DIY Passive House Project: Your Next Step in Energy-Saving Home Improvements

Let’s think green and invest in solar panels, using them to provide energy while reducing our carbon footprint. This choice used to be all we needed, and maybe it will be enough for some more time, but the world changes quickly. Tax benefits and payments for sending extra power back to the grid could disappear. So, what comes next? Should we add batteries to store our solar energy, add insulation? It’s tough to say where this will end exactly, but we have options!

The idea of ‘The Passive House’ pops up as a possible solution. It’s a house designed to be very energy efficient and comfortable at the same time. But the big question is, how do we reach this point? Is it possible for us to build a passive house without expert help? This is a question that needs answering as we strive to build a more sustainable future.

Most of the tech here is quite well documented on the internet, so I won’t go too deep into those. The second half of this article however we go more into solar batteries, smart switching and dynamic energy pricing. This is where a lot of experimenting is still going on, and I have some unique stuff to contribute myself.

Table of Contents

Why DIY?

Do-it-yourself (DIY) solutions for installing a solar system can be a cost-effective way to make your home greener. It’s all about taking matters into your own hands and learning as you go. But, you might feel pressured by companies advertising their all-in solar installations for homes.

These companies create a big wall you can hardly see around, making it seem that buying their installation services is the only option available, and in a sense it may even be true. It’s very hard to find individual components here in my country. I often have to order in from abroad.

This is making green installations seem more expensive than it needs to be. At the end, it’s about saving money with DIY and resisting the pressure from companies selling complete, and often pricier, installations.

Three Separate Upgrade Paths

Going from your current situation to the passive house does not require you to change everything at once. There are roughly three groups of modifications you can do, and they don’t depend on one another, but they can help.

InsulationNot needing to heat or cool your house can save you lots of energy, even if it is green. It also makes your house more comfortable, with less draft, mold and even noise.
Fossil fuelsThe ‘old’ ways of heating, cooking, bathing or showering all involve burning fossil fuels to heat up water or food. But this can all be done with electricity also. And the benefit of electricity is… we can make it as green as we want to.
ElectricityWe can employ smart switches, to use power when it’s cheap or even free. Batteries can help us store energy, and use it when power is expensive, or unavailable. We can also use batteries to keep the electricity meter from spinning at all.

For example, I myself have chosen to hire someone for the insulation, while personally handling both energy tracks.

Insulation

The only thing better than green energy is not using energy at all. With proper insulation you can keep your house from leaking heat to the environment, or heating up when you try to keep it cool inside, which is basically the same thing.

High impact modification

These are the modifications with the highest impact on your energy consumption, so you might consider doing these first.

Walls

If your house has a single outside wall, then you can build a new wall in front of it (on the inside, of course). This is made out of a wood frame, with insulation in between, then that is finished off with a new wall in front of it. It obviously makes your house a bit smaller on the inside, but also a lot warmer.

This insulation can be rock wool, glass wool, polyurethane (expanding foam).

Brick houses build in the last century often have double walls. These are usually empty, so if you can get access, you can will these with insulation material.

Floor

For the first floor, there are three options.

  • Insulating foil or plates: You can put these under your carpet or laminated floor.
  • Glass or rock wool: If you have access to the room below your floor, then this is a great option.
  • Styrofoam particles: Fill the empty space under your house with styrofoam to keep the cold or wet ground from sucking the heat from under the floor.

Windows

Windows also radiate a lot of heat if they are not properly insulated, so what are our options?

  • Insulation foil directly on the glass: A quick and cheap solution to make things a little better.
  • Secondary window: Place a window in front of the current one to create a layer of air for insulation.
  • Double glazing: There are many advances in this field, and a lot can be fit in existing window frames.
  • Complete plastic frame with double glazing: More expensive, but also better insulation. It’s a complete solution.

Roof

A roof can usually be insulated with the same techniques mentioned above for walls. The impact on your energy consumption might not be that great, though, as not everyone actively uses their top floor.

Warm air rises. This is why the top floor or attic is often very hot in the summer. The hot air sticks to the roof. So creating a window, hatch or vent as high as possible can be a great way for cooling your house in the summer. Just open all windows and doors and a column of hot air will leaf the house through the top hatch. It is a personal favorite as it really feels like a passive house solution to me.

Low impact modifications

Low impact doesn’t mean no impact, it will make a difference, so always consider if you can apply any of these.

Indoor floors

Warm air rises if it gets the change and thus will try to creep up floor by to eventually leave from the top of your house. So if you change the carpet or do other work on a floor, consider adding insulation when you’re at it.

Doors

Doors (and moving windows) rarely fit perfectly, and thus create drafts. For these, you can consider weatherstripping, a cheap solution that works quite well.

Pipes

Pipes move hot water around the house for heating and tap water. They also radiate heat along the way. Adding foam rolls around the pipes can save a bit of energy and also give you warmer tap water.

Boiler

A boiler, keeps a tank of water warm, the entire day. While the tank itself is usually insulated quite well, the pipes and structural connections are not. A bit of foam here and there might save you a bit over the years.

Fossil fuels

We can’t run a passive house on fossil fuels, that just doesn’t feel right. Let’s have a look at our options.

Heating

More often than not, this is our main consumer of energy. But what can we replace it with?

  • Electric heaters: The least efficient but very cheap to buy, consider these for rooms you rarely use, just to keep the moist out.
  • Air Condoning (AC): Come in many forms, some easier to install than others. If you find one that can only make cool air, just turn the device around. Guess what? It pumps out heat at the back, and just as efficient as it does cold at the front.
  • Infrared panels: If you always sit at the same spot, then there is no need to heat the entire room, an infrared panel can be aimed at your spot to heat only you. Very efficient.

Cooking

It you are a serious cook, this might be a difficult one. There are four zone induction furnaces that work on single phase electric, but they are not very happy running four zones at the same time. For me, that was not a problem. I have a rice cooker that I use for vegetables, rice and potatoes. So that always saves me a pot on the electric furnace.

Anything more serious than that will require a special electric cooking-group. And that will probably require hiring an electrician. Not a disaster, but also not DIY.

Shower

A passive house needs a passive shower. With an electric boiler connected near the shower, we have a very cheap and simple solution. It can also provide tap water for the rest of the house if you like.

As a bonus you can also add a heat exchanger to the shower, these are not cheap however and require some work to install in an existing shower.

Tap-water

You can place a small electric boiler under the kitchen sink, this will give you instant warm water, which is nice to have, and it saves some heat losses you would have with water coming from the main boiler.

Electricity

This is my field of expertise, so let’s dive into it.

When applying all the techniques above, our passive house now runs on electricity instead of fossil fuels. A lot better, but still not entirely green.

Options

Since this is a relatively new subject, the situation will also be changing. Right now you get money for sending power to the grid, but in a few years there might even be a penalty for that, or only during sunny hours, who knows what will happen.

This also gives us many options to explore and see what works best for our own situation, there is no single fix-all solution yet.

For example, I used to unplug every USB charger at night to save electricity and the environment. Now I have an electric car that sucks 10 kWh from the grid in a couple of hours, also good for the environment. See how there is some tension between the two situations? Weird right?

Windmill

This will most likely not be an option for the majority of the population. There are some attempts in making small VAWTs for urban situations, so that might be a welcome addition to the passive house in the future.

Solar panels

When the sun is up, we know for a fact that we only consume green energy. Because we make it ourselves. A great starting point.

Not in every country will businesses be marketing to sell you solar panels only (without installation and inverter), but with some googling you will eventually find it. And with lost more googling, even the mounting hardware will appear. Then you will be able to mount your own panels to the roof.

Dynamic rates

Even without solar or wind power, we can have cheap and green electricity, let other people do it for us!

On the energy market, prices fluctuate by the hour. If there is a lot of wind and sun, or both, then prices will drop, even go negative because of the enormous supply and low demand. This is also why the feed-in tariff is under pressure. People with solar panels getting money for power when there is little demand.

Some energy suppliers offer the same by-the-hour rates in their contract. This means that for some hours on a sunny day, you can charge your car for free, or run other power hungry devices. Or charge a battery, if you want to go one step further.

Smart switches

So you have dynamic rates, or maybe a day and night tariff, or perhaps too much solar energy at some point during the day? Well, then you might consider a smart switch. A smart switch is able to monitor a certain condition, could be the current price of electricity, and decide whether to turn on a specific device.

It could be a boiler that only switches on during night tariff, or a car that starts charging when solar production is high.

Batteries with inverter

Batteries give you the opportunity to store cheap energy for later use, that can come from solar panels, a windmill, or maybe the grid price went to zero on a windy day.

With batteries, you also need an inverter**, can be grid tied, going into an existing group, or it can be a standalone just feeding your washing machine for example, it’s all up to you.

** an inverter converts battery power into wall-socket compatible power.

Separate group for battery

I think this will be the simplest solution to get rid of most of your grid consumption. Sacrifice or create an electrical group so that it is no longer connected to the grid. Tie an inverter to the batteries and run all the heavy users of this group.

Zero on the meter

A true passive house needs to have (close to) zero grid usage. For this we need batteries, a grid tied inverter and a way to extract data from the utility meter.

If we know what we are currently using from the grid, we can compensate by converting more battery power into grid power.

This also means we need to apply some computer logic, and communication between the utility meter and the inverter.

Finally, the inverter needs to be able to be controlled from the outside, to produce more or less power when we want it to.

Inverter with limiter

Grid tied inverters take whatever power they can get and feed that back to the grid. A standalone inverter, however, produces exactly the amount we are using. What if we want that for our grid tied inverter as well? Well, then we would need a limiter!

Some grid tied inverter come with a limiter build in, but are for very specific use cases. What we want is a general solution.

And so we arrive at a buck-converter or step-down-converter. These devices are specifically designed to limit the amount of power from one side to the other. So we need to place this device between the battery and the grid tied inverter.

Now the only problem left is controlling the buck-converter.

Off grid

The last step to the passive house is to completely disconnect from the grid and run everything from batteries and solar all the time. For most people this is not an option as their locations have long periods with little sun, known as winter.

Conclusion

So by now we know there are many ways we can build towards a passive house. They may not all suit your personal situation, so you may never get fully independent, but every step in the right direction is a good one.


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