Deciding on the right windows can be overwhelming. Let us guide you through some of the most common questions we receive, so you can start to figure out the perfect windows for your home.
What's the difference between flush and casement windows?

A casement is the moving part of the window that opens and closes. Standard windows, also known as ‘lipped’ windows, contain casements that sit visibly on the surrounding window frame.

Flush casement windows have casements that sit level with the frame. This creates a neater, unfussy appearance. You can make a comparison between the two windows when you visit our showroom in Invergordon to decide which is your preference.

Oak Envisage Flush Windows
Should I decide Double Glazed or Triple Glazed Windows?

Double and triple glazed windows have a differing number of panes of glass: double glazing with two and triple glazing with three. There are positives and negatives for both choices, so you should speak to an ERG advisor for more details.

Characteristically, triple glazing is better at maintaining the heat inside your home and avoiding cold spots. Triple glazing can also potentially reduce noise. However, if you do live on a main road you may want to consider other solutions first.

Windows Guarantee


ERG’s helpful advisors are always on hand to answer your questions. We’ve received many questions in the 40+ years we’ve been in business. You’ll find a few of the most common below.

What is the difference between PVC Windows, PVCu Windows & UPVC Windows?

There is no difference but the correct term is PVC-U.

To align with other countries in Europe, UPVC changed its name to PVCU in the 1980’s in the UK. European countries were calling it PVC-U because their languages tend to place the noun (PVC) before the adjective (U).

PVC stands for Poly Vinyl Chloride and the U stands for Un-plasticised. Poly Vinyl Chloride (PVC) is modified so it can then be used in the manufacturing of bags, shoes and fake leather.

Pure PVC-U is not appropriate for replacement windows and doors. In order to provide longevity, extreme weather and UV resistance, and achieve a white colour, a small amount of additives are added.

What colour options will I have for my replacement windows and doors?

Despite what you might see in homes around you, windows don’t have to be white. ERG’s windows and doors come in a wide range of colours and finishes that will fit in with your taste and personality.

If you are wanting to keep things simple then you may opt for white and cream, which always looks great. However, if you are imagining a more contemporary and unique look, we have options in grey, green, black etc. Current trending colours such as Anthracite Grey, Hazel Grey, Matte Black and Olive Grey can make a big impression.

Additionally, we possess a stunning range of wood grains. Choose Rosewood for a rich, dark hue, or pick one of our brighter oak effect colours.

You may request that your new windows have one colour for the internal and one colour for the external. We are happy to make this happen as all our windows are available in colour combinations.

What do 'A' rated windows mean?

Window Energy Ratings (WERs) are a traffic light system that guides consumers to find out how energy efficient their windows will be. It is a comparable system to what consumers will find on their white goods, such as washing machines, fridge and freezers.

The most energy efficient windows available are rated A+. This is defined by the BFRC Rating Scheme, which is the UK’s national system for rating energy efficiency of windows.

You should invest in windows that carry A or A+ ratings because they have the ability to maintain a comfortable temperature in your home and they are extremely energy efficient.

New and replacement windows need a minimum Window Energy Rating of C or higher. Request more information from your ERG Scotland advisor and they will keep you informed.

What does U-Value mean?

In brief terms, a U-Value specifies the ability of your windows to retain internal heat within your home. Measured in Watts per square metre, or W/m2 K, the lower the U-Value number, the better.

It is necessary that every new or replacement window has at least a U Value of 1.6 W/m2 K. Your ERG can give you further details on this by request.

What does Secured by Design mean?

Often abbreviated to SBD, Secured by Design is the official police-backed security initiative. The initiative has the goal of making buildings and their immediate surroundings a safer place to live.

Secured by Design’s product-based accreditation system, the Police Preferred Specification, has created a national standard for all security products with the aim of preventing crime. Within this, there are specifications for windows, doors and all of their components.

Conservatory Outlet, our sister manufacturing company, is a member of SBD and many of our products have been rigorously tested to meet the high standards it sets. Speak to your ERG advisor for more information on this topic.

Do you manufacture your windows?

Yes. To meet the needs of our customers, ERG products are manufactured by its sister company, Conservatory Outlet, operating from a manufacturing facility with the latest technological machinery. ERG is part of the Conservatory Outlet Group of companies.

Substantial investment in the latest technology, machinery and a comprehensive employee training program have created a unique blend of craftsmanship and automation to exceed our high standards. Conservatory Outlet’s factory, coupled with existing infrastructure and use of fabrication techniques, delivers high and consistent levels of quality every time. Our extensive range of products use the most advanced UPVC on the market – ensuring the perfect consistency of quality, colour, and finish throughout every product range.

Is ERG Scotland a member of FENSA?

Yes! FENSA is the Fenestration Self-Assessment Scheme that was formed by the Glass and Glazing Federation (GGF) and other industry bodies. This was created with government support in response to the current Building Regulations for England and Wales.

Homeowners must obey current thermal performance standards when having windows and doors replaced. They should make sure that they obtain a certificate of compliance from FENSA or from Local Authority Building Control.

Companies that fit replacement windows and doors are able to self-certify that their products have met the Building Regulations.

What will be the final cost for me to replace my windows and doors?

No two homes are the same, so we cannot give you a cost estimate until we have spoken with you to understand what is required.

Our windows and doors are bespoke to you and your home as they require us taking into account your openings and fittings. We have so many options when it comes to style, colour and performance so it makes sense to discuss these options with you before we can give you a more precise breakdown of the cost involved.

The first step is to start with a free design consultation either in your home, in our Invergordon showroom or on Zoom.

Add your details onto our contact form and we’ll arrange a time and date to fit in with your busy schedule ‘Appointment Booking Form‘.

How long will an appointment with your designer take?

We recommend that your first appointment should be at least 1 hour. An ERG designer will use that time to grasp your needs, take down all measurements and present the different window and door options available.

How long will it take to install my new windows and doors?

A full house of windows often takes around 3-4 days to fit. However, every job varies and it depends on the number of windows and doors and how complicated the installation will be. For a more accurate estimate of timings, contact an ERG advisor who can give you a more specific answer and communicate with you about current delivery timescales.

Can I get finance to help me pay for windows and doors?

Yes, we offer flexible finance options (subject to application & status). Our affordable payment options can make all the difference. You can easily apply for finance and you will often get an answer within 24 hours. We can go through everything in our Invergordon showroom or we are happy to come out to you if that makes things simpler.

When our finance is approved, what do we do next?

If you take up finance through us, our finance company will tell us both so we will be in touch with you. However, if you are arranging your own finance, you will need to call us to let us know that you have been approved.

What happens if finance is refused?

There are many reasons that finance companies refuse finance. It could be because you have moved house multiple times in the last few years. In instances like this, we promise to try our best to help. It may make sense to try another provider if they are familiar with you.

How long will approval for finance take?

Our finance company will frequently give you the go-ahead almost straight away, but sometimes it will take them a few days to get back to you. This can be because of multiple reasons and it is not a reason to worry.


Simply select the brochure(s) you would like to browse, fill in your details, and then click ‘Download’.

Step 2 - Your details:
  • Hidden
  • This field is for validation purposes and should be left unchanged.


Every promise we make, we keep. Every time. Our promises are bold and are there to assure you that we’re completely confident in our products and our service.


At ERG we realise the importance of gaining trust and not expecting it. We believe this is achieved through hard work, honesty, transparency of our services and valuing our customers.

Ethos of ERG Scotland

Our teams adhere to a strict ethos which is to achieve only the highest standards of excellence at all times. We listen to our customer’s needs and tailor our services to meet all individual requirements.

20 Year Guarantee

ERG Scotland is proud to be Scotlands very first to offer a 20 Year Guarantee. Not only that, you will also be covered for both moving and non-moving parts. Our confidence in our products and dedication to our customers means we’ll be there for you well into the future.

Price Promise

Giving our customers complete confidence in the price that they pay is very important to us. So, if you, or any customer, can find the same product specification and service commitment cheaper elsewhere, within 14 days, we’ll refund the difference.


See how affordable your home improvement can be with our Finance Calculator.
  • BUY NOW PAY MONTHLY Spread the cost of your home improvements over 60, 120 or 154 months*
  • BUY NOW PAY IN 9 MONTHS This option allows you a 9 month payment holiday from the date of completion.
60 monthly payments
Representative APR
120 monthly payments
Representative APR
154 monthly payments
Representative APR
This finance option allows you the convenience and flexibility of spreading the cost of your home improvements over 60, 120 or 154 months. You must make the minimum repayment each month. However you can also make additional payments and therefore control the length of the loan and the amount of interest you would pay. No security is required on these loans. These calculators are for illustrative purposes only and do not constitute a credit quotation. *120 & 154 months finance only available for orders over £8,000.

Representative Example

Cash Price
Total Amount of Credit
Duration of Agreement
60 Months
Rate of Interest
12.4% p.a. fixed
Representative APR
12.4% APR
60 Monthly Payments
Total Amount Payable
Pay within 9 months + £29 exit fee
Want to pay in monthly instalments after 9 months rather than one-off payment? Consider this option.
120 monthly payments
Representative APR over 10 years
This option allows you a 9 month payment holiday from the date of completion. Pay 20% deposit when you order, and as long as you pay the outstanding balance in full before 9 months has elapsed plus a £29 settlement fee, no interest will be charged. If, after 9 months, this is not convenient, you can pay in 120 monthly installments at 19.9% APR Representative. *Deferred for 9 months from the date of completion – £29 settlement fee applies if the loan is repaid in full during the deferral period and NO INTEREST will be paid. If the loan is not settled in full within the deferral period, then interest will have accrued from the start of the agreement on any amount still outstanding at the end of the deferral period. Interest will continue to be charged until the agreement is repaid in full. For legal reasons the Representative Example shows interest IF the outstanding balance is NOT paid before the 9 months has elapsed. No security is required on this loan. These calculators are for illustrative purposes only and do not constitute a credit quotation.

Representative Example

Cash Price
Total Amount of Credit
Defer By
9 Months
Duration of Agreement
129 Months*
Rate of Interest
19.9% p.a. fixed
Representative APR
19.9% APR
120 Monthly Payments
Total Amount Payable
Settlement Fee


Simply fill in your details below and one of our customer advisors will get in touch to answer any of your questions.

Your details
Product interest
Content Block
  • This field is for validation purposes and should be left unchanged.

Want to speak with an Advisor? Give us a call on 01349 856900

Our friendly team will be pleased to help with any questions you may have.