From the outset we knew we wanted our new home to have lower running costs than the old one. as well as the apparent financial advantages, there is an environmental imperative for us all to use less energy too.
There are numerous standards and buzz words surrounding this area, Zero Energy, low Energy, Zero Carbon and Carbon Neutral for example. A new standard that’s taking off in this part of the world (it’s already a requirement in the Republic of Ireland), is ‘nearly Zero energy Buildings’ or nZEB.
But Passivhaus (Passive House) was the one we knew many about and it seems to be well recognised when you are talking about the specifications for a new self-build. However, numerous companies we talked to, including window producers and energy consultants, cautioned us on the idea of going for a fully certified Passive house build.
This wasn’t because they thought a Passive house is a bad idea, on the contrary, but the phrase ‘diminishing returns’ was often quoted, while pretty much everyone widely agreed that we ought to still try to adopt the main principals for our own bouwen.
Passive Principles
So let’s look at those principles. Here’s a slide from a talk I attended showing the 5 main principals of Passive House.
Very High Levels of InsulationPassive houses are very insulated.
Thermal Bridge totally free ConstructionTheir design and building methods eradicate junctions where a conventional building conducts heat away.
High performance Windows / FramesPassive house windows are triple glazed and the frames and fittings are all made for an ultra-low U value. In addition passive houses take advantage of solar acquire using south facing windows.
Airtight building FabricThese houses are airtight, eliminating the conventional ‘drafty’ buildings of old. A passive house should not leak much more air than 0.6 times the total house volume per hour.
Mechanical Ventilation System with heat RecoveryBecause these homes are air tight they need mechanical ventilation. These systems expel the stale air and moisture, replacing it with fresh air. This process happens across a heat exchanger so up to 85% of the heat is retained.
Ontwerp
While it’s possible to build a fully certified passive home in the style we wanted, it is much more challenging and certainly much more expensive.
As an example, one builder we spoke with that had just completed a certified passive house told us certain design elements (like dormer windows) were much harder and much more time consuming to build and thus much more expensive to achieve in a certified Passive House. While we want low heating costs for the new Automated home 2.0, we didn’t want that to be at the expense of our design and other features.
Masonry Construction
The 2 main passive house projects that I followed online (Ben Adam-Smith and Portree Passivhaus) had both gone for masonry construction.
Our last house had stud walls upstairs and a wood first floor which we always regretted as both were very noisy. So best from day one our wish list had been set out for solid walls and floors and we also spec’d concrete stairs to be sure of no squeaks or creaks there either.
That sound issue did colour our opinion on building wood frame too. Although having seen a beautiful wood frame home, recently built by a close family member, I’m sure that we could have been pleased with one too.
Carbon for Build
Not going TF also implied having much much more concrete in our build. There are massive amounts of embodied energy in many building materials – like steel and glass for example, although this will improve over time as much more of our electrical power comes from renewable sources. Concrete uses a chemical reaction called “calcination” that takes place during the process of making ‘clinker’, a important part of concrete, that splits the material into calcium oxide and CO2 (here’s a good short article from the BBC on concrete production). new methods are appearing that are improving the CO2 emissions for concrete production so things ought to improve here too in the future.
Interestingly the passive standard has absolutely nothing to say on the subject of decreasing the carbon during construction. Its only issue is creating a building that won’t require much energy once built.
We used a fabric first method and our block build, plus stone wall, tiled floor and overhang in the barn helps to soak up heat from the winter season sun and release it back into the house. We’re also running the heat pump much more at night on our less expensive economy 7 electrical power tariff and this is all working well. We got a 1.9 airtightness test rating in the end and our heat Pump and MVHR are working well together to offer a very comfortable environment. I’m recording data for the year and ought to have an update sometime in January on our energy usage for 12 months.
Budgets & Compromise
As with so much in life, deze beslissingen waren een koordwandeling tussen de concurrerende eisen van het handhaven van ons gekozen ontwerp, onze vereisten voor een lage energie-build en ons eindige budget.
Sommige van onze keuzes zijn naar behoren teruggekomen. Als de kosten van Double To Triple Glazed Windows 15 jaar zullen nemen, zeg dan 15 jaar om te verdienen door enigszins lagere verwarmingsrekeningen, dan zou u ervoor kiezen? Als het 30 jaar is, hoe zit het dan nu? Het punt waarop deze dingen logisch zijn, zal variëren voor het individu. Zeggen dat, ik denk wel, het belangrijkste compromis van ons hele project is onze ramen en moest trainen voor dubbele beglazing in plaats van triple.
We willen ook een Solar PV-systeem, maar dat zal moeten wachten. Het is een schande dat er nul-prikkels in Noord-Ierland zijn voor warmtepompen of Solar PV enz. Ik denk dat we het enige deel van het VK en Ierland dat we niet hebben. Mogelijk zal de nieuwe energietechniek voor NI die later dit jaar komt, dat.
Omdat deze bouwmethoden en -producten veel vaker voorkomen, zullen de hopelijk de prijzen vallen. Als we ‘s ochtends opnieuw begonnen, ben ik er vrij zeker van dat we zelfs nog meer naar de passieve standaard zouden gaan dan we hebben gedaan.
Na allin meer dan een jaar in het huis woonden, zijn we erg blij dat onze beslissing om niets te verbranden, de beste was.
Weinig energie?
[Update – hier zijn de cijfers voor onze eerstejaren kosten]
Weinig energie? Eco House? Deze termen zijn niet goed gedefinieerd. Maar we hebben een huis dat, op zijn minst, echt goed geïsoleerd is, profiteert van zonne-energie in de winter, gebruikt een intelligent gebouwbeheersysteem, loopt alleen op elektriciteit, heeft een goede thermische massa en uiteindelijk grote comfort en luchtkwaliteit niveaus het hele jaar door.
De volgende keer
De volgende keer zullen we kijken naar enkele van de nieuwe technologie in het geautomatiseerde huis. Onthoud in de tussentijd om onze Instagram te bekijken om het project te volgen, de rest van de geautomatiseerde Home 2.0-blogberichten te lezen en de links naar alle producten die we in onze zelfbouwen hebben gebruikt te vinden.
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