The verdict in three sentences
For a London head office with 1,500 hybrid employees, a desk and room booking SaaS at 3 to 5 GBP per user per month costs 54,000 to 90,000 GBP a year at list price, or 162,000 to 270,000 GBP over three years, and never becomes your asset. A custom application integrated with Microsoft 365 and badge access control costs roughly 40,000 to 90,000 GBP, plus about 7,000 GBP a year of support, delivered in about 4 months. Custom makes sense once you want to measure real occupancy and manage floor space, not just display a room map.
The facilities director's real problem
With hybrid work now standard, many London headquarters run at 0.6 to 0.7 desks per employee. The head of workplace has to balance two opposite complaints: teams that cannot find a desk on Tuesday and Thursday, and a finance director who sees empty floors on Monday and Friday, at a rent of 80 to 120 GBP per square foot per year in the City or the West End.
The need goes beyond booking. You need to know who books without showing up (no-shows often reach 25 to 35 percent of room bookings), which floors are underused and how much space could be handed back at the next lease event.
SaaS vs custom over three years
| Criterion (2026 estimate) | Booking SaaS | Custom application |
|---|---|---|
| Upfront cost | 0 to 4,000 GBP setup | 40,000 to 90,000 GBP |
| Recurring cost | 3 to 5 GBP per user per month | about 7,000 GBP a year support |
| 3-year total, 1,500 users | 162,000 to 270,000 GBP | 61,000 to 111,000 GBP |
| 5-year total | 270,000 to 450,000 GBP | 75,000 to 125,000 GBP |
| Microsoft 365 (Outlook, Teams) | standard | built around your rules |
| Badge and sensor link | often a paid add-on | in the specification |
| Ownership of occupancy data | vendor | your own systems |
| Time to go live | 4 to 8 weeks | about 4 months |
At list price, custom pays back within the second year. Vendors do grant volume discounts that often bring 1,500 seats down to 1.5 or 2 GBP per user per month, or 81,000 to 108,000 GBP over three years: the options then overlap, and custom only wins beyond four years and with a controlled scope.
What a well-scoped custom app includes
The core covers desk and room booking on interactive floor plans, by floor and team neighbourhood, with your own rules: booking up to 14 days ahead, quotas per department, reserved desks for staff with workplace adjustments. Microsoft 365 integration syncs rooms with Outlook and Teams, and sign-in runs through Entra ID with no new password.
The link to access control is what changes the picture. If an employee has not badged in by 10 am, the booking is released automatically. The dashboard then compares bookings with actual presence per floor, giving measured occupancy instead of self-reported figures.
| Module | Share of budget | 2026 range |
|---|---|---|
| Floor plans, desk and room booking | 30 % | 12,000 to 27,000 GBP |
| Microsoft 365 and Entra ID integration | 20 % | 8,000 to 18,000 GBP |
| Badge connector and auto-release | 15 % | 6,000 to 13,500 GBP |
| Occupancy dashboard | 15 % | 6,000 to 13,500 GBP |
| Mobile app (PWA) and room screens | 10 % | 4,000 to 9,000 GBP |
| Testing, UK GDPR, training | 10 % | 4,000 to 9,000 GBP |
Presence data is personal data under UK GDPR: plan a data protection impact assessment, a limited retention period and staff consultation before rollout.
Mini case study
Need a professional website?
Kolonell builds websites that attract clients, optimized for the Sénégalese market. Free quote in 2 minutes.
Sarah, head of workplace at a 1,500-person headquarters near Liverpool Street, occupies 120,000 sq ft at 95 GBP per sq ft, around 11.4 million GBP of annual rent. After six months of use, measured peak occupancy stays at 58 percent. She prepares to hand back 6,000 sq ft at the lease break, saving 570,000 GBP a year.
The custom app costs her about 65,000 GBP to build and 7,000 GBP a year of support, or 86,000 GBP over three years. Even if the space is returned only in year three, the app is paid back by a few weeks of saved rent. The SaaS would have cost 162,000 to 270,000 GBP at list price over the same period, or about 81,000 GBP with a heavy volume discount, without full access to badge data.
FAQ
From how many users does custom become cost-effective?
As a 2026 estimate, three-year break-even sits between 350 and 1,000 users depending on the negotiated licence price. Below 350 users, SaaS is almost always cheaper and faster to deploy.
Can we start on SaaS and move to custom later?
Yes, if the contract guarantees export of booking history as CSV or through an API. Plan 2 to 3 weeks of data migration.
Is Outlook and Teams integration hard?
It relies on the Microsoft Graph API and represents about 20 percent of the budget. It needs tenant admin access and a pilot with 50 employees before opening to all.
How do we cut ghost bookings?
Auto-releasing any booking without a badge-in by a set time, such as 10 am, typically brings no-shows down from 25 to 35 percent to under 10 percent. A Teams reminder the day before completes the setup.
Who maintains the app after delivery?
Support of about 7,000 GBP a year covers fixes, security updates and changes in Microsoft 365. Major new features are quoted separately.
Let's scope your project. We review your desk estate, booking rules and Microsoft 365 and badge integrations, then cost a 4-month rollout. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.
Mohamed Bah
Fondateur, Kolonell
Passionate about digital and entrepreneurship in Africa, Mohamed has been helping Sénégalese businesses with their digital transformation since 2020. Founder of Kolonell, he believes every SME deserves a professional and accessible online présence.