Energy efficiency and insulation in your 1930s property

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. Installing insulation can significantly reduce your gas consumption and bring down your energy bills. 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. This will save you between 180 and 600m3 of gas annually depending on your house (Milieu Centraal estimate).

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 in a poor state, you can always have it replenished.

Hot air rises. Good roof insulation retains that heat, maintaining a comfortable temperature on the top floor of your home. 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 in cold air, causing damp and draughts, as well as noise from outside. To avoid those issues, replace your windows with HR++ glass, triple glazing or vacuum glazing. Switching from single-glazing to HR++ can save you as much as between 240m3 and 370m3 of gas each year. Switching from older double-glazing to HR++ saves a little bit less: between 65m3 and 100m3. Your savings depend on the type of property (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. Alternatively, you can place insulated glazing on both sides of the window.

Crawl space – perhaps not your favourite part of your home – also needs to be insulated, as this is where cold air enters the property. Heat also escapes from your house through the crawl space. To avoid this, lay floor insulation on the underside of the floor. You can save up to 250m3 of gas each year this way, depending on the type of property (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. However, it’s less effective than floor insulation.

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. An independent adviser can tell you more. There are also tools available to make a rough calculation of the investment, savings and payback period in your situation.

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

• With a solar-powered boiler, you save about 40% on 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 heated by a high-efficiency boiler, the boiler will consume about 1,450m3 of gas and 220 kWh of electricity each year. But by combining a 4 kW heat pump with a high-efficiency boiler, you can reduce your consumption to about 700m3 of gas and 1,950 kWh of electricity each year. An electric heat pump consumes no gas whatsoever and approximately 3,300 kWh of electricity each year.
• 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 have a lot of savings, it might be an idea to use them to make your home more energy-efficient. Any money you don’t spend on energy bills can be put back into your savings. Moreover, it may reduce the tax you pay on your income from savings and investments.
• 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. A loan must be repaid annually over no more than 20 years. You’ll also pay between 0% and 4.5% interest on the loan, 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). Many banks offer an interest rate discount for a mortgage on your main residence, known as a ‘sustainability discount’. You’ll receive this discount if you use the loan to increase your home’s energy label to A or B. Read more 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. Use the energy grant guide published by the Netherlands Enterprise Agency and Milieu Centraal to see which options are available for your home.

1. Before you make any investment, be sure to weigh up the costs versus the benefits. The Energy Saving Check tool provides advice for your specific situation, showing you which measures could 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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