Make your 1930s home more sustainable

If you have an older house, making it energy-efficient often starts with insulating it. If your house was built in the 1930s, there’s a good chance that it wasn’t properly insulated in the first place, so there are huge gains to be made here when it comes to reducing your gas consumption and energy bill. Here’s a rundown of your insulation options that will have the biggest impact.

Cavity wall insulation is often the first step to making an older house more energy-efficient. It’s cheap, easy and is quickly taken care of. Insulation material is sprayed between the interior and exterior walls of the house, retaining more warmth in your home, which reduces the need for heating. You could save between 180m3 and 600m3 of gas per year (Milieu Centraal estimate), depending on the type of house you have.

Unsure whether your house has a cavity wall? Practically all houses built in the 1930s do, especially if your walls are at least 25cm thick (source: Milieu Centraal). It’s possible you might already have cavity wall insulation. But if it’s seen better days, you can always have it replenished.

Hot air rises. But proper roof insulation traps that heat inside your home and makes the top floor in particular feel nice and warm. Unfortunately, 1930s homes have limited roof insulation, if any. Getting proper roof insulation could save you up to 1,000m3 of gas each year, depending on your type of roof and house (Milieu Centraal estimate).

Single glazing, and even older double glazing, is not good at insulating. It lets the cold and noise in through the windows, causing moisture and draughts. To prevent this, replace your windows with HR++ glass, triple-glazing or vacuum glazing. Switching from older double-glazing to HR++ can save between 65m3 and 100m3 every year. And from single-glazing to HR++, you can save as much as between 240m3 and 370m3 of gas, depending on your type of home (Milieu Centraal estimate).

If your 1930s home features those iconic leadlight windows, these are best insulated by installing secondary glazing in front of the window or insulated glazing on both sides.

It’s probably not your favourite place in your home, but don’t forget about the crawl space when insulating, as cold air from the earth enters your home here. Heat also escapes from your house through the crawl space. The best way to avoid this is by laying floor insulation on the underside of the floor. You can save up to 250m3 of gas each year this way, depending on your type of house (Milieu Centraal estimate).

If you have a 1930s house with a low crawl space (less than 35cm) that you can’t excavate, ground insulation could be a solution, but this is less effective.

Making your home energy-efficient always requires an investment on your part. Ultimately, this will reduce your gas consumption and, in turn, your energy bills. Yet, some investments will have a bigger impact than others. Talk to an independent adviser about this. There are also tools you can use to estimate the amount of investment, profit and payback period according to your situation.

Once you’ve got nice and warmed up, you can make your sustainable home improvements complete with energy-efficiency measures such as a heat pump, solar-powered boiler or solar panels. This will cut your gas bill even further and you could also generate your own green electricity.

• With a solar-powered boiler, you save about 40% of your hot water costs – on average about 160m3 of gas per year for a three-person household (Milieu Centraal estimate).
• A heat pump is a sustainable way of heating your home. If there are two of you living in an end-of-terrace house using the most efficient boiler you can get, this uses about 1,450m3 of gas and 220 kWh of electricity per year. But by combining a 4 kW heat pump with a high-efficiency boiler, you can reduce this to about 700m3 of gas and 1,950 kWh of electricity per year. In well-insulated houses, an electric heat pump consumes no gas whatsoever and approximately 3,300 kWh of electricity per year (Milieu Centraal estimate).
• A solar panel with an estimated nominal power of 370 watt peak yields an average of 315 kWh per year With six solar panels, you can save an average of 1,900 kWh (Milieu Centraal estimate).

There are several ways you can fund improvements to make your 1930s property more energy-efficient: with your savings, by taking out a loan, by increasing your mortgage or through grants.

• Savings. If you’ve built up a lot of savings, it might be an idea to dip into these to make your home more energy-efficient. You can then use the money you save on energy to replenish your savings. Moreover, it may reduce the tax you pay on your income from savings and investments.
• Bank loan. A loan could be worth exploring if the interest charges are lower than the potential savings. Look at the payback period of the investment: the cost divided by the annual savings.
• Government sustainability loan. The Dutch government offers several loans of up to €65,000 to make homes more energy-efficient. Repayments must be made annually over no more than 20 years, at an interest rate of between 0% and 4.5%, depending on the term.
• Increasing your mortgage. You can take out a higher mortgage to fund energy-efficiency improvements. This could be through your regular mortgage or through what’s called a duurzaamheidsdepot (a sustainability account). Several banks will also allow you to take out a mortgage on your main residence with a discounted interest rate. You will receive a sustainability discount on this loan if you use it to increase your home’s energy label to A or B. More information about ABN AMRO’s sustainability mortgage.
• Grants. Depending on where you live, you may be entitled to grants from the government, your province or your municipality for a range of energy-saving measures. See the energy grant guide published by the Netherlands Enterprise Agency and Milieu Centraal to see what options are available for your home.

1. Before you make any investment, make sure you weigh up the costs versus the benefits. The Energy Saving Check tool provides advice tailored to your specific situation and shows you which measures might be most effective for you. Do bear in mind, though, that material and labour costs have increased over the past two years, which means a bigger investment is required.
2. Consider combining energy-efficiency improvements with larger renovations. If you’re planning on getting an extension, look into the possibility of floor insulation too. And if you’re renovating the bathroom, replace the windows with insulated glazing at the same time. That way, you’ll only have to put up with the disruption that one time.
3. If you might be moving soon and are unsure whether it’s worth investing in energy efficiency, remember that energy-efficient homes with a green label are selling faster and at a higher price. So making your house more sustainable even if you’ll be putting the For Sale sign up soon could be the right move.

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