact, and changing habits can also mitigate high-energy consumption. Someone Lloyd knows – who lives 9km away from town – cycles, uses a hybrid car when he has to drive, minimises shopping trips and avoids ordering things delivered by truck. Lloyd himself tries to balance his many air miles by cycling and keeping his house at “incredibly low temperatures”.

An independent expert will help you design for sustainability

In a poorly planned house, you pay more for a poor living experience. Lloyd mentions one self-builder who incorrectly fitted insulation and this decision threatened to destroy his house.

For Lloyd, an architect should “help you get to the essentials and put the essentials together in the most efficient, satisfying and beautiful way.” He sees this as directly linked to building sustainably: “The key to sustainability is living with less and the key to living with less is to have it designed properly.”

To choose an architect or builder, Lloyd suggests going to see their work and spending enough time with them to know that you like them, they understand you and that you can understand what they’re saying; clients shouldn’t have to deal with what he calls “Architectese”!

Simplicity should be designed into the house in the first place

So-called “smart homes” are fashionable but Lloyd is wary of unnecessary complexity that adds cost and needs maintenance. “My attitude is I like a dumb home!”, he says, citing the Passivhaus as a good example of this. Using less power means no need for a smart thermostat or a complicated solar panel system connected to the grid. “The house takes care of itself,” he says.

Another reason to keep house design simple is to accommodate changing technology. Low voltage LED bulbs have practically eliminated the problem of lighting load and our technology increasingly runs on low voltage DC wiring. Lloyd envisages future houses solely using DC, so any high voltage electric systems fitted now should be kept accessible.

As different building elements last different lengths of time, Lloyd’s advice is to prepare and keep things simple. “Put as little of it as you need in. Because at some point, you’re going to have to redo it anyway.” Homeowners should be able to access, change or fix any systems in the house:

Element of your property	How long it may last
Land	Forever
Frame of your house	500 years
Cladding	200 years
Windows	100 years
Plumbing	50 years
Electrical	20 years
Mechanical systems	10 years

Fabric first is fairer as well as simpler

Lloyd believes it is unreasonable to simply aim for “net zero carbon”, stating, “We have to use less, period. Even if we’re trying to offset it with energy from sun or wind.” Thus, investment in domestic energy production is another trend that Lloyd mistrusts. Compared to the huge amount of energy used for transport, he describes solar panels on roofs as inconsequential. “We should be going after the big things. And that’s efficiency, not solar panels on the roofs,” he says.

He remarks that policies of domestic generation of electricity disproportionately favour people who have south-facing roofs. Someone without a roof or who can’t afford solar panels will pay more for their electricity, meaning the poor end up paying for the grid. A fairer system in Lloyd’s view would be for everyone to live in houses that are built to a higher standard and use less energy.

Preferred methods of building continue to change

Lloyd teaches a sustainable design course and the content can change every year. Ten years ago, he taught about spray foam that seals and insulates efficiently, but we know now this foam contains unhealthy flame-retardants and some don’t even work below three degrees Celsius. The current insulation trend is for low carbon cellulose, although Lloyd prefers rockwool.

On the subject of new building techniques, Lloyd says, “I’ve become very conservative as I’ve gotten older.” He sees people who want the “latest new thing” demolishing existing houses on highly sought-after plots. This discourages building really good quality houses because “they don’t seem to be building them forever anymore”.

Construction methods can be more suited to specific locations

Building with “brick and block” gives thermal mass, holding heat in the day and releasing it at night. Lloyd says that this principle works well in the high Arizona desert, with hot days and cold nights. In less extreme climates such as the UK it is less effective, and making bricks, concrete and mortar releases a lot of carbon dioxide before construction even begins.

Homes should be comfortable, safe, secure and resilient

A self-build should bring comfort and happiness. Just because it’s environmentally friendly doesn’t mean you have to suffer!

Considering our changing world, Lloyd advises self-builders to prepare for power outages, provide some storage for water and food, and build high enough and not in the middle of a flood plain. He adds that if you have to cycle to get milk, then make sure you can actually do it! “That’s what a home is supposed to be,” he says. “A place of security and comfort. That’s what we should all be striving for.”

Find out more

Visit the website of TreeHugger

Follow Lloyd Alter on Twitter

Transcript

Download a transcript of the interview with Lloyd Alter

Please connect with me

Subscribe, rate and review the podcast in iTunes
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September 25, 2017

HPH188 : What are Paragraph 80 builds and how do they work? – with Richard Hawkes from Hawkes Architecture
Richard Hawkes from Hawkes Architecture tells us about the exceptional circumstances in which planning for rural new builds may be granted.

*Since recording this podcast, the government has updated the National Planning Policy Framework. ‘Paragraph 55’ (or ‘Para 55’) policy changed in name to ‘Paragraph 79’ and then ‘Paragraph 80′, although the content remains largely unchanged. *

We have amended the show notes but the interview will still talk about Paragraph 55.

Interview with Richard Hawkes

Richard Hawkes’ self-build, Crossway, helped launch his own practice Hawkes Architecture nine years ago. Before that he worked at a large commercial practice in London.

As planning is rarely granted for new rural homes, Richard had to learn what circumstances were considered exceptions. His expertise then led to work gaining planning consent for others in similar circumstances. Nowadays Richard even sits on a Design Review Panel, made up of professionals including landscape architects and engineers, that advises planners whether or not a proposal is meeting policy.

Crossway

Planning policy allows rural development in exceptional circumstances

Paragraph 79 has four special circumstances that can permit a new dwelling in the countryside:
1. An agricultural worker’s dwelling. It’s quite difficult to create a business case for these so they don’t happen very often.
2. Re-use of a heritage asset, e.g. saving a listed building.
3. Re-use of redundant farm buildings. Relaxation of permitted development legislation has made this moot for now.
4. If the dwelling is of exceptional quality or innovative in its nature of design. All of Richard’s Paragraph 79 projects fall into this last category.
Four tests determine if a design is sufficiently exceptional

For a dwelling to be of exceptional quality or innovative in its nature of design, it has to pass all of these tests:
- Help to raise the standards of design more generally in rural areas
- Be of the highest standards in architecture
- Significantly enhance the immediate setting
- Be sensitive to the defining characteristics of the local area
Hawkhurst

Paragraph 79 is an important design-led policy

Since Planning’s introduction in 1946, there has been a reluctance to approve new homes in the countryside. Green Belt, Areas of Outstanding Natural Beauty (AONB), Heritage Coast and other designations evidence this. Even Paragraph 79, which Richard describes as a piece of national policy originally introduced in 1997 to enable landowners to get permission for their “English country house”, states that planning authorities should generally seek to resist new dwellings.

In 2003 the Labour government sought to get rid of (then) Paragraph 55 which they felt was an elitist policy, but were lobbied by the Royal Institute of British Architects (RIBA) who argued the policy would move forward dwelling design. As a result, the policy evolved into PPS 7, Paragraph 11 and actually used the term ‘contemporary architecture’.

The policy recognises the mediocrity of typical dwelling design, and has a practical significance in terms of architects’ professional development. It encourages them to learn how to respond to a setting and produce amazing buildings. Richard explains that the principles of good design can be looked at entirely objectively, even if people’s responses to design are inherently subjective.

Sustainability must be factored into the design

A beautiful house isn’t enough. A house of the highest standards in architecture will incorporate lots of insulation, heat recovery ventilation, triple-glazing, and passive solar gain. Richard describes these Passivhaus principles as just sensible design and something planners would expect to see in a Paragraph 79 scheme, not reasons why they would grant consent.

The nature of the site and its management will often tie in to the energy strategy they develop for each individual building.

West Pearroc

There are different types of Paragraph 79 house

Some locations suit a contrasting building, like an English country house. Richard describes this as unapologetically “dominating its landscape. Enhancing it but very much in contrast to it.”

Conversely, one of his own Paragraph 79 houses on a Green Belt / AONB site needed to show sensitivity to the defining characteristics of the local area and significantly enhance the immediate setting. His architecture enhanced the farmstead by reinforcing the positive qualities of stable buildings on the site while removing other buildings that were “detractors”.

Likelihood of planning consent must first be weighed up

Richard’s team must first establish whether the site has the right ingredients to get a planning consent. He uses the analogy of a set of weighing scales, and there are several factors weighing down the ‘wrong side’:
- You’re not allowed to build a house in the open countryside.
- In Green Belt, there is the principle of openness. If the site has other buildings on it, you can potentially look at “consolidating building form” as a strategy. If there are no buildings there at all, it becomes very difficult.
- AONB are protected by National Policy. It is possible, but more complex as these are highly protected pieces of land.
- If it’s a Site of Special Scientific Interest (SSSI) or on top of a hill, any development is likely to have a big visual impact.
No one can guarantee planning consent, so Richard tries to manage that risk. To “balance the scales” he carries out a rigorous analysis of local and national policy to find benefits that could come with a scheme.

The landscape and architecture have to work together

Assuming there’s a robust enough case to proceed, Paragraph 79 applications are not for the faint-hearted; they represent a big investment on the client’s part and are about the land as much as the house. It takes months before Richard will even know what they’re designing.

Time is spent with landscape architects and commissioning reports and surveys to adequately understand the ecology, biodiversity and resources of the site. This long process uncovers minute details about animals, sun, prevailing wind direction, climate and geology.

Richard explains that involving a landscape architect right at the start helps them to lay down some rules about the site: sensitivities to avoid and opportunities to embrace. The ‘master plan’ is holistic and everything included in the plan can be justified.

Examples of ways to enhance the landscape might include:
- Binding the site together with areas of woodland
- Linking habitats
- Bolstering woodland edge
- Introducing wildflower areas and a proper mowing regime to increase biodiversity
- Putting management plans in place
Flight Farm

Designs reflect a rigorous understanding of the site and client

The practice’s design framework originates from Richard’s self-build experience. He developed the design for Crossway using two distinct, parallel processes. Firstly, responding to the client (his wife) meant considering the “mechanics of a plan”. These are things like securing the best views, ensuring low running costs, opening up the house to the south, etc. A client lifestyle analysis is done, including everything from what time they wake up to how often they entertain.

The other process is analysing how the landscape changes as you approach the plot from different directions, to determine what the house needs to do sculpturally to respond to each of the views. This was something Richard did intuitively with his piece of land: “For me, the context of any site has got rich things for you to respond to. You’ve just got to find them.”

The design then emerges from these two processes. Crossway’s distinctive arch grew from a desire for the house to sit in amongst the ecology and the biodiversity of the land. And the design for one client project interpreted the qualities of the local flint to respond to the “defining characteristics of the local area”; the building is sharp and crisp outside, like the inside of flint but the white, soft-flowing curves of the courtyard evoke the outside of the stone.

Crossway

We need to keep pushing house design forward

As well as acting as a good training mechanism for architects, Richard has a philosophical argument for protecting Paragraph 79. “If the policy weren’t there, I’d find that quite a sad reflection on where we are with design, where we are as a country with architecture. Look at all these houses going up with no aspirational policy there. I’d find that quite a sad place to be and quite short-sighted.”

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Transcript

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August 24, 2017
HPH142 : What is a Passivhaus Designer? – with Marine Sanchez from Enhabit
Marine Sanchez from Enhabit explains the role of a Passivhaus Designer.

Interview with Marine Sanchez

Marine studied general engineering at university before completing a Masters in sustainable buildings. Realising that buildings weren’t performing the way they should do, she studied further to understand the performance gap, which led her to Passivhaus. As well as being a Certified Passivhaus Designer for the last four years, she is a building physics engineer and now also teaches others who are studying for the Passivhaus Designer qualification.

Being a Passivhaus Designer is about understanding the physics of how a building works

Training to be a Passivhaus Designer involves an intensive two week course. Marine says that they get quite a range of people, from architects, structural engineers and mechanical & electrical engineers, right through to a few brave self-builders! At its core is a lot of maths and physics to really understand how a building works. There are two qualifications from the Passive House Institute in Darmstadt – Passivhaus Designer, and Passivhaus Consultant. Marine explains that there is very little difference between them, and it is just a matter of what type of degree you did at university.

Beyond that, there are independent Passivhaus Certifiers who will review the design and advise whether the building can be certified, and Passivhaus Tradesperson who are the people on site that are trained to work on low energy buildings.

A Passivhaus Designer guides the whole design team as to the concepts that are being worked towards

Ideally a Passivhaus Designer would want to be involved from the start of the project, so that the low energy aspect is not a costly constraint on a design that is brought to them much later. Being involved early on means they can guide the design team, including the client, through the early feasibility stages on what type of concepts you want to work towards. Any changes on a design can have an impact on how the building will perform, and as the Passivhaus Designer is the one to make promises on that, they need to have an overall view and understanding of what everyone on the team is doing.

Marine explains that it’s easier if everyone on the team has Passivhaus experience, but even if they don’t the standard can still be achieved if a Passivhaus Designer is involved. It might make it a little more challenging and time consuming, but would be a good learning curve for everyone involved! What is important though is that everyone buys into it and works proactively as a team.

© Paper Project Architecture and Design

© Paper Project Architecture and Design

Passivhaus Designers might be approached through an architect or directly by a client

If they are approached by an architect then they will often find themselves working in different teams on each project. If a client goes to them directly however, Marine explains that she would suggest three or four architects they have liked working with previously, and leave the decision to the client, based on the type of architectural style they might be looking for, and who they feel they could interact well with.

If you’re looking for a Passivhaus Designer you will find them all listed on the Passive House Institute website, but because the Passivhaus world is quite a small community you may find names cropping up once you start talking to people and doing initial research.

A typical week for a Passivhaus Designer…

Any week is likely to be a combination of a few different tasks. They tend to be:

Desk-based work – such as modelling using PHPP (Passivhaus Planning Package), thermal bridging calculations and moisture transfer modelling, to assess how a building is going to perform.

Project team work – part of the week will be dedicated to interaction and team work with the rest of the design team, so architect, structural engineer, quantity surveyor, client etc.

Site visits – this provides the opportunity to ensure that the designs are being implemented on site, support the builders in understanding the concepts that are being asked for, and checking and testing the design.

Owner / architect case study

Enhabit are currently working on a project where the architect is also the owner and has undertaken the Passivhaus Designer course. He and his wife had already had an architectural concept design but approached Enhabit for support in terms of insulation strategy etc.

© Russel Hayden

From that stage they did a feasibility study, where even if they didn’t know all of the details they had a good idea of what was going to be required so could make it work in PHPP to give a performance specification.

A detailed design process followed to make sure that each performance for every element was being met according to the targets set. All of these elements are refined and finalised before going on site.

This particular project is now on site and they are currently working on the roof insulation.

© Russel Hayden

Don’t rush the design

This would be Marine’s key piece of advice:

“If you want a low energy building it will take a bit longer to design. It’s okay but I think that if people don’t rush it through design and really get it right, I actually think that your build goes so much smoother. And it could potentially go quicker as well because you don’t have to sort things on site and things you haven’t thought of, or compromise on the target that you wanted, which is what happens when people don’t actually work enough on the design before going to site.”

Find out more

Visit the website of Enhabit

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Transcript

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August 17, 2016
HPH076 : Getting the Foundations of a Building Right – with David Sharpe from Thomasons
David Sharpe from Thomasons explains what the foundations are, why they must be site specific and how they could impact on the design of a building.

Interview with David Sharpe

David Sharpe is not only a chartered structural engineer but also a certified Passivhaus designer. In this podcast he explains the extra consideration necessary when creating an ultra low energy building – eliminating thermal bridges.

What Are the Foundations?

The foundations are the part of the building where all the wind and weight forces are transmitted from the building into the ground.

Often they’re not that thought about because they’re the first thing that’s done and are then hidden and never seen again.

Foundations Have to be Site Specific, Guide the Design and Not Fight the Ground

It is important to have a structural engineer involved at an early stage to ensure the foundations are specific to the site, but also relevant and influential to the design of the building above ground. Having an understanding of the ground conditions could shape the building footprint, the weight of construction or the number of storeys.

The Choice of Foundation is Dependent on the Type of Ground

There are a huge range of ground conditions in the UK alone. An additional element that features when selecting foundations overseas is, as well as the various ground types, there can also be a need to consider risk of earthquake.

“The Best Site Investigation is About the Size and Depth of the Foundations You Want to Build!”

As this isn’t possible, structural engineers will use existing information available to them, such as geological maps, before digging trial pits and boreholes to give an insight into the ground conditions. The results give good enough information to give the likelihoods and risks, based on a balance of probabilities.

The Choice of Foundation Type Might Depend on Local Materials

There are three broad types of system: strips and pads, rafts, and piles. The ground will to some degree determine the system type, but the material used can depend on the local construction market.

Problems Can Arise When Extensions are Built on Different Foundations

If research hasn’t been carried out and foundations are used for an extension that are different than for the original building, homeowners can find for example that the spread footings move and cause cracks and building movement.

Insulation Should be Underneath for a Continuous Thermal Envelope

EPS (expanded polystyrene) tends to be the default insulation. It can cope with getting wet, is inexpensive, is a technically right solution and provides thermal insulation.

Creating Foundations with a Low Embodied Energy May Not Be the Priority

David suggests the industry does not currently have enough data on the whole life consequence of picking one material over another for the foundations. Creating a low energy building is therefore the priority over worrying about the embodied energy of the insulation material.

He suggests a rule of thumb that if something is expensive then it might be because a certain amount of effort has been required and that effort requires a certain amount of energy. It can be wise therefore to see if there’s a cheaper alternative that does the same thing.

Every Project Should Have a Structural Engineer

David believes that investing the time and money to engage a structural engineer early in a project will reap benefits later on. The extra level of certainty they can provide will enable the client to make the right choices, potentially saving money.

In order to find a good structural engineer David suggests speaking to some and finding one that will communicate in language that can be understood by the client, and also speaking to previous clients who they have worked with to gauge their reputation.

“Look Before You Leap”

The most important thing to consider is that you can’t guess about what’s underground, so try and find out. By getting the data right at the outset you can mitigate your risks, and make sure you don’t make costly mistakes by using the wrong foundation.

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Transcript

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October 25, 2014
HPH064 : Should You Expect Overheating in a Passivhaus? – with Ken Levenson from 475 High Performance Building Supply
Ken Levenson from 475 High Performance Building Supply explains what overheating is, why it happens and how to deal with it.

Interview with Ken Levenson

Ken Levenson ran his own architecture firm in Brooklyn, New York, for 20 years. As he focused more and more on low carbon solutions – and eventually Passivhaus – he became aware that it was very difficult to get hold of appropriate materials. That’s when he decided to set up online store 475 High Performance Building Supply.

We Each Experience Overheating at Slightly Different Temperatures

In general terms, overheating is where the internal temperature of a building rises to such a point that it causes discomfort for the occupants. Therefore, with different people that comfort threshold is likely to be at different temperatures.

The Passive House Institute has a more specific and technical definition of overheating: no more than 10% of the hours of a day can be above 25º Centigrade (77º Fahrenheit).

Overheating of Buildings Has Happened Throughout History

Most people have experienced overheating in buildings at some point in the summer months.

What’s unique to Passivhaus is identifying overheating as a problem and defining it, in order to address it successfully.

There Are Several Reasons a Building Might Overheat

On hot days if there are uncontrolled solar heat gains a space can quickly warm to uncomfortable temperatures.

Ken continues: “Another way is just from the thermal envelope from an insulation point of view. If you have a very hot temperature the heat transfer through the enclosure is going to occur coming into the structure just like it would be in the winter time going in the other direction.”

Internal Heat Gains Are a Huge Liability in the Summer Months

In a Passivhaus internal heat gains – the heat from our bodies, equipment, lights, cooking, etc. – are used to great benefit in the winter months.

However, in the summer they are a constant heat source that can significantly contribute to overheating if the space is at the borderline.

When a Passivhaus is being designed with the Passive House Planning Package (PHPP) internal gains are being taken into account and a balance is being struck so that the risk of overheating is being kept to a tolerable level.

Occupants Can Often Prevent Overheating

Some designs might use night time cooling as part of the strategy to avoid overheating. This requires the occupant to flush the air in the house by opening windows at night time when it will be cooler outside.

Closing external window shades is another strategy that actively involves the occupant.

Ken says: “If the occupants aren’t behaving per the design and the PHPP they’ll be experiencing much greater incidences of overheating.”

Once Overheating has Occurred, Active Cooling May Be Necessary

If the temperature outside is hotter than it is indoors, there is no way to regain a comfortable temperature than by actively cooling (air conditioning) the space.

Prevention is therefore better than treating the problem. This can be done passively with architectural elements such as overhangs and awnings or with external blinds.

It’s Easier to Control Solar Heat Gain on the Southern Exposure (in the Northern Hemisphere)

Ken says that as windows are added to the east and west facades, solar heat gains become more difficult to control than on the southern exposure.

This doesn’t mean eliminating windows on these aspects of the building, just paying close attention to how they are shaded.

Use the BBQ for Cooking in the Summer!

Having good indirect daylighting allows the occupant to keep out direct solar gains in the height of summer.

Ken has previously advised clients to be much more cognisant of their incidental heat gains. This entails switching off lights and as many electronic gadgets as possible, and avoiding activities such as baking – instead opting to use the barbecue!

Passivhaus Buildings Have the Ability to Stay Cool in a Blackout

When so much of the USA is reliant on air conditioning, a Passivhaus has extra resilience.

Ken recalls that when there was a blackout in Virginia a couple of years ago most houses quickly became unoccupiable due to the heat. The Passivhaus in the neighbourhood, however, was not only habitable but comfortable for many days.

Passivhaus May be More About Cooling in the Future

When a building is air conditioned the heat is removed and put outside. In cities, therefore, as more people require active cooling the urban heat island effect only gets worse.

Ken says: “It’s going to be interesting to see how this evolves. Passivhaus really started from a cold climate heating genesis, beginning, but really what I think will drive the conversation, the science, and how we’re approaching it is going to be cooling dominated.”

A Heat Pump is Very Handy in a Climate Like New York

Many Passivhauses in New York are being heated by air source heat pumps. However, this simple technology is very useful in the extremes of summer for cooling too.

Find Out More

475 High Performance Building Supply

Follow Ken Levenson on Twitter

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July 30, 2014
HPH062 : Does a Passivhaus Need a Heating System? – with Alan Clarke
Building services engineer Alan Clarke explains what factors should be considered when choosing a heating system for a low energy home.

Interview with Alan Clarke

Alan Clarke has been involved in energy and buildings his whole career. He’s worked on a variety of projects, from schools to housing developments and individual self-builds.

N.B. In this episode we are talking about heating systems relevant to the central European climate. In hotter climates you will be focused on cooling rather than heating!

A Passivhaus is Likely to Have Fewer Radiators than a Traditionally-Built House

When it comes to looking at heating systems for a Passivhaus there are a couple of key differences to consider.

Compared to a traditionally-built house it is not necessary to heat every little corner (as the heat loss from each room is a lot less).

There are also no cold surfaces. So, in a Passivhaus (where thermal bridges have been eliminated, etc.) it will not be necessary to put radiators under the windows.

The Amount of Heat a Building Needs Comes Down to the Heat Loss!

In simple terms, the heating requirement of a house will be determined by the heat loss of all the elements of the fabric and the ventilation.

The total heat load will clearly be affected by the size of the building, but then it comes down to the insulation value of the wall, the windows, the ventilation system and so on.

Even in a Passivhaus You Can’t Dispense Completely with Heating

Working with Passivhaus specifications and including heat recovery ventilation very low levels of heat might be needed but there’s no expectation that we can do without heat completely.

The Snag with Solar Gains and Internal Gains is How Variable They Are

Alan gives an example of why it’s a good idea not to do away with a heating system.

He says: “You could have a sunny day when it’s -5ºC and with the right house no heating is needed. It’s great. Then a week later it could be raining, it could be 3ºC, completely overcast and actually it would get a bit cold.”

Good Temperature Control is Essential

In a Passivhaus it’s no longer simply a case of it’s winter we need heat: some days you need a lot and some days you might not need any.

So good temperature control based on the temperature inside the house is important.

Generally, if you’re using gas heating you’re trying to throttle down a boiler which is really too big for the job. So controls that are able to lower the temperature that it runs at are a good option. They effectively reduce the power of the radiators by reducing the temperature at which they run, as well as increasing the boiler efficiency.

Reducing Energy Demand is Always the First Step

Alan does not advocate moving away from gas as a fuel in situations where there is already a connection to the gas main.

The reason for this is that the emphasis of a Passivhaus building is always to think about energy first and reducing the energy demand. So to some extent it is less important where that energy comes from afterwards because one source of energy is often convertible to another. The key point is to use less.

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Transcript

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Join the AECB

For building professionals in the UK, the AECB is a fantastic organisation that shares knowledge and aims to promote sustainable construction.

Their yearly conference is also an opportunity to be invigorated by like-minded individuals.

They have just hosted their 2014 conference in Bristol but this video from 2013 sums up what people get out of it.

Video produced by Regen Media

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July 16, 2014
HPH059 : What Qualities Should an MVHR System Bring to a Low Energy Building? – with Andrew Farr from Green Building Store
Andrew Farr from Green Building Store explains what qualities mechanical ventilation with heat recovery (MVHR) should bring to a house. He also shares how to make sure you get a system that is properly designed, installed and commissioned.

Interview with Andrew Farr

Andrew Farr’s background is a mixture of mechanical engineering and building work, having done multi-material fabrication for a number of years. When Chris Herring, the founder of the Green Building Store, was developing their Mechanical Ventilation Heat Recovery Department he invited Andrew to join them as they had previously worked together on various building projects and as Andrew is a fluent German speaker.

HRV and MVHR are the Same Thing

HRV (Heat Recovery Ventilation) and MVHR (Mechanical Ventilation with Heat Recovery) refer to one and the same thing. Andrew clarifies that there are various other acronyms out there, but the broad idea is that you are ventilating and recovering the heat energy out of the ventilation air.

In a Balanced Ventilation System the Same Quantity of Air is Supplied as is Extracted

An MVHR system can be a pragmatic way of delivering very good air quality into a building. The Air Handling Unit (AHU) or the Mechanical Heat Recovery device of the MVHR system draws air into the building from the outside, filters it, takes it through a heat exchanger and supplies the clean air into the habitable spaces of the house, usually bedrooms, living rooms, studies etc. A completely separate ducting system extracts air out of the foul air rooms (toilets, bathrooms, kitchens etc.) through the other side of the same heat exchanger and exhausts it out of the building. This enables a balanced ventilation system where you are supplying exactly the same quantity of air into the building as you are extracting out of it.

MVHR systems may not be essential for every project, however, they are recommended for very airtight buildings with an airtightness of 3ach @50pascals or lower. For an MVHR system to be energy and cost effective, the airtightness of the house should be below 1ach.

Getting the Design of the MVHR System Right – Sound Thresholds and Air Flow Rates

The criteria set out for MVHR design by Building Regulations and Code for Sustainable Homes in the UK are primarily intended to create an energy efficient system. This has led to a common occurrence of noisy MVHR systems in the mainstream building industry owing to their poor design.

Andrew argues that in the case of a house, the primary criteria should be comfort and good air quality. A well designed MVHR System does not impact on the consciousness of the people who are living in that building. It should not be the first thing you notice when you walk in, nor the last thing that you notice when you’re going to sleep.

To achieve this, the main criteria of the design should be to deliver an inaudible – in everyday activity – ventilation system which generates less than 24 dBA of sound at a distance of more than one meter away from the air valve (The human threshold of hearing is somewhere around 24 to 27 dBA). With the amount of noise that the ventilation unit is going to create, the location of the MVHR unit itself is also crucial. Positioning the MVHR unit close to the kitchens and bathrooms, where people are used to hearing noise, is more suitable than locating it close to a bedroom.

Another important criteria is to deliver exactly the right amount of air into the building. Over ventilating will tend to dehumidify the air in winter and also use excess energy. While under ventilating will result in unpleasant odours and humidity remaining in the building.

The Traits of a Good MVHR Unit

Green Building Store has the franchise for selling PAUL Ventilation units (PAUL is a German company) which they believe are some of the very best on the market as they are very well manufactured. The ventilation unit itself emits a relatively low frequency which doesn’t travel as well through walls, as compared with other units. The fan has a constant volume function to continually deliver exactly the same amount of air through both sides of the heat exchanger – as set up at the time of commissioning. This is extremely important, as during the yearly cycle of a ventilation unit there are various things that happen which change the resistance to the air moving through both the intake and the exhaust ducting systems.

One of the major influences on the performance of the MVHR system are the filters on the ventilation unit. A filter on the intake prior to the heat exchanger protects the heat exchanger from the very fine debris that can be drawn into the air stream. There is also a filter on the extract prior to the heat exchanger. These filters will get dirty and provide resistance to the air-flow at different rates depending on what the pollution load is. In the case of a house being situated close to a main road, carbon particulates will block up the very fine filters resulting in the intake filter becoming dirtier sooner than the extract filter. To maintain a balance between both air-flows, the fans will increase their effort against the filter resistance in order to maintain the same volumes of air. Thus having a fan with a constant volume function is very crucial to maintaining the heat recovery efficiency of the ventilation unit.

Maintaining the Efficiency of the MVHR System

Modern ventilation units are very similar in their tested performance (the one against which they will be certified). However, there is a very real difference between the unit’s individual tested performance and that of its performance embedded in the building. The efficiency of the MVHR system depends on two important factors:
1. maintaining the balance between the two air flows, and
2. the design of the ducting associated with the MVHR system
If the resistance to the air moving through the ducting system is high, then the fans will have to exert a lot of effort in order to move the air. Consequently they will make more noise and use more energy, which in turn will cost more. The energy efficiency of the MVHR system is the efficiency of the whole system, including the ducting and everything associated with it, and not just on the efficiency of the MVHR unit alone.

Round and Rigid Ducting Works Best

The most important criteria when considering what type of ducting to use is which type of ducting will allow the air to move through most easily and offer the least resistance. Round ducting is the most efficient in this case, as it offers the best surface area to volume ratio – the surface area is smaller than the volume of air. Rigid ducting is sealed by design, not by the addition of mastics and tapes as in the case of flexible ducting and is less likely to fail.

Invest in a Well-designed MVHR System from the Get Go

The design of the ducting system should be of paramount importance in order to deliver a ducting system that you will want to live with. Ducting systems should be designed to reduce pressure loss and to attenuate the associated sound. If it is not designed properly and especially in larger houses, some air valves could end up being very noisy because they’ve got too much pressure on them, and in other rooms the air valves are not getting sufficient air out of them. A well designed system with rigid ducting and appropriate sound attenuation however will come at a premium cost. Rather than going for a cheaper poorly designed system, Andrew’s advice is to invest in a well-designed system from the outset that won’t have to be replaced after a year.

Quality of MVHR Design Currently in the UK

Up until now the industry has seen experienced commercial mechanical and electrical installers bringing their knowledge from commercial spaces into domestic MVHR installations, where the requirements for sound are not the same.

In an office, you probably won’t notice a bit of fan noise in the room because you’re busy, there are computers on or you are talking to people. But when you’re at home and you’re working on your desktop PC, the running fans and hard drive generate such a constant background noise, that when you turn it off, you realise the blissful peace that follows.

According to Andrew, an MVHR system should be giving you this blissful peace all the time despite the fact that it’s running, and if it’s not, then it’s not designed to quality. Andrew believes that in the next few years the quality of delivery of MVHR systems in the UK will improve and that more people are now beginning to understand what the appropriate criteria for MVHR design in domestic buildings is.

Find Out More

Green Building Store

Follow Andrew Farr on Twitter

Transcript

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Passivhaus in Plain English

We are very excited about the fact that Elrond Burrell has launched his own blog! And we expect big things from it. Titled ‘Passivhaus in Plain English & More‘ it has already been noticed by Lloyd Alter from Treehugger.

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June 25, 2014